Functional mitral regurgitation affects a substantial proportion of patients with congestive heart failure due to myocardial infarction or dilated cardiomyopathy. Functional mitral regurgitation greatly increases morbidity and mortality. Surgical annuloplasty is the standard of care for symptomatic patients with moderate or severe functional mitral regurgitation; however, a large number of patients are refused surgery. Several percutaneous approaches have been developed to address the need for less invasive treatment of mitral annulus dilatation. Devices using coronary sinus to cinch the mitral annulus are relatively easy to use; however, a number of factors may limit their clinical application, such as suboptimal anatomical relationship between the coronary sinus and mitral annulus, risk of coronary artery compression, large variability in the coronary venous anatomy and conflict with other therapies such as ablation or cardiac resynchronisation. Direct mitral annuloplasty is anticipated to be more effective than the coronary sinus approaches; however, it has yet to prove its safety and efficacy in carefully designed clinical trials. The best candidates and the best timing for each percutaneous mitral annuloplasty therapy, whether direct or indirect, have yet to be identified.
