Safety, Side Effects and Relative Efficacy of Medications for Rhythm Control of Atrial Fibrillation in Hypertrophic Cardiomyopathy

In patients with hypertrophic cardiomyopathy (HC), atrial fibrillation (AF)is common, often poorly tolerated and difficult to treat. Limited data exists regarding safety or efficacy of drug therapy for AF rhythm control in HC patients. We performed a retrospective analysis of patients with HC followed >6 months, treated with amiodarone, sotalol, dofetilide, or disopyramide for rhythm control of non-postoperative AF. The duration followed on each medication, reasons for discontinuing, and incidences of adverse events were recorded. Confounding factors including maximum ventricular septal thickness, age, left ventricular ejection fraction, and gender were assessed. Ninety-eight patients had 130 drug treatments (defined as a continuous time on 1 drug); 23 patients were treated with >1 medication. The probability of remaining on a single antiarrhythmic drug at 1 year was 62% and at 3 was 42%. Maximum ventricular septal thickness (hazard ratio 1.05, p = 0.03)and presence of resting outflow gradient (hazard ratio 2.50, p = 0.002)were associated with discontinuation of therapy. Patients treated with amiodarone or sotalol had no serious safety events suggesting that these medications may be reasonably safe. Amiodarone was least likely to be discontinued for inefficacy (8.5%), but likely to be discontinued for side effects (19%). The probability of remaining on sotalol was 74% at 1 year and 50.0% at 3 and it was only discontinued for side effects in 2%. A small number of patients were treated with disopyramide and dofetilide. In conclusion, our data suggest that amiodarone and sotalol are likely safe, and that sotalol may be particularly attractive given its low rate of side effects and low rate of discontinuation.