LONG-TERM EFFICACY OF AMIODARONE FOR THE MAINTENANCE OF NORMAL SINUS RHYTHM IN PATIENTS WITH REFRACTORY ATRIAL-FIBRILLATION OF FLUTTER

The purpose of this study was to examine the efficacy and safety of am iodarone to maintain sinus rhythm in patients with refractory atrial f ibrillation or flutter. One hundred ten patients with atrial fibrillat ion or flutter, refractory to greater than or equal to 1 class I antia rrhythmic agents (mean +/- SD 2.5 +/- 1.5, median 2), were given low-d ose amiodarone (mean maintenance dose 268 +/- 100 mg/day) to determine its efficacy to maintain normal sinus rhythm after chemical or electr ical cardioversion. Fifty-three patients had chronic and 57 patients h ad paroxysmal atrial fibrillation or flutter. Mean age of the study po pulation was 60 +/- 13 years, and the mean follow-up was 36 +/- 38 mon ths (range 31 days to 137 months). Actuarial rates for maintenance of sinus rhythm were 0.87, 0.70, and 0.55 at 1, 3, and 5 years, respectiv ely. Twenty-one patients (19%) with arrhythmia recurrence had an incre ase in amiodarone dose, and after a mean additional follow-up of 2.5 y ears, 86% remained in normal sinus rhythm. The only observed predictor of atrial fibrillation or flutter recurrence was paroxysmal arrhythmi a (40% recurrence vs 9% in patients with chronic atrial fibrillation o r flutter; p<0.001). Actuarial rates for withdrawal because of adverse effects were 0.08, 0.22, and 0.30 at 1, 3, and 5 years, respectively. The most frequent adverse effects necessitating withdrawal were skin discoloration (4.5%), pulmonary fibrosis (3.6%; none fatal), and thyro id toxicity (2.7%). No deaths occurred during the study period. In con clusion, amiodarone has a high degree of efficacy for maintaining norm al sinus rhythm in patients with atrial fibrillation or flutter, with a relatively low incidence of adverse effects necessitating withdrawal .