A CONTROLLED-STUDY ON ORAL PROPAFENONE VERSUS DIGOXIN PLUS QUINIDINE IN CONVERTING RECENT-ONSET ATRIAL-FIBRILLATION TO SINUS RHYTHM

Eighty-seven patients with recent onset atrial fibrillation (less-than -or-equal-to 8 days) without clinical signs of heart failure were rand omly allocated to one of the following treatments: (i) oral propafenon e (600 mg as a loading dose followed after 8 h by 300 mg t.i.d.); (ii) intravenous digoxin as acute scheme (up to 1.125 mg/24 h) followed af ter 6 h by hydroquinidine chlorhydrate (total dose, 1350 mg); or (iii) placebo. The patients were submitted to Holter monitoring for 48 h. R esults: propafenone achieved higher successful conversion rates at 6, 12 and 24 h compared either with placebo (62% vs. 17%, 83% vs. 34%; 86 % vs. 55%; P < 0.01, respectively) or with digoxin at 6 h (62% vs. 38% ; P < 0.05) and digoxin plus quinidine at 12 h (83% vs. 48%; P < 0.05) . At 48 h, a placebo conversion rate of 76% was observed with conseque nt lack of any significant difference with the active treatments. Mean conversion times within 48 h were 267 +/- 238 min for propafenone, 64 8 +/- 631 min for digoxin plus quinidine (P < 0.01 vs. propafenone) an d 893 +/- 622 min for placebo (P < 0.001 vs. propafenone). Propafenone and digoxin plasma levels were within the therapeutic range. Asymptom atic phases of atrial flutter with greater-than-or-equal-to 2:1 atrio- ventricular conduction ratio were observed during Holter monitoring, b efore conversion to sinus rhythm, in four patients treated with propaf enone, in one patient taking digoxin plus quinidine and in four patien ts with placebo. One patient experienced syncope while standing up, 8 h after the beginning of propafenone treatment, due to a 1:1 atrial fl utter with aberrant ventricular conduction. In conclusion, propafenone as an oral loading dose followed by oral treatment is highly and quic kly effective in converting recent onset atrial fibrillation to sinus rhythm compared with placebo. Digoxin and digoxin plus quinidine, at t he doses employed, had a lower success rate and more prolonged convers ion times. The high rate of conversion to sinus rhythm during placebo underlines the need for controlled studies in this subset of patients.