Study of the efficiency of the head-up tilt test with nitroglycerin challenge in the diagnosis of vasovagal syncope

Abstract

Syncope is defined as a transient, self-limited loss of consciousness. It is an important cause of morbidity in general population and the vasovagal syncope (VVS) is a common clinical problem which often leads to hospital admission, multiple office visits, and performing of many diagnostic tests. Head-up tilt table testing (HUTT) is a widely used diagnostic tool, with proved efficiency in diagnosing the many types of VVS. The aim of our study was to assess the efficacy of the HUTT with sublingual nitroglycerin (NTG) challenge for the diagnosis of vasovagal syncope.

Patients and methods: The study groups consisted of 72 patients (37 women, 35 men), mean age (+/-SD) 38.5 +/- 15.7 years, referred to our clinic for syncope of unknown origin and 16 healthy volunteers as control subjects (9 women and 7 men) with a mean age 26 +/- 6.5 years and no history of syncope. The HUTT protocol was performed in the morning after an overnight fast, with a 15 minutes supine equilibration phase followed by a 30 minutes drug free tilt phase at an angle of 70 degrees. If no positive response was recorded, 400 micrograms of NTG spray were given sublingually and the HUTT continued for 20 minutes.

Results: The HUTT was positive in 58 patients (80.5%) and negative in 14 (19.5%) while in the control subjects 4 (25%) had positive HUTT response. The sensitivity of the HUTT protocol with nitroglycerin challenge used in our study was 81% and the specificity was 75% (p<0.0001).

Conclusion: The described HUTT protocol appears to be a simple and efficient tool for the diagnosis of syncope associated with normal ECG and no signs of organic heart disease. The sublingual nitroglycerin challenge was safe to use and showed no side effects while keeping the sensitivity and specificity of the test to an accepted level.