[Efficacy of disopyramide in the treatment of atrial flutter with overdrive pacing].

Thirty patients with long-standing (mean 30 days) type I atrial flutter (AF) were treated with overdrive atrial pacing. To evaluate the effect of pretreatment with disopyramide (DISO), the study population was divided into 3 groups of 10 patients each: no therapy (Group A); intravenous DISO (maximum dose 250 mg in 1 hour) (Group B), oral DISO (400 mg/day for 4 days) (Group C). The mean cycle length of AF was 215 +/- 24 ms in Group A, 222 +/- 28 in B and 224 +/- 11 in C (NS). After DISO, AF cycle length increased to 287 +/- 24 in Group B (p less than 0.001) and to 264 +/- 29 in C (p less than 0.001). Overdrive pacing was performed from a maximum of 3 atrial sites up to the shortest paced cycle of 150 ms. Reversion to sinus rhythm (SR) occurred in 20% of patients in Group A, 70% in B and 50% in C. In all these cases SR was obtained with paced cycle length that was 70-90% of the baseline cycle length. Pacing was performed from a mean number of 2.1 sites per patient in Group A, 1.2 in B and 2.0 in C. Atrial fibrillation occurred in 7, 3 and 4 patients, respectively. Acceleration of atrial flutter to a faster form of AF occurred in 3, 3 and 4 patients, respectively. The administration of DISO prior to overdrive atrial pacing improves the rate of conversion to SR and allows an easier stimulation protocol with a lower incidence of pacing-induced atrial fibrillation. The administration of DISO is beneficial when overdrive atrial pacing is performed for the treatment of long standing AF in patients with organic heart disease.