Reproducibility of head-up tilt testing potentiated with sublingual nitroglycerin in patients with unexplained syncope

Head-up tilt testing (HUTT) potentiated with sublingual nitroglycerin has g ained acceptance as means of diagnosing neurally mediated syncope. To evalu ate the reproducibility of HUTT potentiated with sublingual nitroglycerin, 48 patients with unexplained syncope prospectively underwent 2 consecutive tests 1 to 28 days apart. The initial test ended in syncope in 34 patients (71%). In 9 patients (19%) the test was positive during the drug-free phase , whereas 25 patients (52%) had syncope after nitroglycerin administration. Of these 34 patients with an initial positive test result, 27 (79%) had a reproducible outcome on repeat testing. Of 12 patients (25%) with an initia l negative test result, 10 (83%) had a reproducible outcome on repeat testi ng. Of 2 patients (4%) with a first test ending in exaggerated response, bo th had a negative repeat test response. The overall reproducibility of subl ingual nitroglycerin tilt-table testing was 77%. In a group of 23 patients with both positive tests, 19 (83%) had the same response modality (2 vasode pressor, 4 cardioinhibitory, 13 mixed response). In the same group of patie nts, individual trough heart rates correlated well with each other between tests. Finally, in the 27 patients with both positive tests, intrapatient t ime of onset of symptoms did not significantly correlate between tests. Thu s, in patients with syncope of unknown origin, HUTT potentiated with sublin gual nitroglycerin provides an adequate reproducibility when repeated on di fferent days. (C) 1999 by Excerpta Medico, Inc.