Abstract

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OBJECTIVES:

The aim of this study was to test whether adenosine triphosphate-sensitive K⁺ (KATP) channel expression relates to mechanical and hypoxic stress within the left human heart.

BACKGROUND:

The KATP channels play a vital role in preserving the metabolic integrity of the stressed heart. However, the mechanisms that govern the expression of their subunits (e.g., potassium inward rectifier [Kir] 6.2) in adult pathologies are mostly unknown.

METHODS:

We collected biopsies from the 4 cardiac chambers and 50 clinical parameters from 30 surgical patients with severe mitral dysfunction. Proteins and messenger ribonucleic acids (mRNAs) of KATP pore subunits and mRNAs of their known transcriptional regulators (forkhead box [FOX] F2, FOXO1, FOXO3, and hypoxia inducible factor [HIF]-1α) were measured respectively by Western blotting, immunohistochemistry, and quantitative real-time polymerase chain reaction, and submitted to statistical analysis.

RESULTS:

In all heart chambers, Kir6.2 mRNA correlated with HIF-1α mRNA. Neither Kir6.1 nor Kir6.2 proteins positively correlated with their respective mRNAs. The HIF-1α mRNA related in the left ventricle to aortic pressure, in the left atrium to left atrial pressure, and in all heart chambers to a decreased Kir6.2 protein/mRNA ratio. Interestingly, in the left heart, Kir6.2 protein and its immunohistochemical detection in myocytes were maximal at low venous PO(2). In the left ventricle, the Kir6.2 protein/mRNA ratio was also significantly higher at low venous PO(2), suggesting that tissue hypoxia might stabilize the Kir6.2 protein.

CONCLUSIONS:

Results suggest that post-transcriptional events determine Kir6.2 protein expression in the left ventricle of patients with severe mitral dysfunction and low venous PO(2). Mechanical stress mainly affects transcription of HIF-1α and Kir6.2. This study implies that new therapies could aim at the proteasome for stabilizing the left ventricular Kir6.2 protein.

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Abstract

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OBJECTIVE:

Patients with coronary artery disease complicated by moderate ischemic mitral regurgitation have demonstrably poorer outcome than do patients with coronary artery disease but without mitral regurgitation. The optimal treatment of this condition has become increasingly controversial, and a randomized trial evaluating current practices is warranted.

METHODS:

We describe the design and initial execution of the Cardiothoracic Surgical Trials Network Surgical Interventions for Moderate Ischemic Mitral Regurgitation Trial.

RESULTS:

This is an ongoing prospective, multicenter, randomized, controlled clinical trial designed to test the safety and efficacy of mitral repair in addition to coronary artery bypass grafting in the treatment of moderate ischemic mitral regurgitation.

CONCLUSIONS:

The results of the Cardiothoracic Surgical Trials Network Surgical Interventions for Moderate Ischemic Mitral Regurgitation Trial will provide long-awaited information on controversial therapies for this morbid disease process.

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Abstract

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Acute and 12-month results with catheter-based mitral valve leaflet repair: the EVEREST II (Endovascular Valve Edge-to-Edge Repair) High Risk Study.

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Abstract

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OBJECTIVES:

The EVEREST II (Endovascular Valve Edge-to-Edge Repair) High Risk Study (HRS) assessed the safety and effectiveness of the MitraClip device (Abbott Vascular, Santa Clara, California) in patients with significant mitral regurgitation (MR) at high risk of surgical mortality rate.

BACKGROUND:

Patients with severe MR (3 to 4+) at high risk of surgery may benefit from percutaneous mitral leaflet repair, a potentially safer approach to reduce MR.

METHODS:

Patients with severe symptomatic MR and an estimated surgical mortality rate of ≥12% were enrolled. A comparator group of patients screened concurrently but not enrolled were identified retrospectively and consented to compare survival in patients treated by standard care.

RESULTS:

Seventy-eight patients underwent the MitraClip procedure. Their mean age was 77 years, >50% had previous cardiac surgery, and 46 had functional MR and 32 degenerative MR. MitraClip devices were successfully placed in 96% of patients. Protocol-predicted surgical mortality rate in the HRS and concurrent comparator group was 18.2% and 17.4%, respectively, and Society of Thoracic Surgeons calculator estimated mortality rate was 14.2% and 14.9%, respectively. The 30-day procedure-related mortality rate was 7.7% in the HRS and 8.3% in the comparator group (p = NS). The 12-month survival rate was 76% in the HRS and 55% in the concurrent comparator group (p = 0.047). In surviving patients with matched baseline and 12-month data, 78% had an MR grade of ≤2+. Left ventricular end-diastolic volume improved from 172 ml to 140 ml and end-systolic volume improved from 82 ml to 73 ml (both p = 0.001). New York Heart Association functional class improved from III/IV at baseline in 89% to class I/II in 74% (p < 0.0001). Quality of life was improved (Short Form-36 physical component score increased from 32.1 to 36.1 [p = 0.014] and the mental component score from 45.5 to 48.7 [p = 0.065]) at 12 months. The annual rate of hospitalization for congestive heart failure in surviving patients with matched data decreased from 0.59 to 0.32 (p = 0.034).

CONCLUSIONS:

The MitraClip device reduced MR in a majority of patients deemed at high risk of surgery, resulting in improvement in clinical symptoms and significant left ventricular reverse remodeling over 12 months. (Pivotal Study of a Percutaneous Mitral Valve Repair System.

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Abstract

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BACKGROUND:

Undersized mitral annuloplasty (MA) is the preferred surgical treatment for chronic ischemic mitral regurgitation. However, the preferred shape of undersized MA is unclear.

METHODS:

A previously described finite element model of the left ventricle with mitral valve based on magnetic resonance images of a sheep with chronic ischemic mitral regurgitation after posterolateral myocardial infarction was used. Saddle-shape (Edwards Physio II) and asymmetric (IMR ETlogix) MA rings were digitized and meshed. Virtual annuloplasty was performed using virtual sutures to attach the MA ring. Left ventricular diastole and systole were performed before and after virtual MA of each type.

RESULTS:

Both types of MA reduced the septolateral dimension of the mitral annulus and abolished mitral regurgitation. The asymmetric MA was associated with lower virtual suture force in the P2 region but higher force in P1 and P3 regions. Although both types of MA reduced fiber stress at the left ventricular base, fiber stress reduction after asymmetric MA was slightly greater. Neither type of MA affected fiber stress at the left ventricular equator or apex. Although both types of MA increased leaflet curvature and reduced leaflet stress, stress reduction with saddle-shape MA was slightly greater. Both MA types reduced stress on the mitral chordae.

CONCLUSIONS:

The effects of saddle-shape and asymmetric MA rings are similar. Finite element simulations are a powerful tool that may reduce the need for animal and clinical trials.

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Abstract

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BACKGROUND:

Mitral regurgitation (MR) of mitral valve prolapse predominates in late systole but may be holosystolic or purely mid-late systolic, but the impact of MR timing on MR left ventricular and left atrial consequences and outcome is unknown. Whether effective regurgitant orifice (ERO) by the flow convergence method is similarly linked to outcome in mid-late systolic MR and holosystolic MR is uncertain.

METHODS AND RESULTS:

We comprehensively and prospectively quantified MR in 111 patients with mitral valve prolapse and mid-late systolic MR and matched them to 90 patients with mitral valve prolapse and holosystolic MR for age, gender, atrial fibrillation, ejection fraction, and ERO (flow convergence). Mid-late systolic MR versus holosystolic MR groups were well matched, including for comorbidity, blood pressure, and heart rate (all P>0.10). Mid-late systolic MR versus holosystolic MR caused similar color jet area, midsystolic regurgitant flow, and peak velocity (P>0.40). Despite identical ERO (0.25±0.15 versus 0.25±0.15 cm(2); P=0.53), the shorter duration of mid-late systolic MR (233±56 versus 426±50 ms; P<0.0001) yielded lower regurgitant volume (24.8±13.4 versus 48.6±25.6 mL; P<0.0001). MR consequences, systolic pulmonary pressure, and left ventricular and left atrial volume index (all P<0.001) were more benign in mid-late systolic MR versus holosystolic MR. Under medical management, fewer cardiac events (5 years: 15.8±4.6% versus 40.4±6.1%; P<0.0001) occurred in mid-late systolic MR versus holosystolic MR, requiring less mitral surgery. Multivariable analysis confirmed the independent association of mid-late systolic MR with benign consequences and outcomes (all P<0.01). Absolute ERO was not linked to outcome, in contrast to regurgitant volume.

