Efficacy of low-dose amiodarone in the prevention of paroxysmal atrial fibrillation resistant to type IA antiarrhythmic drugs.

The efficacy and safety of low-dose amiodarone (Cordarone; Wyeth-Ayerst, Philadelphia, PA) was assessed in 62 symptomatic patients with paroxysmal atrial fibrillation who were resistant to at least two types of IA drugs. The beneficial response to this treatment was defined as a reduction in paroxysmal atrial fibrillation of greater than or equal to 50% within 1 month. Of the 42 patients (67.7%) who were responders, 39 (62.9%) were completely free of episodes. Intolerable side effects were seen in 12 patients (19.3%). Tolerable side effects were encountered by 73% of patients. Most of the adverse effects were transient and responded to a reduction in the dose. In conclusion, (1) low-dose amiodarone produces a beneficial response in the prevention of paroxysmal atrial fibrillation, and (2) low-dose amiodarone is well tolerated.