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A Randomized Placebo-Controlled Study of Vernakalant (Oral) for the Prevention of Atrial Fibrillation Recurrence Post-Cardioversion
Study Questions:
How effective is vernakalant for preventing recurrent atrial fibrillation (AF) after direct-current cardioversion?
Methods:
The subjects of this study were 732 patients (mean age 63 years) referred for cardioversion of AF 3 days to 6 months in duration. The patients were randomly assigned to receive placebo or vernakalant at a dosage of 150, 300, or 500 mg twice daily. Cardioversion was performed after 3 days of treatment. Recurrent AF during 90 days of follow-up was detected by serial clinic visits and daily transtelephonic monitor recordings.
Results:
The proportion of patients still in sinus rhythm at 90 days of follow-up was significantly higher in the vernakalant 500 mg twice-daily group (53%) than in the placebo group (39%, odds ratio 0.74). The other dosages of vernakalant did not significantly reduce the incidence of recurrent AF. The incidence of significant adverse events was similar in each of the four study arms. The most frequent drug-related adverse event was bradycardia, which occurred in 2.7% of patients in the 500 mg group compared to 1.1% in the other groups. There were no instances of ventricular proarrhythmia.
Conclusions:
The authors concluded that vernakalant at a dose of 500 mg twice daily is safe and reduces the odds of recurrent AF after cardioversion by 26%.
Perspective:
Vernakalant is a multiple ion channel blocker that targets potassium channels specific to the atria and also blocks sodium channels in a rate-dependent fashion. Because it has little or no effect on potassium channels in the ventricle, it appears to be free of the risk of ventricular proarrhythmia, a major advantage over currently available potassium channel blockers such as sotalol or dofetilide.
Keywords: Follow-Up Studies, Potassium Channel Blockers, Pyrrolidines, Phenethylamines, Sulfonamides
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