CONCLUSIONS:

MR of mitral valve prolapse that is purely mid-late systolic causes more benign consequences and outcomes than holosystolic MR. Assessment may be misleading because jet area and ERO by flow convergence appear similar to those of holosystolic MR. However, shorter MR yields lower regurgitant volume, consequences, and benign outcomes. Instantaneous ERO by flow convergence should be interpreted in context, and in mid-late systolic MR, regurgitant volume provides information more reflective of MR severity. Therefore, for clinical management and surgical referral, clinicians should carefully take into account the timing and consequences of MR.

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Abstract

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OBJECTIVES:

The purpose of this study was to characterize patients with mitral regurgitation (MR) and atrial fibrillation (AF) treated percutaneously using the MitraClip device (Abbott Vascular, Abbott Park, Illinois) and compare the results with surgery in this population.

BACKGROUND:

The EVEREST II (Endovascular Valve Edge-to-Edge Repair Study) randomized controlled trial compared a less invasive catheter-based treatment for MR with surgery, providing an opportunity to assess the impact of AF on the outcomes of both the MitraClip procedure and surgical repair.

METHODS:

The study population included 264 patients with moderately severe or severe MR assessed by an independent echocardiographic core laboratory. Comparison of safety and effectiveness study endpoints at 30 days and 1 year were made using both intention-to-treat and per-protocol (cohort of patients with MR ≤2+ at discharge) analyses.

RESULTS:

Pre-existing AF was present in 27% of patients. These patients were older, had more advanced disease, and were more likely to have a functional etiology. Similar reduction of MR to ≤2+ before discharge was achieved in patients with AF (83%) and in patients without AF (75%, p = 0.3). Freedom from death, mitral valve surgery for valve dysfunction, and MR >2+ was similar at 12 months for AF patients (64%) and for no-AF patients (61%, p = 0.3). At 12 months, MR reduction to <2+ was greater with surgery than with MitraClip, but there was no interaction between rhythm and MR reduction, and no difference in all-cause mortality between patients with and patients without AF.

CONCLUSIONS:

Atrial fibrillation is associated with more advanced valvular disease and noncardiac comorbidities. However, acute procedural success, safety, and 1-year efficacy with MitraClip therapy is similar for patients with AF and without AF.

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Abstract

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OBJECTIVE:

Reoperative sternotomy to address mitral valve pathology carries substantial risk, especially with patent bypass grafts or an aortic valve prosthesis. We previously reported our early experience with minimally invasive right thoracotomy and peripheral cannulation as an alternative strategy, and we recently reviewed our cumulative 15-year hospital outcomes with this approach.

METHODS:

Between June 1996 and April 2010, we performed right minithoracotomy for reoperations involving the mitral valve on 167 patients, 85 (51%) of these since 2006. Seventy-one percent had undergone previous coronary artery bypass grafting and 38% a previous valve procedure. Fibrillatory arrest was used in 77% and aortic clamping and root cardioplegia in 23%. Nineteen procedures were performed with robotic assistance.

RESULTS:

Mitral repair frequency increased during each 5-year interval of our experience (1996–2000, 43%; 2001–2005, 53%; 2006–2010, 72%; P = .019), including 80% of native mitral valves without stenosis. Concomitant procedure frequency, most commonly atrial fibrillation ablation, also increased during each 5-year interval (0%, 21%, 48%; P < .0001). Thirty-day mortality was 3.0% (5/167), 0% since 2005. There were no conversions to sternotomy or aortic dissections. Stroke, in 2.4% (4/167), was statistically unrelated to fibrillatory arrest. Increased New York Heart Association functional class (odds ratio, 5.6; 95% confidence interval 1.1–27.8; P = .037) was the only independent predictor of mortality in multivariable analysis.

CONCLUSIONS:

Our updated experience confirmed the effectiveness of minimally invasive right thoracotomy to treat mitral pathology while avoiding reoperative sternotomy risk. We found fibrillatory and cardioplegic arrest methods to be safe myocardial preservation strategies with this approach.

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Abstract

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BACKGROUND:

Long-term follow-up after percutaneous mitral commissurotomy enables predictive factors of late results to be identified.

METHODS AND RESULTS:

Late results of percutaneous mitral commissurotomy were assessed in 1024 consecutive patients. Good immediate results, defined as valve area ≥1.5 cm(2) without mitral regurgitation >2/4, were obtained in 912 patients (89%). These 912 patients were randomly split into 2 cohorts comprising 609 and 303 patients that were used to develop and validate, respectively, a scoring system predicting late functional results. The 20-year rate of good functional results (survival without cardiovascular death, mitral surgery, or repeat percutaneous mitral commissurotomy and in New York Heart Association class I or II) was 30.2 ± 2.0%. A multivariable Cox model identified 7 predictive factors of poor late functional results: higher final mean gradient (P<0.0001), interaction between age and final mitral valve area (P<0.0001) showing that the impact of valve area decreases with age, interaction between sex and valve calcification (P<0.0001) showing that the impact of valve anatomy is stronger in men, and interaction between rhythm and New York Heart Association class showing an impact of New York Heart Association class only in patients in atrial fibrillation (P<0.0001). A 13-point score enabled 3 risk groups to be defined, corresponding to predicted good functional results of 55.1%, 29.1%, and 10.5% at 20 years in the validation cohort.

CONCLUSIONS:

Twenty years after percutaneous mitral commissurotomy in a population of patients with varied characteristics, 30% still had good functional results. Prediction of late functional results is multifactorial and strongly determined by age and the quality of immediate results. A simple validated scoring system is useful for estimating individual patient outcome.

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Abstract

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BACKGROUND:

Whether mitral valve repair during coronary artery bypass grafting (CABG) improves survival in patients with ischemic mitral regurgitation (MR) remains unknown.

METHODS AND RESULTS:

Patients with ejection fraction ≤35% and coronary artery disease amenable to CABG were randomized at 99 sites worldwide to medical therapy with or without CABG. The decision to treat the mitral valve during CABG was left to the surgeon. The primary end point was mortality. Of 1212 randomized patients, 435 (36%) had none/trace MR, 554 (46%) had mild MR, 181 (15%) had moderate MR, and 39 (3%) had severe MR. In the medical arm, 70 deaths (32%) occurred in patients with none/trace MR, 114 (44%) in those with mild MR, and 58 (50%) in those with moderate to severe MR. In patients with moderate to severe MR, there were 29 deaths (53%) among 55 patients randomized to CABG who did not receive mitral surgery (hazard ratio versus medical therapy, 1.20; 95% confidence interval, 0.77-1.87) and 21 deaths (43%) among 49 patients who received mitral surgery (hazard ratio versus medical therapy, 0.62; 95% confidence interval, 0.35-1.08). After adjustment for baseline prognostic variables, the hazard ratio for CABG with mitral surgery versus CABG alone was 0.41 (95% confidence interval, 0.22-0.77; P=0.006).

CONCLUSION:

Although these observational data suggest that adding mitral valve repair to CABG in patients with left ventricular dysfunction and moderate to severe MR may improve survival compared with CABG alone or medical therapy alone, a prospective randomized trial is necessary to confirm the validity of these observations

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Abstract

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BACKGROUND:

Although surgery is indicated in patients with mitral regurgitation (MR) when left ventricular (LV) end-systolic (LVES) dimension is >40 mm, LV ejection fraction may decrease after mitral valve surgery. We hypothesize that significant LV remodeling before surgery is not reflected by standard echocardiographic parameters measured at the base of the heart.

METHODS AND RESULTS:

Ninety-four patients (age, 54 ± 11 years; 38% female) with degenerative isolated MR underwent cine magnetic resonance imaging with tissue tagging and 3-dimensional analysis. In 51 control subjects (age, 44 ± 14 years; 53% female), the relation between LVES volume (LVESV) and LVES dimension was quadratic, whereas in 94 MR patients, this relation was cubic, indicating a greater increase in LVESV per LVES dimension among MR patients. Moreover, magnetic resonance imaging LVESV from summated serial short-axis slices was significantly greater than LVESV assessed with the Bullet formula in MR patients, attributed to a more spherical remodeling distal to the tips of the papillary muscles (P<0.001). Thirty-five patients underwent mitral valve repair per current guideline recommendations. LV ejection fraction decreased from 61 ± 7% to 54 ± 8% (P<0.0001) and maximum shortening decreased significantly below normal at 1 year postoperatively (P<0.0001). Despite normalization of LV stroke volume and LV end-diastolic volume/mass ratio, there was a persistent significant increase in distal LVES 3-dimensional radius/wall thickness ratio and LVESV index after surgery.

CONCLUSIONS:

Despite apparently preserved LVES dimension, MR patients demonstrate significant spherical mid to apical LVES remodeling that contributes to higher LVESV than predicted by standard geometry-based calculations. Decreased LV strain after surgery suggests that a volumetric analysis of LV remodeling and function may be preferred to evaluate disease progression in isolated MR.

