Methodology of head-up tilt testing in patients with unexplained syncope

Abstract

Prolonged 60° head-up tilf has been shown to be valuable in the investigation of unexplained syncope, diagnosing neurally mediated bradycardia/hypotension or malignant vasovagal syndrome. To evaluate the methodology of tilt testing, the following were examined: reproducibility of results, tilt duration, angle of tilt, method of tilt support and effect of age in patients and control subjects.Seventy-one patients with recurrent unexplained syncope underwent 60 min of 60° tilt; 53 (75%) had an abnormal test with vasovagal syncope at 24 ± 10 min (mean ± SD). Tilting to 60° resulted in an abnormal test in only 2 (7%) of 27 control subjects without cardiovascular symptoms (p < 0.001); and 5 (15%) of 34 patients with syncope and documented conduction tissue disease (p < 0.001). of 15 youthful fainters, 3 (20%) had vasovagal reactions as did 1 (8%) of 12 asymptomatic youthful control subjects. These 12 control subjects also underwent tilting with a saddle support and 7 (67%) had vasovagal reactions.It is concluded that uk duration of lilting at 60° should be 45 min (mean time to syncope +2 x SD in the 53 patients with abnormal results). Twenty percent of patients with an abnormal tilt test may not demonstrate syncope with repeat tilting. Saddle tilt testing in unexplained syncope may result in a loss of specificity. Tilting at <60° results in a loss of sensitivity. Head-up tilt may be less useful in youthful subjects with vasovagal syncope than in other subjects.