Antiarrhythmic efficacy of ethacizine assessed by programmed electrical stimulation in patients with ventricular tachycardia.

The efficacy of ethacizine, a Class Ic drug, was assessed by programmed electrical stimulation (PES), delivering single, double, and triple extrastimuli at paced drives of 100 and 140 beats/min from two right ventricular sites (apex and outflow tract) in 38 patients with recurrent sustained ventricular tachycardia (VT). Underlying disease was coronary artery disease (CAD) in 26 (group I) and other conditions in 12 patients (group II; hypertrophic cardiomyopathy in 7, mitral valve prolapse in 1, and no apparent heart disease in 4). In the baseline study VT was induced in all patients. After a single intravenous dose (0.6-0.7 mg/kg) of ethacizine, VT was still inducible in six patients in group I and seven patients in group II. Ethacizine was administered on a long-term basis to all patients in a dose of 200-400 mg per day. All but one CAD patient remained free of recurrences after a mean follow-up of 16.5 (range 3-22) months, while there were recurrences in six of 12 patients in group II. We conclude that: (1) ethacizine appears to be effective in the treatment of VT in CAD patients; (2) the study demonstrates the clinical utility of PES in the management of VT, although some patients in whom VT remains inducible on ethacizine may have good clinical outcome; and (3) the efficacy of ethacizine in other forms of heart disease remains to be studied.