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Abstract

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BACKGROUND:

This study investigated whether the timing of mitral valve (MV) repair or surgical approach affects outcomes in patients with MV regurgitation.

METHODS:

Between 1992 and 2009, 2,255 patients underwent MV operations, including 1,305 with isolated MV regurgitation operations (1,054 repairs, 251 replacements). Surgical approaches were sternotomy in 377, video-assisted right minithoracotomy in 481, or robot-assisted in 447. Mean follow-up was 6.4±4.5 years (maximum, 19 years).

RESULTS:

Sternotomy MV repairs decreased during the study while minimally invasive MV repairs increased. Robotic MV repair patients were younger, with fewer women, had better left ventricular ejection fractions, and were more likely to have myxomatous degeneration (all p<0.001). The robotic approach led to a higher MV repair rate and increased use of leaflet/chordal procedures but had longer cardiopulmonary bypass and aortic cross-clamp times (all p<0.001). The 30-day mortality for isolated MV repair was similar for all approaches (p=0.409). Fewer neurological events were observed in the videoscopic and robotic groups (p=0.013). Adjusted survival was similar for all approaches (p=0.357). Survival in patients in New York Heart Association class I to II with myxomatous degeneration or annular dilatation was similar to a matched population but was worse for patients in class III to IV or undergoing MV replacement.

CONCLUSIONS:

MV repair in patients with severe MV regurgitation should be performed before New York Heart Association class III to IV symptoms develop. Minimally invasive MV repair techniques render similar outcomes as the sternotomy approach.

 

Abstract

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BACKGROUND:

While it is known that band annuloplasty for functional mitral regurgitation (FMR) improves leaflet coaptation, the effect on regional coaptation geometry has not previously been well defined. We used three-dimensional transesophageal echocardiography (3D-TEE) to analyze the regional effects of semirigid band annuloplasty on annular geometry and leaflet coaptation zones of patients with FMR.

METHODS:

Sixteen patients with severe FMR underwent a semirigid band annuloplasty. Intraoperative full volume 3D-TEE datasets were acquired pre valve and post valve repair. Offline analysis assessed annular dimensions and regional coaptation zone geometry. The regions were defined as R1 (A1-P1), R2 (A2-P2), and R3 (A3-P3); coaptation distance, coaptation depth, and coaptation length were measured in each region. Differences were analyzed with repeated measures within a general linear model.

RESULTS:

Band annuloplasty decreased mitral regurgitation grade from 3.7 to 0.1 (scale 0 to 4). Annular septolateral dimension (p<0.01) and coaptation distance (p<0.01) decreased significantly in all regions. Likewise, anterior and posterior leaflet coaptation lengths increased in all regions (p<0.01 and p=0.05, respectively), with region 2 showing the greatest increase (p=0.01). Changes in coaptation depth were not significant.

CONCLUSIONS:

Semirigid band annuloplasty for FMR produces significant regional remodeling of leaflet coaptation zones, with region 2 showing the greatest increase in leaflet coaptation length. This regional analysis of annular geometry and leaflet coaptation creates a framework to better understand the mechanisms of surgical success or failure of annuloplasty for FMR.

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Abstract

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BACKGROUND:

Ischemic mitral regurgitation, a complication of myocardial infarction and coronary artery disease more generally, is associated with a high mortality rate and is estimated to affect 2.8 million Americans. With 1-year mortality rates as high as 40%, recent practice guidelines of professional societies recommend repair or replacement, but there remains a lack of conclusive evidence supporting either intervention. The choice between therapeutic options is characterized by the trade-off between reduced operative morbidity and mortality with repair versus a better long-term correction of mitral insufficiency with replacement. The long-term benefits of repair versus replacement remain unknown, which has led to significant variation in surgical practice.

METHODS AND RESULTS:

This article describes the design of a prospective randomized clinical trial to evaluate the safety and effectiveness of mitral valve repair and replacement in patients with severe ischemic mitral regurgitation. This trial is being conducted as part of the Cardiothoracic Surgical Trials Network. This article addresses challenges in selecting a feasible primary end point, characterizing the target population (including the degree of mitral regurgitation) and analytical challenges in this high mortality disease.

CONCLUSIONS:

The article concludes by discussing the importance of information on functional status, survival, neurocognition, quality of life, and cardiac physiology in therapeutic decision making.

 

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Abstract

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OBJECTIVE:

The incidence of recurrent mitral regurgitation (MR) after restrictive annuloplasty (RA) was 5% to 20% in several reports. There are many opinions in favor of adding subvalvular procedures to RA to reduce the tenting forces and improve the repair results.

METHODS:

From March 2003 to May 2010, 55 patients with severe ischemic MR who had undergone papillary muscle (PPM) relocation in conjunction with mitral annuloplasty in our institutions were enrolled. The patients were matched 1:1 with those who underwent isolated RA using the propensity score. The mean left ventricular ejection fraction was 42% ± 6%. The mean tenting area and coaptation depth was 3.2 ± 0.6 cm(2) and 1.3 ± 0.2 cm, respectively. The study endpoints were early mortality and clinical and echocardiographic outcomes, freedom from cardiac-related deaths, and cardiac-related events.

RESULTS:

In-hospital death occurred in 5 patients (4.5%), without a statistically significant difference between the 2 groups (P = .72). The 5-year freedom from cardiac-related deaths and cardiac-related events in the PPM relocation group versus the RA group was 90.9% ± 1.8% versus 89% ± 1.6% (P = .82) and 83% ± 2.1% versus 65.4% ± 1.2% (P < .001), respectively. Recurrent MR equal to or greater than moderate occurred in 2 (3.7%) and 6 (11.5%) patients in the PPM relocation group and RA group (P = .01), respectively. Moreover, we found statistically significant differences for the postoperative mean tenting area and coaptation depth in both groups (P < .001).

CONCLUSIONS:

PPM relocation in conjunction to mitral annuloplasty is an easy and safe method and can be performed without an increase in-hospital mortality. This technique reduced the tenting area and coaptation depth compared with isolated RA, leading to improvement in the incidence of recurrent MR. The PPM group of patients experienced fewer cardiac-related events.

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Abstract

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BACKGROUND:

This was a study to compare the results of mitral valve (MV) repair and MV replacement for the treatment of functional mitral regurgitation (MR) in advanced dilated and ischemic cardiomyopathy (DCM).

METHODS:

One-hundred and thirty-two patients with severe functional MR and systolic dysfunction (mean ejection fraction 0.32 ± 0.078) underwent mitral surgery in the same time frame. The decision to replace rather than repair the MV was taken when 1 or more echocardiographic predictors of repair failure were identified at the preoperative echocardiogram. Eighty-five patients (64.4%) received MV repair and 47 patients (35.6%) received MV replacement. Preoperative characteristics were comparable between the 2 groups. Only ejection fraction was significantly lower in the MV repair group (0.308 ± 0.077 vs 0.336 ± 0.076, p = 0.04).

RESULTS:

Hospital mortality was 2.3% for MV repair and 12.5% for MV replacement (p = 0.03). Actuarial survival at 2.5 years was 92 ± 3.2% for MV repair and 73 ± 7.9% for MV replacement (p = 0.02). At a mean follow-up of 2.3 years (median, 1.6 years), in the MV repair group LVEF significantly increased (from 0.308 ± 0.077 to 0.382 ± 0.095, p < 0.0001) and LV dimensions significantly decreased (p = 0.0001). On the other hand, in the MV replacement group LVEF did not significantly change (from 0.336 ± 0.076 to 0.31 ± 0.11, p = 0.56) and the reduction of LV dimensions was not significant. Mitral valve replacement was identified as the only predictor of hospital (odds ratio, 6; 95% confidence interval, 1.1 to 31; p = 0.03) and overall mortality (hazard ratio, 3.1; 95% confidence interval, 1.1 to 8.9; p = 0.02).

CONCLUSIONS:

In patients with advanced dilated and ischemic cardiomyopathy and severe functional MR, MV replacement is associated with higher in-hospital and late mortality compared with MV repair. Therefore, mitral repair should be preferred whenever possible in this clinical setting.

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Abstract

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BACKGROUND:

The first complete robotic mitral valve repairs (RMVP) and RMVP with CryoMaze (RMVP+C) were done in the United States in May 2000 and October 2003, respectively. We have previously reported our initial 300 isolated RMVPs. Our current study evaluates our consecutive RMVP series, including patients undergoing concomitant atrial fibrillation (AF) cryoablation.

