Incidence, Clinical Presentation and Outcome in Patients with Long Asystole Induced by Head-up Tilt Test

Long asystole during head-up tilt test is uncommon. When the duration is more then 5 seconds, it has been called malignant. Although recent reports have demonstrated long asystole response is quite a benign course. Owing to most of these reports came from western countries, ethnic variation is possible. The clinical data about this subset of patients are reported herein. Head-up tilt test was employed for 604 patients with syncope of unknown origin. The protocol included 30min passive tilt test and 30min isoproterenol infusion which increased the heart rate up to 20% from baseline. The response patterns were analyzed and categorized. The prolonged asystole was searched. Follow up was made at the outpatient clinic or by phone during October 2004. Two hundred forty-two patients (40.1%) had positive response. 172 patients (71.1%) with the mixed type, 60 patients (24.8%) with the vasodepressive type and only 10 patients (4.1%) with the cardioinhibitory type. Three patients (1.2%) had prolonged asystole. One young girl and two elderly males with atrial fibrillation. The young girl received midodrine treatment and stop the medication 6 months later with only few recurrence of syncope. The two elderly received pacemaker implantation without syncope recurrence. The incidence of long asystole during head-up tilt test in our patients was much lower than that of western countries. Head-up tilt test may be an helpful tool for evaluation of syncope in elderly patients with atrial fibrillation.