Atrial fibrillation and high-grade functional mitral regurgitation - what is the chicken, what is the egg?

Abstract Background Atrial fibrillation (AF) and mitral valve regurgitation (MR) represent highly prevalent and intimately linked comorbidities with shared and interacting pathophysiological mechanisms [1]. The first-time and simultaneous occurrence of high-grade functional MR (fMR) and AF therefore often poses a chicken-or-egg dilemma, rendering clinical decision making on which of the two conditions should prioritized challenging. To date, data regarding the rationale and the timing of MR therapy in this cohort are lacking. Purpose The aim of the present study was to identify predictors of persistence of de novo high-grade fMR after rhythm control of concomitant de novo AF in order to provide guidance for the early clinical management of this relevant cohort of patients. Methods In a single center observational cohort study, consecutive patients presenting with first diagnosed MR and AF undergoing acute rhythm control of AF were identified and patients with non-high-grade MR, primary MR, simultaneous cardiogenic shock, prior mitral valve repair or replacement, endocarditis, intracardiac thrombi and/or concomitant relevant pathology of the aortic valve were excluded. Clinical and echocardiographic parameters at baseline and follow-up (FU) were assessed and predictors of persistence of high-grade fMR at FU were identified via multivariable logistic regression analyses. Results A total of 780 consecutive patients were identified between 2016 and 2022, of whom 100 patients were enrolled in the study. Acute rhythm control of AF was achieved predominantly by electrocardioversion (90%, 90/100) and in a minority by pulmonary vein isolation (10%, 10/100). After a median FU period of 318 days (IQR 849 days), 59% (59/100) patients showed mild to moderate fMR and 41% (41/100) patients presented with persisting high-grade fMR, of whom 44% (18/41) and 39% (16/41) underwent surgical or percutaneous MR therapy, respectively. The remaining 17% (7/41) were conservatively treated. AF/AT recurrence was not associated with persistent high-grade MR (Odds ratio [OR] 2.4, 95% confidence interval [CI] 0.6-4.5, p = 0.2), whereas concomitant first degree AV block (OR 1.4, 95%-CI 1.1-1.7, p=0.005), pulmonary hypertension (OR 1.3, 95%-CI 1.1-1.6, p=0.004) and NYHA functional class IV (OR 1.4, 95%-CI 1.1-1.6, p=0.02) at the time of first presentation were found to be predictors of persistent high-grade MR during FU in multivariable logistic regression. Conclusion Patients with de novo high-grade MR and AF presenting with concomitant first degree AV block, NYHA functional class IV or pulmonary hypertension are more likely to have persistent high-grade MR after early rhythm control of AF regardless of sinus rhythm stability during FU. In this constellation, early definitive therapy for MR should be prioritized. Larger, prospective studies are needed to confirm the results and to investigate the impact of early interventional rhythm control strategies on MR reversibility.