METHODS:

Between May 2000 and April 2010, patients with symptomatic, nonischemic, moderate to severe mitral insufficiency with or without AF were studied. Robotic CryoMaze included both right and left atrial lesion sets. Data were collected prospectively on all patients. Procedures were performed with the three-dimensional da Vinci telesurgical system. Postoperative rhythm was followed up 6 weeks later; 3, 6, and 12 months later, and yearly thereafter with the Cardionet home monitoring system, Holter monitor, and/or serial electrocardiograms. An unpaired two-tailed t test was used for statistical analysis.

RESULTS:

Five hundred forty patients with either 3+ or 4+ mitral insufficiency underwent repair. Of those 540, 454 (84.1%) underwent RMVP and 86 (15.9%) underwent RMVP+C. The patients' mean ages in the RMVP and RMVP+C groups were 56.1 ± 12.9 and 65.6 ± 10.8 years, respectively (mean ± SD) (p < 0.001). Furthermore, mean cardiopulmonary bypass and cross-clamp times for RMVP and RMVP+C were 153.2 ± 37.7 minutes vs. 188.5 ± 53.8 minutes, and 116.6 ± 31.5 minutes vs. 130.6 ± 28.4 minutes, respectively (p < 0.001). Postrepair transesophageal echocardiography showed 447 (82.8%) patients with no mitral insufficiency, 80 (14.8%) with trace, 12 (2.2%) with mild, and 3 (0.6%) with moderate mitral insufficiency. In those who underwent RMVP+C, freedom from AF without taking antiarrhythmic drugs or warfarin was achieved in 96.5% of patients.

CONCLUSIONS:

Although patients were significantly older and operative times were significantly longer for patients having RMVP+C, the results for both successful repair and conversion to sinus rhythm were comparable to published standards. As comfort level is achieved and robotic technology advances, endoscopic repairs and surgical treatment for AF may become a standard.

 

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Abstract

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BACKGROUND:

Limited knowledge exists regarding the forces that act on devices implanted in the mitral annulus. Determining the peak magnitudes, directions, rates, variation throughout the cardiac cycle, and change with left ventricular pressure (LVP) will aid in device development and evaluation.

METHODS:

Novel transducers with the ability to measure forces in the septal-lateral and transverse directions were implanted in six healthy ovine subjects. Forces were measured for cardiac cycles reaching a peak LVP of 90, 125, 150, 175, and 200 mm Hg.

RESULTS:

The septal-lateral force was observed to significantly increase from 3.9 ± 0.8 N (90) to 5.2 ± 1.0 N (125) p < 0.001, 5.9 ± 0.9 N (150) p < 0.001, 6.4 ± 1.2 N (175) p < 0.001, and 6.7 ± 1.5 N (200 mm Hg) p < 0.001. Similarly, the transverse force was seen to increase from 2.6 ± 0.6 N (90) to 3.8 ± 1.0 N (125) p < 0.01, 4.6 ± 1.3 N (150) p < 0.001, 4.3 ± 1.2 N (175) p < 0.001, and 3.5 ± 0.7 N (200 mm Hg) p < 0.05. In comparison, the septal-lateral force was significantly greater than the transverse force at 90 (p < 0.05), 125 (p < 0.05), 175 (p < 0.001), and 200 mm Hg (p < 0.0005).

CONCLUSIONS:

Annular forces and their variations with LVP through the cardiac cycle are described. The results demonstrate differences in force magnitude and rate for increasing levels of LVP between the septal-lateral and transverse directions. These directional differences have strong implications in the development of future mitral devices.

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Abstract

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BACKGROUND:

The experience with mitral valve repair for severe mitral regurgitation in infants was retrospectively reviewed.

METHODS:

From 1978 to 2009, 15 infant patients (4 boys, 7.2±3.2 months old) underwent mitral valve repair for severe mitral regurgitation. The etiology of mitral regurgitation according to Carpentier classification was type I in 1 patient, type II in 10 patients, and type III in 4 patients. Artificial chordal replacement was performed in 11 patients. The follow-up course was completed in all patients, with a median follow-up period of 10.2 years (range, 2.2 to 33.4 years).

RESULTS:

There were no operative or in-hospital mortalities. The actuarial survival and freedom from reoperation rates at 10 years were 89% and 65%, respectively. Five patients required redo mitral valve surgery, including 4 patients needing mitral valve replacement. Three of 4 patients with type III mitral regurgitation, caused by congenital subvalvar structural abnormality, required redo mitral valve surgery. In 11 patients who underwent artificial chordal reconstruction, 2 (18%) required mitral valve replacement during the early postoperative period, whereas the remaining patients showed no recurrent mitral regurgitation during the entire study period. The latest echocardiography findings at 7.3 years after the operation showed that the left ventricular diastolic diameter, mitral valve diameter, and ejection fraction were 99.2%±5.0% of normal, 101.7%±13.3% of normal, and 0.741±0.058, respectively.

CONCLUSION:

Long-term durability of mitral valve repair for severe mitral regurgitation in infants was satisfactory. Artificial chordal reconstruction is an effective procedure without an elevated risk of late reoperation.

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Abstract

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OBJECTIVE:

We evaluated the combined effect of hospital and surgeon volume on operative outcomes of mitral valve surgery in the United States.

METHODS:

The Nationwide Inpatient Sample was used to identify adult patients undergoing isolated mitral valve surgery for mitral regurgitation from 2003 to 2008. Hospitals and surgeons were separately stratified into equal-size tertiles according to annual overall mitral valve operative volumes. Multivariate logistic regression analysis was conducted, adjusting for multiple patient, hospital, and operative data, to determine the separate and combined effects of hospital and surgeon volume on operative outcomes.

RESULTS:

A total of 50,152 eligible patients were identified during the study period. Although both hospital and surgeon volume correlated significantly with operative mortality in separate risk-adjusted analyses, only lower surgeon volume persisted as a significant risk factor in the combined risk-adjusted analysis. Moreover, although hospital volume only accounted for 10.7% of the surgeon volume effect on increased mortality for low-volume surgeons, surgeon volume accounted for 74.5% of the hospital volume effect on increased mortality in low-volume hospitals. Surgeon, but not hospital, volume correlated with inpatient costs. Also, significant trends were seen with repair rates, with increasing surgeon volume demonstrating a relatively stronger correlation with the odds of repair (P < .001) than hospital volume (P = .01).

CONCLUSIONS:

The effect of hospital volume on operative outcomes of mitral valve surgery was largely driven by the individual surgeon volumes within that hospital. Conversely, surgeon volume affected these outcomes independently of hospital volume. Identifying the processes by which higher volume surgeons attain better outcomes in mitral valve surgery would therefore be prudent.

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Abstract

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OBJECTIVE:

The aim of this study was to evaluate the long-term fate of the cryopreserved mitral homograft focusing on structural valve deterioration.

METHODS:

Homograft replacement of the mitral valve was performed in 106 patients. The causes of mitral disease were rheumatic disease (n=75), endocarditis (n=24), and others (n=7). There were 40 partial homografts and 66 total homografts.

RESULTS:

Mean follow-up was 9.3+4.7 years (up to 17.8 years). There were 5 early (< 3 months) and 15 late deaths. There have been 5 early ( < 3 months) and 30 late reoperations. Five patients had endocarditis, and 5 patients had an ischemic/hemorrhagic event. Compared with baseline, follow-up echography showed progression of mitral regurgitation grade (from 0.4 to 1.3; P < .001) with stenosis (elevated gradient: from 3.9 to 7.0 mm Hg; P < .001) and decreased valve area (from 2.3 to 1.7 cm2, P < .001). Freedom from structural valve deterioration was 90%, 76%, and 65% at 5, 10, and 15 years, respectively. Structural valve deterioration was more frequent in total homografts (P=.018 vs partial homografts) and in case of pregnancy (P=.016 vs no pregnancy). Stenosis related to structural valve deterioration was more pronounced for age less than 40 years (P=.03) and ring size 30 mm or less (P=.002). Pathologic analysis of the explanted homografts almost invariably showed dense fibrosis with calcification and no cellularity.

CONCLUSION:

Mitral homografting was accomplished with early echographic results similar to those of valve repair. Structural valve deterioration produced mixed stenosis with insufficiency, and its incidence was comparable to that of bioprostheses structural valve deterioration. An improvement in the preservation mode of valvular homografts is warranted.

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Abstract

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OBJECTIVE:

Right thoracotomy using ventricular fibrillation with cooling has been used for redo mitral valve surgery. This approach avoids the complications of redo sternotomy, such as injury to prior grafts and hemorrhage. As a further refinement, we have used a beating heart technique to further minimize complications while simplifying the operation.

METHODS:

We reviewed the outcomes of 450 patients who underwent redo mitral valve surgery via a right thoracotomy from 1996 to 2011 at the University of Michigan. Of these, 134 patients underwent redo mitral valve surgery with ventricular fibrillation, and 316 patients underwent beating heart surgery. Although operative eras were consecutive, patients' age, risk factors, New York Heart Association, and preoperative left ventricular ejection fraction were not significantly different. Core temperature on cardiopulmonary bypass for beating heart surgery was 32°C versus 26°C for ventricular fibrillation.

