[Comparison of amiodarone and quinidine in the conversion to sinusal rhythm of atrial fibrillation of recent onset].

The effectiveness of amiodarone and quinidine in converting atrial fibrillation of recent onset (less than three weeks) to sinus rhythm was compared in a randomized, open-label study. Patients with signs of heart failure determining a NYHA class 3 or 4, acute myocardial infarction, unstable angina pectoris, sick sinus syndrome, Wolff-Parkinson-White syndrome, conduction disturbances, dysthyroidism, or undergoing concomitant therapy with antiarrhythmic drugs, were excluded from the study. Sixty-eight consecutive patients were randomized to receive amiodarone (group A) or quinidine (group B). Group A was treated with amiodarone intravenously as a bolus of 5 mg/Kg over a 20 min period followed by a 15 mg/Kg infusion during the first 24 hours and then orally at a dose of 0.4 g every 6 hours. Group B was treated with quinidine sulphate orally at a dose of 0.2 g every 6 hours during the first day; 0.4 g every 6 hours the second day and 0.6 g every 6 hours during the third day of therapy. Quinidine was preceded by rapid intravenous digitalization depending on the patient's clinical status so as to obtain a ventricular rate of about 100 beats/min, with subsequent oral digitalis administration in maintenance doses. Both treatments were continued until conversion or for a maximum of three days. If the sinus rhythm was not restored, patients underwent electrical cardioversion. Drug efficacy was assessed on the basis of conversion to sinus rhythm. Six patients converted to sinus rhythm with intravenous digitalization alone and were excluded from the comparison between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)