Specificity and total positive rate of head- up tilt testing potentiated with sublingual nitroglycerin in older patients with unexplained syncope

The aim of this study was to assess the specificity and total positive rate of head- up tilt testing (HUTT) potentiated with sublingual nitroglycerin in detecting the vasovagal origin of unexplained syncope in the elderly, since the diagnostic value of this non- invasive test has not yet been proven in this age group. In a period of 3 years, 128 elderly patients (mean age 71.6±5.1 years, 50% males) with syncope of unknown origin, and 101 control subjects matched for age and gender were tilted upright to 60° for 45 minutes. If syncope did not occur, sublingual nitroglycerin (0.4 mg) was administered, and observation was continued for 20 minutes. The positive response was defined as the reproduction of syncope or pre- syncope according to VASIS definition. During the unmedicated phase, syncope occurred in 26 patients (20.3%) and in no members of the control group. After nitroglycerin, 53 patients (41.4%) and 2 control subjects (2%) displayed syncope. The total positive rate of the test was 61.8% with a specificity of 98.0%. In conclusion, HUTT potentiated with sublingual nitroglycerin provides an adequate specificity and total positive rate in old patients with unexplained syncope; therefore it can be proposed as a useful diagnostic tool to detect the vasovagal origin of syncope not only in middle but also in advanced age.