RESULTS:

Patients undergoing beating heart surgery had shorter periods of cardiopulmonary bypass: 81±9 minutes versus 113±36 minutes. Beating heart surgery required less blood products than ventricular fibrillation: 1.65±2 units versus 3.8±5 units packed red blood cells, 0.6±1.2 units versus 1.8±4 units fresh-frozen plasma, and 1.02±4 versus 7.5±17 platelet packs (all P<.01). Conversely, patients receiving ventricular fibrillation required longer postoperative ventilation: 34±101 hours versus 15.5±27 hours (P<.01). The 30-day mortality was similar for both (6.5% for beating heart and 7.4% for ventricular fibrillation), and postoperative length of stay was the same at 7 days. Stroke rate was 2.6% for patients undergoing beating heart surgery and 3% for patients receiving ventricular fibrillation. Significant operative complications were uncommon; there was no catastrophic hemorrhage, and only 2 patients receiving ventricular fibrillation and 2 patients undergoing beating heart surgery required reexploration.

CONCLUSIONS:

As reoperative cardiac surgery continues to increase, techniques that safely facilitate operation while improving outcome should be adopted. As an operative alternative, redo right thoracotomy mitral valve surgery on the beating heart is associated with shorter bypass time, less transfusion requirements, shorter postoperative ventilation, and lower mortality. This safe and effective approach should be considered for this complex operation.

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Abstract

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BACKGROUND:

Although mitral valve repair is the recommended treatment for severe mitral regurgitation of degenerative etiology, valve replacement remains common, particularly for complex lesions or anterior leaflet involvement. We sought to characterize the feasibility and outcomes of an "all comers" repair strategy applied systematically in all cases of degenerative mitral valve disease, regardless of age, complexity, or leaflet involvement

METHODS:

From January 2002 to December 2010, 744 consecutive patients (mean age, 58±13 years [range, 12-90]; mean LVEF, 55%±9%) with degenerative mitral valve regurgitation and prolapse (anterior leaflet: n=42, 6%; posterior leaflet: n=556, 75%; bileaflet: n=146, 19%) underwent mitral valve surgery. Annular, leaflet or chordal calcification was present in 27% of cases.

RESULTS:

All patients underwent mitral valve repair and received a concomitant annuloplasty with a median ring size of 32 mm (interquartile range, 30-36). There was 1 early valve replacement (99.9% repair rate) due to atrioventricular groove bleeding and 5 late re-repairs (0.7%) due to disease progression or infective endocarditis. In-hospital mortality and major stroke rates were 0.8% and 0.5%, respectively. Survival rates at 1 and 5 years were 99.2%±0.3% and 97.4%±0.8%, respectively. Seven-year freedom from reoperation was 97.1%±0.6%. The estimate of patients with <3+ mitral regurgitation at 4 and 7 years was 98% and 96%, respectively, and 95% and 91%, respectively, for <2+ mitral regurgitation.

CONCLUSIONS:

A systematic strategy of mitral valve repair that uses a variety of techniques allows repair of all degenerative valves in a reference center, with good short-term outcomes and mid-term durability. Further study is required to document the long-term efficacy of an "all comers" mitral valve repair strategy in degenerative subgroups with very complex valve morphology.

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Abstract

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BACKGROUND:

Little is known about the pathophysiology of myxomatous degeneration of the mitral valve, the pathological hallmark of mitral valve prolapse, associated with symptomatic mitral regurgitation, heart failure, and death. Excess transforming growth factor (TGF)-β signaling is known to cause mitral valve degeneration and regurgitation in a mouse model of Marfan syndrome. We examined if TGF-β signaling is dysregulated in clinical specimens of sporadic mitral valve prolapse compared with explanted nondiseased mitral valves and we tested the effects of angiotensin II receptor blockers on TGF-β signaling in cultured human mitral valve cells.

METHODS AND RESULTS:

Operative specimens, cultured valve tissues, and cultured valvular interstitial cells were obtained from patients with mitral valve prolapse undergoing mitral valve repair or from organ donors without mitral valve disease. Increased extracellular matrix in diseased valve tissue correlated with an upregulation of TGF-β expression and signaling as evidenced by SMAD2/3 phosphorylation. Both TGF-β ligand and signaling mediators colocalized primarily to valvular interstitial cells suggesting autocrine/paracrine activation. In cultured valve tissue, exogenous TGF-β increased basal extracellular matrix production, whereas serological neutralization of TGF-β inhibited disease-driven extracellular matrix overproduction. TGF-β-induced extracellular matrix production in cultured valvular interstitial cells was dependent on SMAD2/3 and p38 signaling and was inhibited by angiotensin II receptor blockers.

CONCLUSIONS:

TGF-β has a profibrotic role in the pathogenesis of sporadic mitral valve prolapse. Attenuation of TGF-β signaling by angiotensin II receptor blockers may represent a mechanistically based strategy to modulate the pathological progression of mitral valve prolapse in patients.

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Abstract

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BACKGROUND:

Information regarding patient selection for mitral valve repair for chronic kidney disease or end-stage renal disease (ESRD) with severe heart failure (HF) as well as outcome is limited.

METHODS AND RESULTS:

We classified 208 patients with advanced HF symptoms (Stage C/D) undergoing mitral valve repair for functional mitral regurgitation into 3 groups: estimated glomerular filtration rate ≥30 mL/min/1.73 m(2) (control group, n=144); estimated glomerular filtration rate < 30 mL/min/1.73 m(2), not dependent on hemodialysis (late chronic kidney disease group, n=45), and ESRD on hemodialysis (ESRD group, n=19; preoperative hemodialysis duration 83 ± 92 months). Follow-up was completed with a mean duration of 49 ± 25 months. Postoperative (1-month) cardiac catheterization showed that left ventricular end-systolic volume index decreased from 109 ± 38 to 79 ± 41, 103 ± 31 to 81 ± 31, and 123 ± 40 to 76 ± 34 mL/m(2), in the control, late chronic kidney disease, and ESRD groups, respectively. Left ventricular end-diastolic pressure decreased, whereas cardiac index increased in all groups with no intergroup differences for those postoperative values. Freedom from mortality and HF readmission at 5 years was 18% ± 7% in late chronic kidney disease (P < 0.0001 versus control, P=0.01 versus ESRD), and 64% ± 12% in ESRD (P=1 versus control) as compared with 52% ± 5% in the control group (median event-free survival, 26, 67, and 63 months, respectively).

CONCLUSIONS:

Mitral valve repair for medically refractory functional mitral regurgitation in patients with advanced HF yielded improvements in left ventricular function and hemodynamics irrespective of preoperative renal function status. Patients with ESRD showed favorable late outcome in terms of freedom from mortality and readmission for HF as compared with those with late chronic kidney disease. Further studies are needed to assess the survival benefits of mitral valve repair in patients with ESRD and advanced HF.

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Abstract

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BACKGROUND:

Proponents of flexible annuloplasty rings have hypothesized that such devices maintain annular dynamics. This hypothesis is based on the supposition that annular motion is relatively normal in patients undergoing mitral valve repair. We hypothesized that mitral annular dynamics are impaired in ischemic mitral regurgitation and myxomatous mitral regurgitation.

METHODS AND RESULTS:

A Philips iE33 echocardiographic module and X7-2t probe were used to acquire full-volume real-time 3-dimensional transesophageal echocardiography loops in 11 normal subjects, 11 patients with ischemic mitral regurgitation and 11 patients with myxomatous mitral regurgitation. Image analysis was performed using Tomtec Image Arena, 4D-MV Assessment, 2.1 (Munich, Germany). A midsystolic frame was selected for the initiation of annular tracking using the semiautomated program. Continuous parameters were normalized in time to provide for uniform systolic and diastolic periods. Both ischemic mitral regurgitation (9.98 ± 155 cm(2)) and myxomatous mitral regurgitation annuli (13.29 ± 3.05 cm(2)) were larger in area than normal annuli (7.95 ± 1.40 cm(2)) at midsystole. In general, ischemic mitral regurgitation annuli were less dynamic than controls. In myxomatous mitral regurgitation, annular dynamics were also markedly abnormal with the mitral annulus dilating rapidly in early systole in response to rising ventricular pressure.

CONCLUSIONS:

In both ischemic mitral regurgitation and myxomatous mitral regurgitation, annular dynamics and anatomy are abnormal. Flexible annuloplasty devices used in mitral valve repair are, therefore, unlikely to result in either normal annular dynamics or normal anatomy.

