Transesophageal overdrive atrial pacing is effective and safe for
atrial flutter termination. The influence of
antiarrhythmic drug therapy on this procedure is controversial. In this study, we investigated whether oral
propafenone may facilitate this procedure. Thirty patients with type I
atrial flutter were randomized into 2 groups in which transesophageal pacing was attempted: group A, without treatment; and group B, after
oral administration of
propafenone 600 mg. Transesophageal pacing was effective in interrupting
atrial flutter in 53% of patients (8 of 15) in group A and in 87% of patients (13 of 15) in group B. A significant lengthening of the flutter cycle was observed with respect to the baseline in patients given
propafenone (261 +/- 23 vs 217 +/- 25, p < 0.01). Sinus rhythm resumed at a shorter paced cycle in group A patients (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, p < 0.01). In no patient was the threshold for atrial capture higher than the pain threshold. We did not observe abrupt enhancement of atrioventricular conduction. We conclude that
propafenone is effective and safe when used with transesophageal pacing in the termination of
atrial flutter. The slowing 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 accounting for the beneficial effect of the
drug on
arrhythmia termination.