Oral beta-blocker is initially used to prevent the symptons in patients with vasovagal syncope or presyncope. But, beta-blocker treatment may actually cause worsening of symptoms in some patients. The purpose of the present study was to evaluate the efficacy of oral beta-blocker in preventing symptoms during repeat head-up tilt test in patients who had a positive response in initial head-up tilt test.

Patients. Among the 150 patients with unexplained syncope or presyncope who underwent head-up tilt from October 1994 to January 1996, forty-three patients, who were taking beta-blocker and underwent repeat head-up tilted test, were included in this study. Initial head-up tilt test. Each patients was tilted to the 70 degree upright position for 30 minutes. If the test was negative in the baseline tilt, intravenous isoproterenol was started at 1 (micro)g/min and then increased by 1 (micro)g/min every three minutes to al maximum of 5 (micro)g/min while maintaining 70 degree upright position. Repeat head-up tilt test. The test was repeated while each patients was taking atinolol. The repeat test was continued until reaching at the stage where each patient had a positive response in initial test.

1) In initial head-up tilt test, most (91%) of a positive response occured during isoproterenol provocation. 2) In repeat head-up tilt test on atenolol, thirty-four patients(79%) had a negative response. But nine patients(21%) still had a positive response. 3) Nonresponsive group showed younger age and shorter time period to a positive response in initial head-up tilt test than responsive group.

It may be useful to assess the effectiveness of beta-blocker by repeat head-up tilt before deciding long term treatment, especially younger age group.