Maintenance of sinus rhythm with metoprolol CR initiated before cardioversion and repeated cardioversion of atrial fibrillation: a randomized double-blind placebo-controlled study.

AIMS: To assess the effect of metoprolol in combination with repeated cardioversion on maintenance of sinus rhythm (SR). METHODS AND RESULTS: Consecutive outpatients with persistent atrial fibrillation (AF) were randomized to treatment with metoprolol CR or placebo in a double-blind fashion. Study treatment was started at least one week before direct current (DC) cardioversion. Patients were followed once a week during the first 6 weeks after cardioversion. In case of relapse during this period, a second cardioversion was performed. Total treatment time was 6 months. A total of 168 patients were randomized to metoprolol (n = 83) or placebo (n = 85). The dose of study treatment at cardioversion was 169 +/- 47 mg in the metoprolol group and 180 +/- 40 mg in the placebo group (P = 0.12). In an intention-to-treat analysis, 46 patients (55%) in the metoprolol group and 34 patients (40%) in the placebo group (P = 0.04) had SR 1 week after cardioversion, and 38 patients (46%) in the metoprolol group compared with 22 patients (26%) in the placebo group had SR after 6 months (P < 0.01). CONCLUSION: A treatment strategy of metoprolol CR started before cardioversion in combination with prompt second cardioversion in case of early relapse (1-6 weeks) significantly increases the proportion of patients in SR during six months of follow-up.