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Evidence summaries

Metoprolol for Maintaining Sinus Rhythm after Cardioversion of Atrial Fibrillation

Metoprolol appears to be better than placebo in maintaining sinus rhythm after cardioversion of atrial fibrillation. Level of evidence: "B"

The quality of evidence is downgraded by inconsistency (unexplained variabiliy in results).

Summary

A Cochrane review on antiarrhythmics for maintaining sinus rhythm after cardioversion of atrial fibrillation[Abstract] 1 included 59 studies with a total of 20 981 subjects. Metoprolol was included in 3 of the studies (n=697), and 2 of them compared metoprolol with placebo.

Metoprolol seemed to reduce recurrence of atrial fibrillation compared with placebo, but the difference was not statistically significant (RR 0.83, 95% CI 0.68 to 1.02; 2 studies, n=562; statistical heterogeneity I2 =59%). Recurrence rates were 72.0% in people receiving placebo and 59.7% (49.0% to 73.4%) in people receiving metoprolol.

Metoprolol increased proarrhythmia compared to placebo due mainly to symptomatic bradyarrhythmias (94% of all proarrhythmic events; RR 18.14, 95% CI 2.42 to 135.66; 2 studies, n=562). Proarrhythmic events were reported in no participants in the placebo group and in 60 participants per 1000 people in the metoprolol group; NNTH was 19 (95% CI 2 to 235) participants treated for 1 year to have one additional bradyarrhythmia.The risk of withdrawing due to adverse events was more than 3 times higher among people receiving metoprolol than people receiving placebo (RR 3.47, 95% CI 1.48 to 8.15; 2 studies, n=562). This represented 21 per 1000 people receiving placebo withdrawing compared with 74 (95% CI 31 to 173) per 1000 people receiving metoprolol; NNTH was 19 (95% CI 7 to 99). Metoprolol showed no significant difference in mortality (RR 2.02, 95% CI 0.37 to 11.05; 2 studies, n=562) compared to placebo.

    References

    • Valembois L, Audureau E, Takeda A et al. Antiarrhythmics for maintaining sinus rhythm after cardioversion of atrial fibrillation. Cochrane Database Syst Rev 2019;(9):CD005049. [PubMed]

Primary/Secondary Keywords