[Long-term preventive effect and safety of amiodarone in patients with paroxysmal atrial fibrillation refractory to class I antiarrhythmic agents: analysis based on patient profiles].

OBJECTIVES AND METHODS: The factors controlling the preventive effect of long-term amiodarone therapy were evaluated in patients with paroxysmal atrial fibrillation. The 55 patients (37 men and 18 women, mean age 68 +/- 9 years) with paroxysmal atrial fibrillation refractory to more than two types of Class I antiarrhythmic agents received amiodarone (100-200mg/day) after electrical or pharmacological cardioversion. All patients were observed for 12 months or more (mean follow-up period 48.6 +/- 29.1 months).

RESULTS: Actuarial recurrence-free rate at 12 months in patients with ejection fraction < 55% (76.5%, n = 17) was significantly higher than that in patients with ejection fraction > or = 55% (44.7%, n = 38) (p = 0.0411), and tended to be higher in patients with underlying heart disease (65.5%, n = 29) than in patients without underlying heart disease (42.3%, n = 26) (p = 0.0980). Age, sex, diabetes mellitus, alcohol intake, hypertension, hyperlipidemia, and administration of angiotensin converting enzyme inhibitor were not related to the effect of amiodarone. Relative risk reduction of recurrence after amiodarone therapy was 4.01 (95% confidence interval 3.57-4.45) in patients with ejection fraction < 55%, and 2.59 (95% confidence interval 2.07-3.11) in patients with underlying heart disease. None of the above-mentioned factors was related to the development of adverse effects. The incidence of adverse effects requiring discontinuation in all patients was 7.3%.

CONCLUSIONS: Amiodarone was more effective for preventing recurrence in patients with poorer left ventricular function and underlying heart disease.