In this study, the safety and efficacy of long-term
therapy with
disopyramide phosphate were evaluated in 40 patients with documented, recurrent, symptomatic
tachyarrhythmias. Twenty-one (53%) of the patients had organic
heart disease, and nine of these patients had compensated
congestive heart failure. The
tachyarrhythmias which were treated were
paroxysmal supraventricular tachycardia (21 patients),
paroxysmal atrial fibrillation (six patients), and paroxysmal
ventricular tachycardia (13 patients). In each patient there was evidence, from continuous ECG monitoring or electrophysiologic testing, that
disopyramide would be effective
therapy, and each patient was able to tolerate
disopyramide (no side effects or tolerable side effects) during an initial trial period of 1 to 2 weeks. Dosages of
disopyramide were 400 to 1600 mg/day (994 +/- 320 mm/day). During long-term
therapy, side effects were reported by 28 (70%) of the patients. The side effects were usually
anticholinergic, and were usually a continuation of side effects noted during the initial trial period. None of the patients had idiosyncratic reactions to
disopyramide. Most of the patients found side effects to be tolerable; however, in seven patients it was necessary to discontinue
disopyramide after 1 to 8 (6 +/- 3) months. Actuarial incidence of intolerable side effects was 21 +/- 7% at 12 months. Nine (22%) of the 40 patients had symptomatic recurrences of
tachyarrhythmia after 3 to 32 (15 +/- 9) months of
therapy. Actuarial incidence of
drug ineffectiveness was 32 +/- 10% at 24 months.
Disopyramide was both effective and tolerated in 24 (60%) of the patients, who were followed for 2 to 64 (23 +/- 16) months.(ABSTRACT TRUNCATED AT 250 WORDS)