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Abstract

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BACKGROUND:

In patients with mitral valve prolapse, nonprolapsed leaflets are often apically tented. We hypothesized that secondary left ventricular dilatation attributed to primary mitral regurgitation (MR) causes papillary muscle (PM) displacement, resulting in this leaflet tenting/tethering, and that secondary tethering further exacerbates malcoaptation and contributes to MR severity.

METHODS AND RESULTS:

Three-dimensional transesophageal echocardiography was performed in 25 patients with posterior mitral leaflet prolapse with an intact anterior mitral leaflet (AML) and 20 controls. From 3D zoom data sets, 11 equidistant antero-posterior cut planes of the mitral valve at midsystole were obtained. In each plane, tenting area of nonprolapsed leaflet and prolapse area of prolapsed leaflet were measured. Prolapse/tenting volume of each region was obtained as the product of interslice distance and the prolapse/tenting area. AML tenting volume and whole leaflet prolapse/tenting volume were then obtained. The PM tethering distance between PM tips and anterior mitral annulus was measured from 3D full-volume data sets. The severity of MR was quantified by vena contracta area extracted from color 3D transesophageal echocardiography data sets. AML tenting volume was significantly larger in patients with posterior mitral leaflet prolapse compared with that in controls (1.2 ± 0.5 versus 0.6 ± 0.2 mL/m(2); P < 0.001). Multivariate regression analysis identified independent contribution to AML tenting volume from an increase in PM tethering distance. Multivariate regression analysis identified independent contributions to MR severity (vena contracta area) from both whole leaflet tenting volume (r=0.44; P < 0.05) and prolapse volume (r=0.44; P < 0.05). AML tenting volume decreased along with left ventricular volume and PM tethering distance postrepair (n=8; P < 0.01).

CONCLUSION:

These results suggest that primary mitral valve prolapse with MR causes secondary mitral leaflet tethering with PM displacement by left ventricular dilatation, which further exacerbates valve leakage, constituting a vicious cycle that would suggest a pathophysiologic rationale for early surgical repair.

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Abstract

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BACKGROUND:

We hypothesized that annuloplasty ring implantation alters mitral annular strains in a normal beating ovine heart preparation.

METHODS AND RESULTS:

Sheep had 16 radiopaque markers sewn equally spaced around the mitral annulus. Edwards Cosgrove partial flexible band (COS; n=12), St Jude complete rigid saddle-shaped annuloplasty ring (RSA; n=10), Carpentier-Edwards Physio (PHY; n=11), Edwards IMR ETlogix (ETL; n=11), and GeoForm (GEO; n=12) annuloplasty rings were implanted in a releasable fashion. Four-dimensional marker coordinates were obtained using biplane videofluoroscopy with the ring inserted (ring) and after ring release (control). From marker coordinates, a functional spatio-temporal representation of each annulus was generated through a best fit using 16 piecewise cubic Hermitian splines. Absolute total mitral annular ring strains were calculated from the relative change in length of the tangent vector to the annular curve as strains occurring from control to ring state at end-systole. In addition, average Green-Lagrange strains occurring from control to ring state at end-systole along the annulus were calculated. Absolute total mitral annular ring strains were smallest for COS and greatest for ETL. Strains for RSA, PHY, and GEO were similar. Except for COS in the septal mitral annular segment, all rings induced compressive strains along the entire annulus, with greatest values occurring at the lateral mitral annular segment.

CONCLUSIONS:

In healthy, beating ovine hearts, annuloplasty rings (COS, RSA, PHY, ETL, and GEO) induce compressive strains that are predominate in the lateral annular region, smallest for flexible partial bands (COS) and greatest for an asymmetrical rigid ring type with intrinsic septal-lateral downsizing (ETL). However, the ring type with the most drastic intrinsic septal-lateral downsizing (GEO) introduced strains similar to physiologically shaped rings (RSA and PHY), indicating that ring effects on annular strain profiles cannot be estimated from the degree of septal-lateral downsizing.

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Abstract

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OBJECTIVES:

Transection of the secondary chordae on the anterior leaflet of the mitral valve to relieve leaflet tethering and reduce regurgitation is an experimentally proven procedure to correct functional mitral regurgitation. In the present study, we sought to investigate whether transecting the secondary chordae would have an effect on the marginal chordal force on the same leaflet.

METHODS:

Adult porcine mitral valves (n = 8) were studied in a pulsatile heart simulator, in which the papillary muscle positions can be precisely positioned. Miniature transducers were inserted into the anterior marginal chordae to measure the chordal forces. Each valve was studied under baseline conditions, 3 different tethering conditions (apical, apical-lateral, and apical-lateral-posterior), and after chordal cutting in the 3 tethering conditions. The temporal changes and peak and average marginal chordal forces under each condition are reported.

RESULTS:

Apical tethering increased the marginal chordal force by an average of 96% but remained unchanged after chordal cutting. With apical-lateral tethering, the marginal chordal force increased by 210% from baseline and increased further to 350% of baseline after chordal cutting. After apical-lateral-posterior tethering, the marginal chordal force increased to 335% of baseline before transection and by 548% after transection.

CONCLUSION:

The increase in the marginal chordal force after secondary chordal cutting depends on the location of the papillary muscles and the extent of leaflet tethering. Although chordal cutting might not alter the valve mechanics under minimal leaflet tethering, it significantly affects the mechanics when the leaflet tethering is more pronounced, which is typically seen in patients with functional mitral regurgitation.

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Abstract

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BACKGROUND:

We evaluated the effect of isolated off-pump coronary artery bypass grafting on functional ischemic mitral regurgitation (IMR) associated with acute coronary syndrome.

METHODS:

Of 1,419 acute coronary syndrome patients who underwent coronary revascularization between 2000 and 2010 (1,324 off-pump and 95 on-pump), 59 OPCAB patients had greater than mild degree functional IMR preoperatively (31 mild to moderate, 23 moderate, 5 severe). Clinical outcomes and results from echocardiography, angiography, and myocardial single-photon emission computed tomography performed early and 1 year postoperatively were analyzed.

RESULTS:

Operative mortality was 5.1% (3 of 59). All survivors underwent early postoperative echocardiograms, which showed 0 patients with worsened IMR; 41 with less than or equal to mild degree residual IMR (NMR group); and 15 with greater than mild degree IMR (RMR group). Myocardial single-photon emission computed tomography revealed that RMR patients had more reversible ischemic myocardial segments preoperatively than NMR patients (p=0.009). Successful right coronary revascularization with proven graft patency was a predictor of early improvement of IMR (p=0.024). There were no differences in postoperative morbidities between the 2 groups. One-year follow-up echocardiograms demonstrated further improvement in 10 of 13 RMR patients. No patients experienced mitral valve-related events during follow-up. Overall survival and major adverse cardiac event-free survival rates at 5 years were 84.6% and 78.1%, respectively, with no intergroup differences.

CONCLUSIONS:

Most functional IMR associated with acute coronary syndrome, including severe degree IMR, improved during the first postoperative year after off-pump coronary artery bypass grafting.

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Abstract

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BACKGROUND:

We investigated predictive factors of postoperative recurrence of mitral regurgitation (MR) after mitral valve annuloplasty for functional ischemic MR.

METHODS:

This study was a retrospective review of patients with functional MR who underwent mitral ring annuloplasty at our institution from 1998 to 2008. Records were reviewed for perioperative variables, including echocardiographic measurements. Recurrence was defined as MR grade moderate (3+) or greater on any postoperative echocardiogram.

RESULTS:

Of 548 patients who underwent mitral annuloplasty for functional MR, echocardiogram reports were available for review for 250. These patients comprised the study cohort. There were 154 patients with concomitant coronary artery bypass grafting. The left ventricular (LV) end-diastolic (LVED) index was calculated by dividing the LVED dimension by body surface area (BSA). A high LVED index (>3.5 cm/m2) was predictive of MR recurrence (p=0.047): the recurrence rate was 20.3% (13 of 64) in high-index patients and 10.2% (19 of 186) in low-index (<3.5 cm/m2) patients. Median recurrence-free survival was 35 months (range, 19 to 59 months) in high-LVED-index patients and 46.5 months (range, 22 to 75 months) in low-LVED-index patients (p=0.048). Preoperative MR severity and LV ejection fraction were not predictive of MR recurrence.

CONCLUSIONS:

Careful analysis of the preoperative echocardiogram using a novel, easily calculated variable, the LVED index, may help identify patients who are at greater risk for MR recurrence and reduced survival. Such information could prompt consideration of alternative or additional interventions in these patients.

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Abstract

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BACKGROUND:

The role of mitral valve repair (MVR) during coronary artery bypass grafting (CABG) in patients with moderate ischemic mitral regurgitation (MR) is uncertain. We conducted a randomized, controlled trial to determine whether repairing the mitral valve during CABG may improve functional capacity and left ventricular reverse remodeling compared with CABG alone.

