EFFECTS OF AMIODARONE VERSUS QUINIDINE AND VERAPAMIL IN PATIENTS WITHCHRONIC ATRIAL-FIBRILLATION - RESULTS OF A COMPARATIVE-STUDY AND A 2-YEAR FOLLOW-UP

Rapid, reliable and safe reestablishment of sinus rhythm is the major aim of pharmacologic treatment in patients with chronic atrial fibrill ation. The mainstay of therapy in this arrhythmia has been quinidine. More recently, amiodarone was shown in non-comparative studies to be s uperior to class IA agents under certain conditions. In 40 patients wi th atrial fibrillation persisting for 4 weeks up to 2 years, the effic acy and safety of either quinidine an verapamil (days 1 to 3, quinidin e 1,500 mg/day; days 4 to 6, quinidine 1,500 mg + verapamil 240 mg/day ) or amiodarone therapy (days 1 to 3, amiodarone 1,200 mg/day intraven ously; days 4 to 14, amiodarone 800 mg/day orally) were randomly exami ned. Responders continued on their effective medication for 3 months. Thereafter, all patients were treated with a fixed regimen of quinidin e (480 mg/day) plus verapamil (240 mg/day) for up to 2 years. During a trial fibrillation, quinidine reduced mean ventricular cycle length by 40 ms (-5%), quinidine and verapamil increased mean cycle length by 5 7 ms (8%) and amiodarone by 192 ms (28%, p < 0.01). In addition, quini dine and verapamil had a characteristic "rate-smoothing" effect on atr ioventricular conduction during atrial fibrillation. The rhythm was co nverted to sinus rhythm after quindine in 5 (25%) of 20 patients and a fter the combination of quinidine and verapamil in 11 (55%) of 20 pati ents. Amiodarone restored sinus rhythm in 12 (60%) of 20 patients. Ove rall, a shorter duration of atrial fibrillation (p < 0.05) and a small er left atrial size (p < 0.01) were predictive of successful conversio n of the arrhythmia. In one patient on each regimen, medication was st opped because of side effects. Transient side effects occurred in 13 p atients (33%), 5 receiving quinidine and verapamil and 8 receiving ami odarone. During long-term treatment, amiodarone could be safely replac ed by quinidine and verapamil. Among 23 drug responders, atrial fibril lation recurred in 2 (1st 3 months), 5 (1st year) and 7 patients (2 ye ars); side effects limited long-term therapy in 2 patients. In summary , a similar efficacy rate of 50% to 60% to reestablish sinus rhythm fa vors the clinical situation (e.g., left ventricular function, fast ven tricular rate) to select the drug of choice for a particular patient. When sinus rhythm is reestablished, quinidine and verapamil provide a safe and effective therapeutic regimen in 60% of patients over a 2-yea r follow-up period.