Tilt test in elderly patients with syncope of unknown etiology: experience with pharmacological stimulation with nitroglycerin.

UNLABELLED: The importance of head-up tilt testing has been demonstrated in the evaluation of patients with unexplained syncope. In elderly patients, the prevalence of syncope increases, is associated with a worse outcome and frequently requires several complementary tests.

OBJECTIVES: To evaluate the utility of head-up tilt testing with sublingual nitroglycerin as a provocative agent, in elderly patients with unexplained syncope.

METHODS: We studied 46 consecutive patients aged >65 years (74 +/- 6 years, 56.5% female) with unexplained syncope. In 25 patients (54%), we found no cardiac anomaly. The remaining patients had hypertensive (14 patients) or ischemic (7 patients) heart disease. The protocol included carotid sinus massage in decubitus and after passive orthostatism. Tilt testing was performed with continuous electrocardiographic and blood pressure monitoring, at a 70 degrees tilt for 20 minutes. In the absence of syncope, we administered 500 mcg of nitroglycerin with an additional 20 minutes monitoring. The tilt test was considered positive when there was reproduction of symptoms associated with bradycardia and/or arterial hypotension (cardioinhibitory, vasodepressor or mixed response). We considered orthostatic hypotension to be present when systolic blood pressure decreased by >20 mmHg or diastolic blood pressure decreased by >10 mmHg during the first 3 minutes after orthostatism; patients with symptoms associated with a progressive and parallel decrease of systolic and diastolic blood pressure during passive tilt testing were considered to have a dysautonomic profile; patients with symptoms and a gradual decrease of blood pressure after nitroglycerin were considered to have an exaggerated response to nitrates.

RESULTS: Symptoms were reproduced in 34 patients (73.9%): 19.6% during passive tilting (neurocardiogenic vasodepressor response--3 patients, carotid sinus hypersensitivity--1 patient, orthostatic hypotension--1 patient, dysautonomic profile--4 patients) and 54.3% after nitroglycerin (neurocardiogenic vasodepressor response--12 patients, mixed--5 patients, cardioinhibitory--2 patients and exaggerated response to nitrates--6 patients). Syncope was neurocardiogenic in 47.8% (passive test--13.6%, after nitroglycerin--86.4%). There was an exaggerated response to nitrates in 16.2% of the patients given nitroglycerin. There were no complications during the test.

CONCLUSIONS: Tilt testing in the elderly with syncope of unknown origin: (1) helps differential diagnosis in etiological study of the syncope and (2) when potentiated by nitroglycerin, it produces a significant increase in positive responses, and identifies a considerable number of patients with an exaggerated response to nitrates.