Atrial functional mitral regurgitation in cardiology and cardiac surgery

Functional or secondary mitral regurgitation (MR) is a clear and present danger to cardiovascular health, with heightened morbidity and mortality rates. Secondary MR is caused by an imbalance between two sets of forces. There are two forces at play here. One keeps the mitral leaflets tethered, while the other closes them. The evidence clearly shows inadequate coaptation. Functional MR (FMR) is the typical form of MR. It is almost always caused by dysfunction and alterations of the left ventricle (LV) geometry. It occurs in both ischemic and non-ischemic disease states. Atrial FMR (AFMR) is a disease that has only recently come to be acknowledged. This phenomenon arises when mitral annular enlargement is caused by left atrial enlargement. This preserves the geometry and function of the LV. AFMR is most frequently encountered in individuals with chronic atrial fibrillation or heart failure, in whom a normal ejection fraction is present. Published studies and ongoing research vary in their definition of AFMR, but there is no doubt that AFMR exists. This review definitively explains the pathophysiology of AFMR and demonstrates the necessity of a common working standard for the definition of AFMR. This is essential to warrant cohesiveness in the data reported and to drive forward the much-needed research into the outcomes and treatment strategies in this critical field. A number of high-quality studies have demonstrated that restrictive mitral annuloplasty and transcatheter procedure based on edge-to-edge repair are effective in reducing MR and alleviating symptoms. The pathophysiology, echocardiographic diagnosis, and treatment of AFMR are thoroughly reviewed in this comprehensive review.