SHORTENED HEED-UP TILT RESTING POTENTIATED WITH SUBLINGUAL NITROGLYCERIN IN PATIENTS WITH UNEXPLAINED SYNCOPE

Background Head-up tilt testing is extensively used to determine the v asovagal origin of syncope in patients with otherwise unexplained loss of consciousness, although issues remain regarding the method of the test. The diagnostic value of a shortened head-up tilt test potentiate d with sublingual nitroglycerin was assessed in patients with unexplai ned syncope. Methods Two hundred two patients (mean age 49 +/- 19 year s) with syncope of unknown origin and 34 subjects in a control group ( mean age 45 +/- 17 years) were studied. The patients and the subjects in the control group were tilted upright to 60 degrees for 20 minutes. If syncope did not occur, sublingual nitroglycerin (400 mu g) was adm inistered, and observation was continued for 25 more minutes. Results During the unmedicated phase syncope occurred in 22 (11%) patients and in one member of the control group. After nitroglycerin was administe red, syncope occurred in 119 (59%) patients and in 1 (3%) member of th e control group. False-positive response (exaggerated response) was ob served in eight (4%) patients and in Four (12%) subjects in the contro l group. The total positivity rate of the test was 70% with a specific ity rate of 94%, Conclusions Short-duration head-up tilt test potentia ted with sublingual nitroglycerin provides an adequate specificity and positivity rate in patients with unexplained syncope.