The beneficial effects of verapamil in chronic atrial fibrillation.

Digitalis preparations frequently fail to control heart rate in many patients who have chronic atrial fibrillation, particularly during physical exertion. The effects of orally administered verapamil, 160 to 240 mg/day, on the heart rate at rest and during mild exercise were studied in 23 digitalized patients with chronic atrial fibrillation of various causes. Verapamil substantially reduced the excessive heart rate response to exercise in well-digitalized patients who had chronic atrial fibrillation.