Open-Label, Multicenter Study of Flecainide Acetate Oral Inhalation Solution for Acute Conversion of Recent-Onset, Symptomatic Atrial Fibrillation to Sinus Rhythm

BACKGROUND: Oral and intravenous flecainide is recommended for cardioversion of atrial fibrillation. In this open-label, dose-escalation study, the feasibility of delivering flecainide via oral inhalation (flecainide acetate inhalation solution) for acute conversion was evaluated. We hypothesized that flecainide delivered by oral inhalation would quickly reach plasma concentrations sufficient to restore sinus rhythm in patients with recent-onset atrial fibrillation. METHODS: Patients (n=101) with symptomatic atrial fibrillation (for ≤48 hours) self administered flecainide acetate inhalation solution using a nebulizer (30 mg [n=10], 60 mg [n=22], 90 mg [n=21], 120 mg [n=19], and 120 mg in a formulation containing saccharin [n=29]). Electrocardiograms and flecainide plasma concentrations were obtained, cardiac rhythm using 4-hour Holter was monitored, and adverse events were recorded. RESULTS: Conversion rates increased with dose and with the maximum plasma concentrations of flecainide. At the highest dose, 48% of patients converted to sinus rhythm within 90 minutes from the start of inhalation. Among patients who achieved a maximum plasma concentration >200 ng/mL, the conversion rate within 90 minutes was 50%; for those who achieved a maximum plasma concentration