Intravenous vernakalant in comparison with intravenous flecainide in the cardioversion of recent-onset atrial fibrillation

Background:: Pharmacological cardioversion of atrial fibrillation is a reasonable alternative for electrical cardioversion in acute atrial fibrillation. We compared the efficacy and safety of intravenous vernakalant and intravenous flecainide in patients with recent-onset (< 48 h) atrial fibrillation.

Methods:: A total of 200 consecutive patients, 100 patients undergoing cardioversion with intravenous vernakalant and 100 patients undergoing cardioversion with intravenous flecainide, were included in this single centre non-randomized retrospective study. The primary endpoint was conversion to sinus rhythm within 120 minutes from the drug administration.

Results:: Cardioversion was successful in 67% of patients treated with vernakalant and in 46% of patients treated with flecainide ( p=0.003). Vernakalant (odds ratio 1.99, 95% confidence interval 1.08-3.69, p=0.029) and female gender (odds ratio 2.48, 95% confidence interval 1.22-15.05, p=0.012) were significant predictors of successful cardioversion. The success rate of cardioversion was lowest among men treated with flecainide (36.9%). Patients treated with vernakalant were discharged earlier from the emergency department compared with those treated with flecainide (8.2 ± 4.7 h vs. 12.0 ± 6.0 h, p < 0.001). There was no difference in the complication rate between the groups. Vernakalant treated patients were older (59.3 ± 12.5 vs. 55.4 ± 13.0 years, p=0.03), had higher CHA₂DS₂-VASc score (1.4 ± 1.3 vs. 0.9 ± 1.2, p = 0.002) and were more often on beta-blocker medication (59% vs. 42%, p= 0.016) than flecainide treated patients.

Conclusion:: Vernakalant was safe, more effective and faster than flecainide in the cardioversion of recent-onset atrial fibrillation. The difference in efficacy was especially apparent among men.