• Y Mineda, M Sumiyoshi, Y Nakazato, Y Nakata, and H Yamaguchi.
• Department of Cardiology, Juntendo University Izunagaoka Hospital, Shizuoka.
• J Cardiol. 2000 May 1; 35 (5): 363-71.

AbstractThe usefulness of 80 degrees head-up tilt testing with and without low dose isoproterenol provocation was evaluated for the diagnosis of neurally mediated syncope (NMS) in Japanese. Head-up tilt testing was performed in 114 consecutive patients with clinical diagnoses of NMS (68 men, 46 women, mean age 46 +/- 21 years), and 57 times in 36 healthy volunteers (26 men, 10 women, mean age 31 +/- 8 years) who had no history of syncope or presyncope. Head-up tilt testing used an 80 degrees angle for 30 minutes (passive tilt), and if the passive tilt resulted in negative response, isoproterenol was infused at 0.01-0.02 microgram/kg/min and the tilt repeated for 10 minutes (isoproterenol tilt). A positive response was defined as the development of syncope or a presyncopal state associated with hypotension, bradycardia or cardiac arrest. The sensitivities of passive tilt testing for a positive response after 5-, 10-, 15-, 20-, 25- and 30-minute tilting were 1%, 9%, 14%, 19%, 24%, and 28%, respectively, and specificities after 5-, 10-, 15-, 20-, 25- and 30-minute tilting were 100%, 95%, 91%, 88%, 86%, and 84%, respectively. The sensitivities of isoproterenol tilt testing with 0.01 and 0.02 microgram/kg/min were increased to 37% and 48%, respectively. This improvement was statistically significant between the passive tilt and isoproterenol tilt testing with a dose of 0.02 microgram/kg/min (p < 0.01). However, specificities were comparable with those of the passive tilt testing (84% and 82%, respectively). In conclusion, 80 degrees passive tilt testing for 30 minutes showed a low sensitivity (28%) but acceptable specificity (84%). Low-dose isoproterenol provocation was useful for improving sensitivity (48%) while maintaining a comparable specificity (82%).

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