Surgical Strategies for Management of Mitral Regurgitation: Recent Evidence from Randomized Controlled Trials

In contrast to mitral regurgitation (MR) caused by structural abnormality of the valve ("primary" MR), about which there is increasing consensus regarding treatment, there is increasing controversy around the management of functional or "secondary" MR, of which "ischemic mitral regurgitation" (IMR) is a common cause. While the trend in the management of primary MR is increasingly aggressive, with wide agreement on the preference for repair over replacement such that debate centers on earlier and earlier repair even among asymptomatic patients, the situation is reversed in the setting of secondary MR with uncertainly beyond the mode of management (repair or replacement) to the value of intervening at all. This is, in part, because the term IMR has been somewhat loosely applied by the medical and surgical communities to include regurgitation secondary to active myocardial ischemia, as well as that resulting from a completed myocardial infarct. As a result, there is considerable variability in reported outcomes of surgical interventions for IMR. In addition, the natural history of IMR is quite adverse-more so than that of many solid organ malignancies-and its surgical treatment has traditionally carried a higher operative mortality than many cardiac surgical procedures, including similar operations for primary MR and incidental coronary artery disease. Added to this, with recent advances in both the medical and surgical treatment of heart failure improving nonoperative outcomes and simultaneously reducing operative risk compared to reports from previous decades, the landscape has been quite dynamic. Here, we review the issues surrounding surgical treatment for IMR, along with available evidence supporting different approaches, to lend an informed perspective on the divergent opinions among experts in this field and guide the appropriate management of the individual patient.