METHODS AND RESULTS:

Seventy-three patients referred for CABG with moderate ischemic MR and an ejection fraction >30% were randomized to receive CABG plus MVR (34 patients) or CABG only (39 patients). The study was stopped early after review of interim data. At 1 year, there was a greater improvement in the primary end point of peak oxygen consumption in the CABG plus MVR group compared with the CABG group (3.3 mL/kg/min versus 0.8 mL/kg/min; P<0.001). There was also a greater improvement in the secondary end points in the CABG plus MVR group compared with the CABG group: left ventricular end-systolic volume index, MR volume, and plasma B-type natriuretic peptide reduction of 22.2 mL/m(2), 28.2 mL/beat, and 557.4 pg/mL, respectively versus 4.4 mL/m(2) (P=0.002), 9.2 mL/beat (P=0.001), and 394.7 pg/mL (P=0.003), respectively. Operation duration, blood transfusion, intubation duration, and hospital stay duration were greater in the CABG plus MVR group. Deaths at 30 days and 1 year were similar in both groups: 3% and 9%, respectively in the CABG plus MVR group, versus 3% (P=1.00) and 5% (P=0.66), respectively in the CABG group.

CONCLUSIONS:

Adding mitral annuloplasty to CABG in patients with moderate ischemic MR may improve functional capacity, left ventricular reverse remodeling, MR severity, and B-type natriuretic peptide levels, compared with CABG alone. The impact of these benefits on longer term clinical outcomes remains to be defined.

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Abstract

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OBJECTIVE:

The data on echocardiographic evaluation of mitral durability after rheumatic mitral repair is scarce.

METHODS:

total of 193 patients (mean age, 39.4 ± 12.8 years; 154 females) who underwent mitral valve repair for rheumatic valve disease from 1997 to 2010 were included in the study. A Maze operation was performed in 90.3% (n = 102) of the patients with atrial fibrillation (n = 113). Survival, valve-related complications, and echocardiographic data were evaluated.

RESULTS:

Mitral regurgitation was the predominant disease in 75.6% of patients (n = 146). There was one early death (0.5%) . During the mean follow-up period of 76.7 ± 45.6 months, there were 9 late deaths and 5 mitral reoperations. Valve-related, event-free survival at 10 years was 85.5% ± 3.3%. In serial postoperative echocardiographic evaluations (mean follow-up duration, 53.7 ± 43.5 months), 40 patients showed either mitral regurgitation (>mild; n = 31) or mitral stenosis (mitral valve area ≤1.5 cm(2); n = 9). At 10 years, 66.4% ± 5.4% of the patients did not have moderate to severe mitral dysfunction. By multivariate analysis, no Maze operation for atrial fibrillation was an independent predictor of mitral dysfunctions (hazard ratio, 3.72; 95% confidence interval, 1.47-9.42; P = .005), whereas the presence of hypertension had borderline significance (hazard ratio, 3.15; 95% confidence interval, 0.96-10.38; P = .059).

CONCLUSIONS:

Although rheumatic mitral repair showed excellent long-term clinical outcomes, a significant proportion of patients experienced moderate to severe mitral dysfunctions postoperatively. Atrial fibrillation without a Maze procedure increased significantly the risks of mitral dysfunctions and adverse outcomes. Therefore, routine performance of a Maze procedure is warranted in the presence of atrial fibrillation whenever possible.

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Abstract

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BACKGROUND:

Percutaneous edge-to-edge mitral valve (MV) repair is a potential therapeutic option for patients presenting with mitral regurgitation, who may not be suitable for surgery. We characterized the edge-to-edge repair forces in a posterior leaflet flail MV model to identify potential modes of mechanical failure.

METHODS:

Porcine MVs were evaluated in two different sizes (Physio II 32 and 40) in a left-side heart simulator under physiologic hemodynamic conditions. Edge-to-edge repair was simulated by suturing miniature force transducers near the free edge of the anterior and posterior leaflets, on the ventricular side, resulting in a double orifice MV. Posterior leaflet flail was created by selective chordal cutting.

RESULTS:

Chordal cutting resulted in posterior leaflet flail and mitral regurgitation; all valves coapted normally before chordal cutting. Peak systolic control forces (size 32, 0.098 ± 0.058 N; size 40, 0.236 ± 0.149 N) were not significantly different from systolic flail forces (size 32, 0.136 ± 0.107 N; size 40, 0.220 ± 0.128 N) for either MV size. No correlation was observed between force magnitude and flail height or width. Peak systolic force was greater (p = 0.08) for the larger MVs (size 40 compared with size 32). Finally, peak diastolic force was significantly smaller (p = 0.04) than peak systolic force regardless of valve size.

CONCLUSIONS:

For the first time, forces imparted on an edge-to-edge MV repair were quantified for a posterior leaflet flail model. Force magnitude was not significantly altered with flail compared with control; it was greatest during peak systole and increased with valve size.

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Abstract

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BACKGROUND:

We evaluated the papillary muscle systolic dyssynchrony (DYS-PAP) using two-dimensional speckle tracking echocardiography (2D-STE) in patients with chronic ischemic mitral regurgitation (CIMR) showing different preoperative leaflet pattern and investigated the impact of baseline tethering pattern in the prediction of significant post-repair desynchronized papillary muscle contraction

METHODS:

We recruited 152 CIMR consecutive patients (64.4% male, mean age 65.9 ± 7.1 years) who survived coronary artery bypass grafting (CABG) and (undersized mitral ring annuloplasty, performed between 2001and 2010. The assessment of DYS-PAP was performed preoperatively and at follow-up (median 41.5 months [IQR 23-61]) by 2D-STE in the apical 4-chamber view for anterolateral papillary muscle and apical long-axis view for posteromedial papillary muscle). Based on the cutoff value (anterior-posterior tethering angle ratio α/β ≥ 0.76) patients were classified in 2 groups; symmetrical (group 1, n = 73, mean α/β = 0.81 ± 0.6) and asymmetrical preoperative tethering pattern (group 2, n = 79, mean α/β = 0.66 ± 0.4).

RESULTS:

Recurrent MR occurred in 67.1% (n = 49) in group 1 versus 3.8% (n = 3) in group 2 (p < 0.001). Comparing both groups at baseline, patients in group 1 had higher DYS-PAP (57.7 ± 5.3 vs 29.8 ± 2.4 ms in group 2, p < 0.001) that significantly worsened at follow-up (78.1 ± 8.8 ms, p < 0.001 versus baseline), whereas in group 2 it improved (26.6 ± 6.0 ms, p < 0.001 versus baseline). Tethering symmetry significantly correlated with DYS-PAP (r = 0.90, p < 0.001) and it was a strong multivariable predictor of significant postoperative DYS-PAP (odds ratio 4.2; 95% confidence level 3.4 to 5.2, p < 0.001).

CONCLUSIONS:

Tethering symmetry is an easy and immediate tool to identify CIMR patients with advanced DYS-PAP who are unlikely to benefit from mitral repair with undersized mitral ring annuloplasty.

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Abstract

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BACKGROUND:

Within the field of cardiac surgery, several strategies have been adopted in an effort to address contributors to increasing health care costs. Limited data are available on cost analysis within the field of mitral valve surgery. The purpose of our investigation was to analyze cost differences between mitral valve repair and replacement.

METHODS:

The analysis was based on the subset of patients with isolated mitral valve repair or replacement (International Classification of Diseases, ninth revision, clinical codes 35.12, 35.23, and 35.24) using data from the 2005 to 2008 Nationwide Inpatient Sample database, which is the largest all-payer database in the United States. We examined the selective contribution of patient demographics, hospital characteristics, and postoperative complications to cost by using hierarchical linear mixed models. We used mixed effects logistic regression models to identify factors that influence extreme cost expenditures in patients undergoing mitral valve surgery.

RESULTS:

Independent predictors of increased cost for both repair and replacement on multivariable analysis included increased age, prior myocardial infarction, heart failure, neurologic deficit, renal disease, emergent status, and Medicare or Medicaid insurance type. The presence of postoperative complications also predicted increased costs. However, the model for repair only yielded a reduction in variability of 13%, while the model for replacement produced a reduction of 22%.

