• mitral valve insufficiency
• atrial fibrillation
• heart failure

Functional mitral regurgitation (FMR) is a common problem, especially in patients with heart failure. Conventional FMR caused by left ventricular (LV) dilatation or LV dysfunction and mitral valve tethering (termed ventricular FMR (VFMR)) is widely recognised. However, with the ageing of the heart failure population, the concept of atrial FMR (AFMR) caused by left atrial (LA) enlargement but with normal LV size and function was recently proposed.1 Although AFMR generally occurs in patients with atrial fibrillation (AF) and/or heart failure with preserved ejection fraction (HFpEF), little is known about its pathophysiology, epidemiology, prognosis and treatment options.2

Sébastien Deferm and colleagues3 report the efficacy of mitral valve annuloplasty (MVA) for patients with AFMR (n=97) compared with those with VFMR (n=119). They defined AFMR as mitral regurgitation (MR) caused by isolated annular dilatation in the absence of intrinsic valvular and LV disease, with invariably normal LV volume and global/regional systolic function (ie, LV ejection fraction (LVEF) ≥50%). VFMR also included patients with subvalvular leaflet tethering, with reduced LVEF (<50%) and/or global or regional alterations in LV geometry. They showed that patients with AFMR were typically women, with a history of AF and with a larger LA size compared with patients with VFMR. During a follow-up of 3.3 years, prognosis after MVA for treatment of AFMR was better than that after MVA for treatment of VFMR, as reflected by lower all-cause mortality and recurrence of moderate or greater MR independent of baseline differences. This is the first study to show the long-term efficacy of MVA for AFMR.

Since first described by Gertz et al,1 AFMR has been widely discussed as a new concept. However, even the definition of AFMR remains ambiguous. According to this issue of Heart and several studies, the …