Efficacy of verapamil in exercise-induced ventricular tachycardia.
The antiarrhythmic efficacy of verapamil was determined by serial treadmill testing in 16 patients with reproducible exercise-induced ventricular tachycardia (VT). Twelve of the 16 patients responded to verapamil, 0.2 mg/kg intravenously; in 8 of these 12 responders, an oral verapamil regimen of 160 to 320 mg given every 8 hours also prevented exercise-induced VT. Plasma verapamil concentration was significantly higher in the responders than in the nonresponders to intravenous verapamil, but levels were similar in responders and nonresponders to oral therapy. The 8 responders to the oral drug were followed up while receiving verapamil therapy for 6 to 22 months (mean 15), and exercise-induced VT did not recur in any patient. Five of the 8 responders also had concomitant spontaneous VT unrelated to exercise which verapamil suppressed initially as well: 4 remained free of spontaneous VT, while 1 patient had recurrence of spontaneous VT. Thus, in patients with exercise-induced VT, verapamil is a promising alternative therapy to beta-adrenergic blocking agents. The effectiveness of verapamil is consistent with a mechanism of arrhythmogenesis involving calcium channels.
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D007263:Infusions, Parenteral; D008297:Male; D008875:Middle Aged; D013610:Tachycardia / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D014700:Verapamil / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*
D014700:Verapamil