CONCLUSIONS:

In this analysis, the most important contributors to cost for mitral valve repair and replacement are preoperative patient comorbidities, most notably history of myocardial infarction and heart failure, emergent admission status, and postoperative complications. The variables in our model failed to account for a large proportion of the variability in cost. This would suggest that future analyses exploring differential procedure costs between hospitals must look for factors beyond patient baseline characteristics and postoperative outcomes

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Abstract

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BACKGROUND:

Restoring leaflet coaptation is the primary objective in repair of ischemic mitral regurgitation (IMR). The common practice of placing an undersized annuloplasty ring partially achieves this goal by correcting annular dilation; however, annular reduction has been demonstrated to exacerbate posterior leaflet tethering. Using a sheep model of IMR, we tested the hypothesis that posterior leaflet augmentation (PLA) combined with standard annuloplasty sizing increases leaflet coaptation more effectively than undersized annuloplasty alone.

METHODS:

Eight weeks after posterobasal myocardial infarction, 15 sheep with 2+ or greater IMR underwent annuloplasty with either a 24-mm annuloplasty ring (24-mm group, n = 5), 30-mm ring (30-mm group, n = 5), or 30-mm ring with concomitant augmentation of the posterior leaflet (PLA group, n = 5). Using three-dimensional echocardiography, postrepair coaptation zone and posterior leaflet mobility were assessed.

RESULTS:

Leaflet coaptation length after repair was greater in the PLA group (4.1 ± 0.3 mm) and the 24-mm group (3.8 ± 0.5 mm) as compared with the 30-mm group (2.7 ± 0.6 mm, p < 0.01). Leaflet coaptation area was significantly greater in the PLA group (121.5 ± 6.6 mm(2)) as compared with the 30-mm group (77.5 ± 17.0 mm(2)) or the 24-mm group (92.5 ± 17.9 mm(2), p < 0.01). Posterior leaflet mobility was significantly greater in the PLA group as compared with the 30-mm group or the 24-mm group.

CONCLUSIONS:

Posterior leaflet augmentation combined with standard-sized annuloplasty enhances leaflet coaptation more effectively than either standard-sized annuloplasty or undersized annuloplasty alone. Increased leaflet coaptation after PLA provides redundancy to IMR repair, and may decrease incidence of both recurrent IMR and mitral stenosis.

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Abstract

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BACKGROUND:

Mitral valve (MV) repair is performed with less frequency than MV replacement in older persons, with referral often delayed until symptoms are severe. Surgical practice in this population remains inconsistent in the absence of national MV repair outcomes. The goal of this study was to assess durability and longitudinal outcomes after isolated primary MV repair in patients aged 65 years or more.

METHODS:

We linked clinical data from The Society of Thoracic Surgeons adult cardiac surgery database (STS) to longitudinal claims data from the Centers for Medicare and Medicaid Services (CMS). Between January 1991 and December 2007, we identified 14,604 isolated nonemergent primary MV repair operations in STS-CMS data. These were longitudinally examined for mortality, mitral reoperation, and readmissions for heart failure, bleeding, and stroke. Predictors of 5-year death after MV repair were identified using Cox proportional hazard modeling.

RESULTS:

The study cohort had a mean age of 73.3±5.5 years, ejection fraction 54.0%±12.9%; 55.8% (8,148 of 14,604) were female; and 8.4% (1,233 of 14,604) were non-Caucasian. Operative mortality was 2.59% (378 of 14,604). Mean follow-up was 5.9±3.9 years (range, 1.0 to 18.0). Survival during follow-up was 74.9% (10,934 of 14,604). The number of observed events for mitral reoperation, heart failure, bleeding, and stroke were 552 of 14,604 (3.7%), 2,681 of 14,604 (18.4%), 1,051 of 14,604 (7.2%), and 1,131 of 14,604 (7.7%), respectively. The 10-year Kaplan-Meier event rates for mitral reoperation, heart failure, bleeding, and stroke were 6.2%, 30.1%, 15.3%, and 16.4%, respectively. The 10-year actuarial survival of 57.4% was equivalent to the matched US population.

CONCLUSIONS:

Utilizing linked STS and CMS databases, we demonstrate that MV repair is a safe and durable long-term option for older patients. Survival restored to the normal population suggests repair may suppress the longitudinal impact of mitral regurgitation in the elderly and that the practice of delayed referral should be reevaluated. These data provide a contemporary longitudinal benchmark of MV repair outcomes.

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Abstract

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BACKGROUND:

We have previously reported our 3-step repair for obstructive hypertrophic cardiomyopathy (HCM) consisting of resection of the septum, horizontal plication of the anterior mitral leaflet (AML), and release of abnormal papillary muscle attachments. This article reviews our complete experience with surgical management of HCM to better understand the role and relevance of mitral plication.

METHODS:

From 1997 to 2011, 132 patients with HCM underwent surgical treatment at our institution. Eighty-two patients (62%) received AML plication based on selection criteria and were classified as group A; patients in group B did not receive plication. All patients underwent preoperative and postoperative echocardiography. Long-term clinical follow-up was obtained by review of scheduled echocardiograms and direct patient interview.

RESULTS:

The average age of all patients was 55.5 years. Operative mortality was 0%. The mean left ventricular outflow tract (LVOT) gradient decreased from 118±41 mm Hg to 6±13 mm Hg (p < 0.0001). Mean mitral regurgitation improved from 2.4±1.0 to 0.5±0.7 (p < 0.0001). Postoperatively, 96.2% of patients had no residual systolic anterior motion (SAM). Significant improvements in heart failure classification and quality of life scores were noted for all patients. Comparison of groups A and B showed no statistically significant differences in outcomes, complications, or survival. Survival at 1, 5, and 10 years was 98%, 98%, and 92%, respectively.

CONCLUSION:

The heterogeneity of the pathologic process in HCM supports detailed analysis of the septum, mitral leaflets, and subvalvular apparatus. Surgical management of HCM that includes horizontal plication of a lax and elongated AML is safe and results in durable clinical and echocardiographic improvement.

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Abstract

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BACKGROUND:

Undersized ring annuloplasty for ischemic mitral regurgitation (MR) is associated with variable results and >30% MR recurrence. We tested whether subvalvular repair by severing second-order mitral chordae can improve annuloplasty by reducing papillary muscle tethering.

METHODS:

Posterolateral myocardial infarction known to produce chronic remodeling and MR was created in 28 sheep. At 3 months, sheep were randomized to sham surgery versus isolated undersized annuloplasty versus isolated bileaflet chordal cutting versus the combined therapy (n=7 each). At baseline, chronic myocardial infarction (3 months), and euthanasia (6.6 months), we measured left ventricular (LV) volumes and ejection fraction, wall motion score index, MR regurgitation fraction and vena contracta, mitral annulus area, and posterior leaflet restriction angle (posterior leaflet to mitral annulus area) by 2-dimensional and 3-dimensional echocardiography. All groups were comparable at baseline and chronic myocardial infarction, with mild to moderate MR (MR vena contracta, 4.6±0.1 mm; MR regurgitation fraction, 24.2±2.9%) and mitral annulus dilatation (P<0.01). At euthanasia, MR progressed to moderate to severe in controls but decreased to trace with ring plus chordal cutting versus trace to mild with chordal cutting alone versus mild to moderate with ring alone (MR vena contracta, 5.9±1.1 mm in controls, 0.5±0.08 with both, 1.0±0.3 with chordal cutting alone, 2.0±0.4 with ring alone; P<0.01). In addition, LV end-systolic volume increased by 108% in controls versus 28% with ring plus chordal cutting, less than with each intervention alone (P<0.01). In multivariate analysis, LV end-systolic volume and mitral annulus area most strongly predicted MR (r(2)=0.82, P<0.01).

CONCLUSIONS:

Comprehensive annular and subvalvular repair improves long-term reduction of both chronic ischemic MR and LV remodeling without decreasing global or segmental LV function at follow-up.

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Abstract

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BACKGROUND:

Mitral valve (MV) surgical procedures in the elderly are associated with profound operative and long-term mortality. We report our experience and results for MV surgical procedures in the elderly, especially with regard to the influence of comorbidities.

METHODS:

Our hospital database was assessed to identify all patients who underwent MV surgical procedures at the age of 70 years and older between 1999 and 2009. The data were retrospectively analyzed.

RESULTS:

A total of 2,503 patients operated on during this 10-year period were identified. In 97% of patients, mitral regurgitation (MR) was the primary indication for operation, followed by coronary artery disease in 41.6% and aortic valve stenosis in 21.3%. The 30-day mortality rate was 3.1%, and the long-term survival at 5 years was 55.2% (95% confidence interval, 52.3% to 57.5%). Coronary artery bypass grafting was identified to be associated with inferior short-term and long-term survival. Numerous comorbidities significantly influenced long-term survival. The observed mortality was significantly lower than predicted by EuroSCORE (17.2%).

CONCLUSIONS:

MV operations in the elderly can be performed with a low early mortality and promising long-term survival. However, our large series demonstrates that comorbidities are to be attributed as the real burden for successful treatment of elderly patients undergoing MV procedures.

 

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