Effectiveness of intravenous propafenone for conversion of atrial fibrillation and flutter of recent onset.

The efficacy of intravenous propafenone (2 mg/kg) was assessed in 83 consecutive patients: 68 with atrial fibrillation (AF) and 15 with atrial flutter lasting less than 15 days. Conversion to sinus rhythm occurred in 47 patients (57%), including 42 (62%) of those with AF and 5 (33%) of those with atrial flutter (p less than 0.05). The mean time to conversion was 29 +/- 24 minutes. The success rate was strongly affected by arrhythmia duration. Thus, conversion occurred in 40 patients (71%) among the 56 with arrhythmia lasting less than 48 hours but in 7 patients (26%) among the 27 with a longer lasting arrhythmia (p less than 0.0005). Left atrial size (determined echocardiographically in 56 patients) was significantly larger in nonconverters (49 +/- 12 vs 39 +/- 7 mm, p less than 0.0005). In nonconverters the mean ventricular rate decreased from 141 +/- 26 to 104 +/- 22 beats/min (p less than 0.0005). Except for reversible low output state in 3 patients already hemodynamically compromised, no significant side effects were observed. In conclusion, (1) intravenous propafenone allows a quick restoration of sinus rhythm in the majority of patients with AF of recent onset, whereas it seems less effective in atrial flutter; (2) its efficacy is influenced by the duration of the arrhythmia and by left atrial dimensions; (3) the drug allows control of ventricular rate; and (4) its use seems to be safe except in patients with severe cardiac failure.