Ventricular tachyarrhythmias induced by disopyramide and other similar anti-arrhythmic drugs.

Two patients with atrial arrhythmias are described who developed ventricular tachyarrhythmias shortly after starting disopyramide therapy. One patient had manifested ventricular tachycardia while on quinidine therapy earlier and the other patient, who died, had survived ventricular tachycardia and fibrillation complicating both quinidine and lidoflazine therapy 5 years earlier. We advise against the use of lidoflazine in patients with previously documented 'quinidine syncope' and caution that ventricular tachyarrhythmias appearing for the first time with the administration of disopyramide should be considered to be drug-induced until proved otherwise.