Severe Atrial Functional Mitral Regurgitation: Clinical and Echocardiographic Characteristics, Management and Outcomes

Objectives: This study was designed to compare the clinical and echocardiographic characteristics, management, and outcomes of severe atrial functional mitral regurgitation (AFMR) to primary mitral regurgitation (PMR).

Background: AFMR remains poorly defined clinically.

Methods: Consecutive patients who underwent transesophageal echocardiography at our institution between 2011 and 2018 for severe mitral regurgitation with preserved left ventricular function were screened. We excluded patients with endocarditis, any form of cardiomyopathy, or prior mitral intervention. The absence of leaflet pathology defined AFMR. Outcomes included death and heart failure hospitalizations.

Results: A total of 283 patients were included (AFMR = 14%, PMR = 86%). Compared to PMR, patients with AFMR had more comorbidities, including hypertension (94.9% vs. 76.2%; p = 0.015), diabetes mellitus (46.2% vs. 18.4%; p < 0.001), long-standing atrial fibrillation (28.2% vs. 13.1%; p = 0.015), prior nonmitral cardiac surgery (25.6% vs. 9.8%; p = 0.004), and pacemaker placement (33.3% vs. 13.5%; p = 0.002). They also had higher average E/e' (median [interquartile range]:16.04 [13.1 to 22.46] vs. 14.1 [10.89 to 19]; p = 0.036) and worse longitudinal left atrial strain peak positive value (16.86 ± 12.15% vs. 23.67 ± 14.09%; p = 0.002) compared to PMR. During follow-up (median: 22 months), patients with AFMR had worse survival (log-rank p = 0.009) and more heart failure hospitalizations (log-rank p = 0.002). They were also less likely to undergo mitral valve intervention (59.0% vs. 83.6%; p = 0.001), although surgery was associated with improved survival (log-rank p = 0.021). On multivariable regression analysis, AFMR was independently associated with mortality [adjusted odds ratio: 2.61, 95% confidence interval: 1.17 to 5.83; p = 0.02].

Conclusions: AFMR constitutes an under-recognized high-risk group, with significant comorbidities, limited therapeutic options, and poor outcomes.