Low-dose amiodarone for maintenance of sinus rhythm after cardioversion of atrial fibrillation or flutter.

OBJECTIVE--To study efficacy and safety of low-dose amiodarone for maintenance of sinus rhythm after electrical cardioversion of atrial fibrillation or flutter. DESIGN--Nonrandomized trial; mean duration of follow-up, 20.7 months. SETTING--Referral center; institutional practice; both hospitalized and ambulatory care. PATIENTS--Eighty-nine consecutive patients having chronic atrial fibrillation or flutter and eligible for cardioversion. Patients had failed previous treatment aimed at maintaining sinus rhythm. During follow-up one patient was withdrawn because of side effects; all patients were available for follow-up. INTERVENTION--Before cardioversion, patients received 600 mg of amiodarone daily during a 4-week loading period. After conversion, the daily maintenance dose was 204 +/- 66 mg (mean +/- SD). MAIN OUTCOME MEASURES--Arrhythmia recurrence and adverse effects causing drug discontinuation. RESULTS--During loading, 15 patients (16%) converted, and after electrical cardioconversion, 90% of all patients had sinus rhythm. Actuarially, 53% of these patients were still in sinus rhythm after 3 years. In patients with compromised left ventricular function, 93% maintained sinus rhythm after 6 months. One patient died due to congestive heart failure. Intolerable side effects occurred in one patient. No proarrhythmia was observed. Logistic regression analysis revealed that amiodarone was ineffective in patients with mitral stenosis or chronic arrhythmia. CONCLUSIONS--Low-dose amiodarone is effective for maintaining sinus rhythm in patients with difficult to treat chronic atrial fibrillation or flutter and is associated with a low incidence of serious side effects.