Oral Verapamil for Paroxysmal Supraventricular Tachycardia

Abstract

The effectiveness and safety of orally administered verapamil [a Ca channel blocker] was tested in 11 patients with frequent paroxysmal supraventricular tachycardia. In a 4-mo. randomized, double-blind, placebo-controlled trial, the frequency of paroxysmal supraventricular tachycardia fell from 0.3 .+-. 0.3 (mean .+-. SD) to 0.1 .+-. 0.1 episodes/day by patient diary (P < 0.05) and from 0.7 .+-. 0.7 to 0.3 .+-. 0.5 episodes per day by Holter monitor (P < 0.05) for placebo and verapamil treatment periods, respectively. Verapamil caused a decrease in the duration of paroxysmal supraventricular tachycardia (in min/day): placebo 27 .+-. 51 by diary, 67 .+-. 111 by Holter; verapamil, 3 .+-. 3 by diary, 1 .+-. 2 by Holter (P < 0.05). Five patients required a total of 35 pharmacologic cardioversions for sustained tachycardia: 2 during verapamil and 33 during placebo (P < 0.01). No verapamil treatment period was shortened due to unacceptable paroxysmal supraventricular tachycardia, but 5 of 22 placebo treatment periods were shortened (P = 0.02). Verapamil was well-tolerated, causing mild constipation in 5 and headache in 1 patient. Oral verapamil was both safe and effective in the long-term treatment of patients with paroxysmal supraventricular tachycardia.