Value of single oral loading dose of propafenone in converting recent-onset atrial fibrillation. Results of a randomized, double-blind, controlled study.

Aims: To evaluate the efficacy and safety of a single loading oral dose of propafenone in the interruption of recent-onset atrial fibrillation.

Methods: After a complete medical history, physical examination, 12-lead ECG, chest X-ray, and routine biochemical laboratory testing, 55 consecutive patients with recent-onset atrial fibrillation were randomized double-blind in the emergency department for the administration of either a single oral dose (450 to 750 mg) of propafenone (29 cases) or a placebo (26 cases). After the 24-h observation period, comprehensive echocardiographic examination was performed.

Results: The groups were homogeneous as regards biological, clinical and echocardiographic characteristics. Two hours after treatment, 12 patients (41%) on propafenone but only two (8%) on placebo had converted to sinus rhythm (P = 0.005). This striking difference was maintained 6 h after treatment (65 vs 31%; P = 0.015) but lessened at 12 h (69% vs 42%; P = 0.060) and was insignificant at the end of the 24-h treatment period (79%, vs 73%; P = 0.752). Apart from hypotension, transient in three cases and sustained in one whose later echocardiographic examination demonstrated left systolic ventricular dysfunction, propafenone was well tolerated.

Conclusion: Although there is no significant difference in the rates of conversion 24 h after treatment, propafenone works faster than placebo in achieving sinus rhythm. This rapid action of oral propafenone can be useful to solve quickly the clinical problems of a high proportion of patients arriving at the emergency department with acute atrial fibrillation.