Metoprolol vs diltiazem for atrial fibrillation with rapid ventricular rate: Systematic review and meta-analysis of adverse events.

Background: Intravenous (IV) diltiazem and metoprolol are commonly used to achieve rate control for atrial fibrillation with RVR (Afib with RVR), and are both recommended as first-line by current guidelines. While prior studies investigated the efficacy of these medications, there is little evidence available regarding the risk of adverse events (AEs) with their use.

Methods: We identified randomized controlled trials (RCT) and observational studies reporting rates of AEs following administration of IV diltiazem and metoprolol for Afib with RVR by searching PubMed, SCOPUS, EMBASE, and Cochrane Library. Our primary outcome was the incidence of AEs and specifically hypotension and bradycardia, which were examined individually as secondary outcomes. We performed random-effects meta-analysis to identify rates of each AE. We used moderator analysis and meta-regressions to evaluate risk factors. We used the Cochrane Risk-of-Bias 2 tool and the Newcastle-Ottawa Scale to assess study quality.

Results: We reviewed 13 studies and included 1660 patients, 888 (53 %) treated with metoprolol and 772 (47 %) with diltiazem. Metoprolol was associated with a 26 % lower risk of AE (total incidence 10 %) compared to diltiazem (total incidence 19 %), (RR 0.74, 95 % CI 0.56-0.98, p = 0.034) with a prediction interval of 0.50-1.10. Patients with higher initial heart rates faced higher rates of AEs (Correlation Coefficient 0.11, 95 % CI 0.03-0.19, p = 0.006). There was no difference with respect to rates of bradycardia (RR 0.44, 95 % CI 0.15-1.30, p = 0.14) or hypotension (RR 0.80, 95 % CI 0.61-1.04, p = 0.10).

Conclusion: Afib with RVR treated with metoprolol had lower rates of AE (bradycardia and/or hypotension) compared to those treated with diltiazem. We found no difference in rates of hypotension or bradycardia when individually assessed. Existing data are limited by small sample sizes, variability in dosing, and limited representation of important patient subgroups.