Poor reproducibility of false-positive tilt testing results in healthy volunteers

Positive responses to head-up tilt testing occur in healthy subjects. Howev er, the reproducibility of "false-positive" tilt testing results has not be en clarified. To study the reproducibility of "false-positive" responses, w e prospectively performed 2 tilt tests separated by 1 to 10 (mean 3.2) week s in 20 healthy males aged 23 to 40 years (mean 30 years). The baseline til t test (80 degrees for 30 minutes) ended positive in 4 (20%) subjects on th e initial test and 2 (10%) on the second test with only 1 (5%) who had cons ecutive positive responses. No additional positive responses were noted dur ing the isoproterenol (0.01 mu g/kg/min)-tilt test for 10 minutes. We demonstrated that a false-positive response occurred in 5 (25%) of 20 yo ung males who underwent 2 tilt tests, however, only 1 (5%) subject had cons ecutive positive responses. Poor reproducibility may be characteristic of f alse-positive responses in head-up tilt testing.