Long-term effects of theophylline in atrial fibrillation with a slow ventricular response

In 17 patients (aged 78 +/- 9 years) with symptomatic atrial fibrillation and a slow ventricular response not related to drugs, a resting electrocardiogram and 24-hour Holter recording were obtained before and 5 to 6 days after administration of slow-release theophylline (700 mg/day), and successively every 3 months during the long-term phase. Fourteen patients had organic heart disease, and 13 complained of syncope or presyncope, and 4 of asthenia and easy fatigability. At the steady-state evaluation, theophylline significantly increased resting heart rate (HR) by 42%, mean 24-hour HR by 31% and minimal 24-hour HR by 34%. Cardiac pauses > 2,500 ms disappeared or markedly decreased. The daily number of wide QRS complexes increased. Serum theophylline level was 13 +/- 5 ng/ml. During the follow-up period (20 +/- 18 months), the mean daily theophylline dosage was 450 mg and the mean serum theophylline level 9 ng/ml. Seven patients died: 1 because of heart failure, and 6 because of noncardiac death. One patient complained of a syncopal episode during 1 visit. The drug markedly reduced asthenia and easy fatigability. During the long-term phase, HR increased spontaneously in 3 patients, and the treatment was interrupted. In 2 patients, theophylline had to be discontinued because of gastric intolerance. During long-term therapy, HR was similar to that observed at the steady-state evaluation, despite the reduction in daily dosage. The data suggest that theophylline is an effective therapy in most patients with symptomatic atrial fibrillation and a slow ventricular response.