Atrial functional versus ventricular functional mitral regurgitation: Prognostic implications

Background: Atrial functional mitral regurgitation (FMR) occurs because of left atrial dilatation or atrial fibrillation in heart failure with preserved left ventricular (LV) function, contrary to ventricular FMR, which occurs because of LV dysfunction. Despite pathophysiological differences, current guidelines do not discriminate between these 2 entities. Methods: From January 2002 to March 2019, all adult patients with >= 3+ mitral regurgitation who underwent mitral valve repair or replacement were identified. Postoperative outcomes and midterm time-to-event rates (survival and reoperation) were compared. Results: Overall, 94 atrial FMR (mean age, 67.6 years) and 84 ventricular FMR (mean age, 64 years) patients met inclusion criteria. Differences in baseline cardiac morphology and function of the atrial FMR and ventricular FMR patients were as follows: concomitant atrial fibrillation (37.2% vs 14.3%), heart failure (42.6% vs 63.1%), LV ejection fraction (60% vs 37%), at least moderate LV dilation (4.8% vs 40.6%), and moderate/severe right heart dysfunction (15.2% vs 5.1%), respectively. Operative mortality was 0% in the atrial FMR versus 1.2% in the ventricular FMR cohort. Actuarial estimates of survival and freedom from reoperation at 5 and 10 years was significantly higher in the atrial FMR cohort versus the ventricular FMR cohort. Ventricular FMR also remained a significant predictor of midterm mortality in our risk-adjusted analysis (adjusted hazard ratio for ventricular FMR, 1.8; 95% confidence interval, 1.001-3.26). Conclusions: There are important differences in baseline characteristics in terms of cardiac morphology and function among atrial FMR and ventricular FMR patients, which appear to affect in-hospital and midterm outcomes. Because of these discrepancies, early discrimination between these 2 etiologies of FMR might facilitate more tailored approaches to management.