Impact of intracardiac electrophysiologic testing on the management of elderly patients with recurrent syncope or near syncope.

Seventy-five patients, 75 years of age and over, experienced recurrent syncope, with the etiology remaining unclear but presumably cardiogenic, after cardiac and neurologic examinations and noninvasive laboratory testing (including an electrocardiogram and ambulatory electrocardiographic monitoring). The mean number of previous syncopal spells was 14 (range, 1 to 64) over a mean of 36 months (range, 1 to 480 months). These patients underwent invasive electrophysiologic testing and a potential cause for syncope was identified in 68%. Abnormal findings at electrophysiologic testing included: sinus node dysfunction (55%); abnormal His-bundle conduction (39%); and ventricular tachycardia (14%), with some patients having more than one abnormality. No major complications were associated with the electrophysiologic testing. Patients were subsequently treated with permanent cardiac pacing or antiarrhythmic drugs or both, depending upon results of the electrophysiologic study. Follow-up examinations (mean of 26 months; range, 1 to 70) were possible in 90% of patients. No further syncope occurred in 84% of patients with an abnormal electrophysiologic study who received subsequent therapy to prevent the identified abnormality. Thus, in this difficult group of patients with recurrent syncope of uncertain etiology, electrophysiologic testing was safe and indicated abnormalities of conduction or rhythm in 68% of patients; treatment to correct these abnormalities prevented recurrent syncope in 84%.