AMIODARON AND VERAPAMIL CHINIDIN IN THE T REATMENT OF PATIENTS WITH CHRONIC ATRIAL-FIBRILLATION

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 noncomparative studies to be su perior to class IA agents under certain conditions. In 40 patients wit h atrial fibrillation persisting for 4 weeks up to 2 years, the effica cy and safety of either quinidine and 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 quinidine (480 mg/day) plus verapamil (240 mg/day) for up to 2 years. During at rial fibrillation, quinidine reduced mean ventricular cycle length by 40 ms (-5%), quinidine and verapamil increased mean cycle length by 57 ms (8%) and amiodarone by 192 ms (28%, p < 0.01). In addition, quinid ine and verapamil had a characteristic ''rate-smoothing'' effect on at rioventricular conduction during atrial fibrillation. The rhythm was c onverted to sinus rhythm after quinidine in 5 (25%) of 20 patients and after the combination of quinidine and verapamil in 11 (55%) of 20 pa tients. Amiodarone restored sinus rhythm in 12 (60%) of 20 patients. O verall, a shorter duration of atrial fibrillation (p < 0.05) and a sma ller left atrial size (p < 0.01) were predictive of successful convers ion of the arrhythmia. In one patient on each regimen, medication was stopped because of side effects. Transient side effects occurred in 13 patients (33%), 5 receiving quinidine and verapamil and 8 receiving a miodarone. During long-term treatment, amiodarone could be safely repl aced by quinidine and verapamil. Among 23 drug responders, atrial fibr illation reoccurred in 2 (1st 3 months), 5 (1st year) and 7 patients ( 2 years); side effects limited long-term therapy in 2 patients. In sum mary, a similar efficacy rate of 50% to 60% to reestablish sinus rhyth m favors the clinical situation (e.g., left ventricular function, fast ventricular rate) to select the drug of choice for a particular patie nt. When sinus rhythm is reestablished, quinidine and verapamil provid e a safe and effective therapeutic regimen in 60% of patients over a 2 -year followup period.