Percutaneous mitral valve repair: the necessity to redefine secondary mitral regurgitation

Interest in percutaneous mitral valve repair has increased during recent years. This is mainly driven by the significant number of patients being declined for mitral valve surgery because of a high risk of surgery-related complications or death. In this subset of patients, percutaneous edge-to-edge repair using the MitraClip device (Abbott, Menlo Park, CA, USA) has become an established treatment option, proven to be safe, efficient and associated with improved functional status. In contrast to primary mitral regurgitation (MR), clinical outcomes after mitral valve surgery appear to be less favourable as regards secondary MR due to heart failure. In the MITRA-FR and COAPT trials, patients with moderate to severe and severe secondary MR with reduced left ventricular function received either medical treatment (control group) or MitraClip implantation plus medical treatment (device group). Results were conflicting, with only the COAPT trial showing better clinical outcomes in the device group. However, both trials are now seen as complementary and provide useful information especially regarding patient selection for MitraClip therapy. The goal of this review is to delineate which subset of patients with secondary MR will potentially benefit from percutaneous mitral valve repair.