Diagnostic Value of Nitrate Stimulated Tilt Testing Without Preceding Passive Tilt in Patients with Suspected Vasovagal Syncope and a Healthy Control Group

BACKGROUND: The contribution of the passive tilt phase, in a combined nitrate stimulated tilt protocol may be low yielding. In order to develop a shortened, and thus easier to perform test, we investigated the optimal duration of a nitrate tilt protocol without a preceding passive phase. METHODS: Thirty-eight consecutive patients (18F/20M; mean age 46 +/- 16) with clinically suspected vasovagal syncope and 31 control subjects (15F/16M; mean age 40 +/- 18) were tested. The subjects were tilted to 70 degrees for a maximum period of 30 minutes, and sublingual nitroglycerin 0.4 mg spray was administrated directly after attaining erect posture. Receiver operator characteristics (ROC) analysis was done to determine the optimal test duration. RESULTS: In the patient group 31 (82%) and in controls 5 (16%) had a positive test. Sensitivity, specificity, and accuracy at test end were 82, 84, and 83%, respectively. ROC analysis revealed that a maximum accuracy of 83% was attained at 14 minutes, with a sensitivity and specificity of 79 and 87%, respectively. CONCLUSION: Nitrate stimulated tilt testing, without a preceding passive tilt phase, and limited to a test duration of 15 minutes, provides an accurate, sensitive, and specific method to provoke vasovagal reactions in subjects with clinically suspected vasovagal syncope.