Utility of sublingual Isosorbide Dinitrate During Upright Tilt Testing for the Diagnosis of Vasovagal Syncope

pp 471-475

Abstract

Background and objective

Head-up tilt testing allows identification of patients with syncope, prone to hypotension and bradycardia development. However, the test has provided diagnostic results in a proportion of patients 48% (range 32%-74%). Isoproterenol infusion is relatively frequent and may lead to early interruption of the test, increasing time and costs. The present study was undertaken to assess the diagnostic value of sublingual isosorbide dinitrate during upright tilt testing for identification of vasovagal syncope.

Material and methods

One hundred and thirty-one consecutive patients suspicious of vasovagal syncope and 13 asymptomatic controls underwent head-up tilt testing. Patients were tilted 60 degrees for 45minutes, followed by 80 degrees tilting for 15 minutes, without medication. In the absence of symptoms 5mg of isosorbide dinitrate were administered sublingually and tilting was continued for additional 10 minutes. A test was considered positive when syncope in association with hypotension, bradycardia or both was achieved.

Results

During the drug free phase 37 patients (28%) developed syncope. After isosorbide dinitrate administration, syncope occurred in other 48 patients (52%). Two patients developed minor symptoms in association with hypotension. All the controls had negative upright tilt testing (both with and without isosorbide dinitrate administration). No patient had side effects.

Conclusions

Sublingual isosorbide dinitrate is an useful tool to elicit a vasovagal syncope during upright tilt testing. It was found to be fairly sensitive and specific.