Acute ischemic mitral regurgitation complicating myocardial infarction
Emergent surgical intervention in patients with severe mitral regurgitation due to papillary muscle rupture (type II dysfunction) is almost always indicated. These patients should benefit from an early and aggressive medical therapy to optimize their prognosis. The principal goal of preoperative medical management is hemodynamic stabilization (preservation of cardiac output and arterial pressure to maintain peripheral organ perfusion as well as the preservation of coronary blood flow). This is best achieved with prompt insertion of an intra-aortic balloon pump and the use of moderate dose of inotropic agents. This stabilization phase, however, should not delay surgical management of these critically ill patients. It is critical to perform a coronary angiography in these patients prior to surgical intervention as combined coronary revascularization and mitral valve surgery is associated with improved long-term survival compared to mitral surgery alone.
Severe acute mitral regurgitation in patients with type IIIb dysfunction can often be treated medically in combination with the insertion of an intra-aortic balloon pump and early percutaneous revascularization. The severity of mitral regurgitation gradually decreases during the post-infarction recovery period. Occasionally, despite appropriate and maximal medical therapy, low cardiac output and cardiogenic shock persist indicating the need for surgical correction of mitral regurgitation. In some of these cases, left ventricular dysfunction is extremely severe and unlikely to recover and the insertion of a left ventricular assist device appears the preferred surgical option.
Mild to moderate acute ischemic mitral regurgitation is best treated medically and does not require surgical intervention. In some patients, early percutaneous interventional therapy plays a key role in reversing mitral regurgitation.
Chronic ischemic mitral regurgitation
Most patients with moderate to severe chronic type IIIb ischemic mitral regurgitation have symptoms of congestive heart failure or worsening left ventricular function. In addition, they often have severe 3-vessel coronary artery disease. Medical management of these patients is associated with poor clinical outcomes. These patients should undergo a combined mitral valve reconstruction and myocardial revascularization, provided that the operative mortality remains acceptable within a range of 2 to 4%.
Patients with mild to moderate type IIIb mitral regurgitation should undergo mitral valve reconstruction if they are referred for myocardial revascularization. Several clinical studies have shown that coronary artery bypass grafting alone does not completely reverse ischemic mitral regurgitation. In addition, it has also been shown that the persistence of the latter condition is associated with reduced long-term survival and an increased incidence of congestive heart failure, thus the recommendation for a combined surgical procedure.
It is important to stress that no clinical studies have shown a survival benefit in patients undergoing mitral valve reconstruction for type IIIb ischemic mitral regurgitation. Several reports have, however, demonstrated an improvement in clinical symptoms following the surgical correction of this disorder. All this information indicates the need for a randomized trial to study the potential survival benefit after the surgical treatment of type IIIb ischemic mitral regurgitation.
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