Oral amiodarone increases the efficacy of direct-current cardioversion in restoration of sinus rhythm in patients with chronic atrial fibrillation

Aims Direct current cardioversion of persistent atrial fibrillation is one of the most widely used and effective treatments for the restoration of sinus rhythm, but may be hampered by a low success rate and a high percentage of early recurrence. pre-treatment with amiodarone or a glucose-insulin-potassium solution could improve the efficacy of electrical cardioversion by reversing the partially depolarized diastolic potential of the subsidiary pacemakers in atrial fibrillation. In a controlled randomized study, we assessed the effectiveness of electrical cardioversion in patients with persistent atrial fibrillation after pre-treatment with amiodarone or potassium infusion and the efficacy of amiodarone in maintaining sinus rhythm after electrical cardioversion. Methods and Results Ninety-two patients with persistent atrial fibrillation (>2 weeks duration) were prospectively randomized into three matched groups: A (n=31, oral amiodarone 400 mg. day(-1) 1 month before and 200 mg.day(-1) 2 months after cardioversion), B (n=31, 180 mg.day(-1) oral diltiazem 1 month before and 2 months after cardioversion and 80 mmol potassium, 50 UI insulin in 500 mi 30%;, glucose solution 24 h before cardioversion) and C (n=30, control patients, 180 mg. day(-1) oral diltiazem 1 month before and 2 months after cardioversion). Before cardioversion all patients were under 4 weeks effective oral anticoagulant therapy (warfarin). Before electrical cardioversion, the rate of spontaneous conversion to sinus rhythm was higher in group A (25%) than groups B (6%) or C (3%) (P<0.005). Electrical cardioversion was more successful in group A (88%) than groups B (56%) or C (65%) (P<0.05), while the electrical thresholds for effective cardioversion were lower in group B than the other groups (P<0.05). Twenty-four hours after cardioversion, the early recurrence of atrial fibrillation was similar in the three groups (P=ns), while at 2 months the recurrence rate was lower in group A (32%) than groups B (56%) or C (52%) (P<0.01). Conclusion Pre-treatment with low-dose oral amiodarone, compared with oral diltiazem or glucose-insulin-potassium treatments, induces a significantly high percentage of instances of spontaneous conversion, increases electrical cardioversion efficacy and reduces atrial fibrillation recurrence. (Eur Heart J 2000; 21: 66-73) (C) 2000 The European Society of Cardiology.