Azimilide for the treatment of atrial fibrillation, atrial flutter, and paroxysmal supraventricular tachycardia: results of a randomized trial and insights on the concordance of symptoms and recurrent arrhythmias.

INTRODUCTION Azimilide hydrochloride is an investigational antiarrhythmic medication that had shown evidence of efficacy in prolonging the time to recurrence of atrial fibrillation (AF) or atrial flutter (AFL) and paroxysmal supraventricular tachycardia (PSVT). This study was designed to confirm efficacy of 125 mg daily azimilide. METHODS AND RESULTS The primary endpoint was ECG-documented recurrence of AF, AFL, or PSVT, followed for a maximum of 180 days. Four hundred eighty-two patients were enrolled in the United States and Canada (422 with AF or AFL and 60 with PSVT). The primary efficacy analysis included 402 patients with AF-AFL and 56 patients with PSVT. There was no significant difference in the time to first recurrence of symptomatic supraventricular arrhythmia in the AF-AFL stratum (median of 38 days for azimilide versus 27 days for placebo; hazard ratio [HR] of 1.14, P = 0.29). Similarly, there was no difference in time to recurrence in the PSVT stratum (>180 days for azimilide versus 135 days for placebo; HR = 1.28, P = 0.55). There were three deaths in the azimilide group and one in the placebo group. Four patients had nonsustained ventricular tachycardia (one torsades de pointes), all in the azimilide group. Asymptomatic recurrence was frequent in the AF-AFL group (8% with azimilide and 11% with placebo), but was absent in the PSVT group. False recurrence was common in both groups. CONCLUSION Azimilide 125 mg daily was not associated with significant prolongation of the time to recurrent symptomatic supraventricular arrhythmias. There was substantial discordance between symptoms and recurrence.