Usefulness of head up tilt testing in unknown syncope

The aim of this study was to evaluate the usefulness of head up tilt testing in patients with syncope of unknown origin. Between January 1994 and September 1995, 93 patients were referred for tilt table assessment due to recurrent syncope of uncertain etiology. There were 42 men (mean age 59 years). Thirty healthy volunteers served as a control group. The specific protocol used involved an initial period of supine rest for 15'. Baseline blood pressure (BP) and heart rate (HR) were recorded. This was followed by a tilt to 80 degrees for 30', BP and HR were measured every minute during the procedure. The test was considered positive when symptoms appeared associated with one of the following responses: systolic BP decreased more than 30 mmHg (vasodepressor), bradicardia or asystolia for up to 3 '' (cardioinhibitory) or mixed. Results: The tilt test was positive in 31 of 93 patients (33%). Seventeen patients (55%) had a vasodepressor response, 3 patients (9%) a cardioinhibitory response and 11 patients (36%) mixed responses. The clinical manifestations were 62% near syncope, 19% syncope and the other patients presented dypsnea or dizziness. The symptoms disappeared promptly after adopting the supine position. None of the 30 healthy volunteers developed symptoms. We conclude that head up tilt test is a safe and effective method for identifying a neurocardiogenic origin in a syncope of uncertain etiology.