[Facilitating effect of propafenone pretreatment in the interruption of atrial flutter by transesophageal pacing].

Transesophageal atrial pacing is effective in the interruption of atrial flutter, and being simple and minimally invasive, is easily performed even on outpatients. The influence of antiarrhythmic drugs on this procedure is controversial. We investigated whether the administration of oral propafenone may facilitate the procedure. Thirty patients with type I atrial flutter were randomized into two groups in which transesophageal pacing was attempted, respectively, without treatment (Group A) and after oral administration of propafenone 600 mg (Group B). Transesophageal pacing was effective in interrupting atrial flutter in 53% (8/15) of patients in Group A and in 85% (13/15) of patients in Group B. A significant lengthening of the flutter cycle was observed in patients treated with propafenone (261 +/- 23 vs 217 +/- 25 ms, p < 0.01). Sinus rhythm resumed at a shorter paced cycle in patients of Group A (166 +/- 13 vs 187 +/- 14 ms, p < 0.01). The transesophageal threshold for stable atrial capture was significantly lower in Group A (20.5 +/- 0.2 vs 23.3 +/- 1.2 mA, p < 0.01). In no patient the threshold for atrial capture was higher than the pain threshold. We did not observe abrupt enhancement of atrioventricular conduction. We can conclude that propafenone is effective and safe when used with transesophageal pacing in the termination of atrial flutter. The depressing effect of the drug on intraatrial conduction and the possible stabilizing effect on the reentry circuit appear to be outweighed by the positive effect of propafenone on the excitable gap of the circuit, facilitating its capture and account for the beneficial effect of the drug on arrhythmia termination.