NEW YORK (Reuters Health) – The novel antiarrhythmic agent vernakalant is a safe and effective agent for pharmacologic conversion of recent-onset atrial fibrillation (AF) in hemodynamically stable patients, investigators report.
By blocking early activating potassium and sodium channels, vernakalant selectively prolongs atrial refractoriness and slows atrial conduction, without affecting ventricular refractoriness, the researchers explain in the American Heart Journal for June.
The multinational, open-label study, headed by Dr. Ian G. Stiell at the University of Ottawa, included 236 adult patients with AF lasting more than 3 hours. Treatment involved a 10-minute IV infusion of vernakalant 3 mg/kg, followed by a second infusion (2 mg/kg) 15 minutes later if AF had not been achieved.
Among the 167 subjects whose AF had begun no more than 7 days previously, 50.9% converted to sinus rhythm within 90 minutes after starting treatment. However, only 11.6% of 69 patients with longer duration AF (8 to 45 days) were converted. All but two of the 93 responders with available data were still in sinus rhythm at 24 hours.
The authors report that five patients developed serious bradycardia, which lasted less than 20 minutes in four; all five recovered without sequelae. Severe hypotension within the first 24 hours occurred in four patients.
Twelve patients developed ventricular arrhythmia within 2 hours of the vernakalant infusion, including nonsustained monomorphic ventricular tachycardia in five.
The one death that occurred during 30-day follow-up was not related to treatment.
The most common non-serious adverse events — dysgeusia, sneezing, and paresthesia — resolved spontaneously. There were no episodes of torsades de pointes, ventricular fibrillation, or sustained ventricular tachycardia.