Clinical use of oral verapamil in chronic and paroxysmal atrial fibrillation

We evaluated the effectiveness of oral verapamil therapy for control of ventricular rate in digitalized patients with atrial fibrillation (AF) with three clinical problems: chronic AF with rapid rate at rest (four patients), chronic AF with accelerated rate during modest exercise (five patients), and rapid rates during paroxysmal AF (four patients). Patients in the first two categories were evaluated both by open-label dosage titration and by a randomized, double-blind, cross-over protocol. In chronic AF with rapid rate of rest, there was a significant reduction in resting heart rate (from 125 ± 7 to 87 ± 14, P<0.01) and in peak exercise heart rate (from 162 ± 33 to 126 ± 25, P<0.01). In chronic AF with rapid rate during exercise, there was also a significant decrease in resting heart rate (from 90 ± 7 to 66 ± 4, P<0.01) and in peak exercise heart rate (from 126 ± 19 to 101 ± 15, P<0.01). These effects continued during longterm follow-up of one to 12 months (mean seven months). In patients with paroxysmal AF, verapamil slowed the ventricular response from 160 ± 24 to 72 ± 4, P<0.01) with only some amelioration of symptoms. Therapy was well tolerated despite a high prevalence (seven of 13 patients) of radiographic cardiomegaly (cardiothoracic ratio > 0.55). We conclude that verapamil is a safe and useful drug for control of ventricular rate in digitalized patients with chronic and paroxysmal AF.