Impact of Beta-Blockade on Cardiac Events in Patients with Chronic Severe Nonischemic Mitral Regurgitation
Objectives: The aim of this study was to examine the impact of beta-blockade on cardiac events among patients with initially asymptomatic chronic severe nonischemic mitral valve regurgitation (MR). Methods: Data from 52 consecutive patients in our prospective natural history study of isolated chronic severe nonischemic MR were assessed post hoc over 19 years to examine the relation of chronic beta-blockade use to subsequent cardiac events (death or indications for mitral valve surgery, MVS). At entry, all patients were free of surgical indications; 9 received beta-blockers. Cardiac event rate differences were analyzed by Kaplan-Meier log rank comparison. Results: During follow-up, cardiac events included sudden death (1), heart failure (8), atrial fibrillation (6), left ventricular dimensions at systole ≥4.5 cm (11), left ventricular ejection fraction <60% (6), right ventricular ejection fraction <35% (2), and a combination of cardiac events (7). The cardiac event risk was 4-fold higher among patients receiving beta-blockers (average annual risk = 60.6%) versus those not receiving beta-blockers (average annual risk = 15.2%; p = 0.001). These effects remained statistically significant (p = 0.005) when analysis was adjusted for other baseline covariates. Conclusions: Beta-blockade appears to confer an increased risk of sudden cardiac death or indications for MVS among patients with chronic severe nonischemic MR. Randomized trials are needed to confirm these findings.