Recurrent ventricular tachyarrhythmias required multiple resuscitative efforts with electrical countershock in a 45-year-old woman with previously undiagnosed asymptomatic congenital prolongation of the Q-T interval. This patient represents the oldest person with symptoms relating to idiopathic prolongation of the Q-T interval found in the literature. Exacerbating factors, including diuretic-induced hypokalemia and the concomitant administration of perphenazine, were present. In such cases, initially refractory to therapy with antiarrhythmic agents, insertion of a transvenous pacemaker with overdrive suppression of the ventricular tachyarrhythmias may be lifesaving, allowing for the institution of therapy with agents that can selectively shorten the Q-T interval.