Utility of adjunctive single oral bolus propafenone therapy in patients with atrial defibrillators

Aims Previous studies have demonstrated that ambulatory atrial defibrillation shocks delivered by an implantable cardioverter-defibrillator (ICD) are safe and effective, but poorly tolerated. Separate studies have demonstrated the utility of single oral bolus propafenone for conversion of recent-onset atrial fibrillation (AF); however, most patients were hospitalized, had no structural heart disease, were taking no other antiarrhythmic drugs, and were not exposed to concomitant shock. We hypothesized that a single oral bolus dose of propafenone given early after onset would be a safe and effective adjunct to ICD-based AF therapy and improve overall therapy tolerance. Methods and results A randomized three-way crossover study design was used to compare three strategies, deployed in the ambulatory setting early after AF episode onset in 35 ICD patients with advanced, drug refractory episodic/persistent syndromes, many of whom had structural heart disease and were taking other antiarrhythmic drugs: (i) single oral bolus propafenone (600 mg), followed by ICD shock if necessary; (ii) single oral bolus placebo, followed by ICD shock if necessary; and (iii) no oral bolus therapy and ICD shock if necessary (no bolus). Antiarrhythmic efficacy, defined by the restoration of sinus rhythm within 24 h, was similar during propafenone (81%) and no-bolus strategies (84%); both were significantly higher than during placebo strategy (62%). Propafenone was well tolerated and not associated with proarrhythmia. Shock use was significantly tower during propafenone strategy (19%) than during no-bolus strategy (55%); this was correlated with improved patient tolerance. Conclusion Adjunctive use of single oral bolus propafenone is safe and effective in patients with an ICD and improves patient tolerance of device-based AF therapy.