A randomized study of tilt test angle in patients with undiagnosed syncope

Can J Cardiol. 2001 Oct;17(10):1051-7.

Abstract

Background: A widely used tilt test protocol involves passive head-up tilt followed by tilt with isoproterenol infusion if necessary. Little is known about the effects of passive tilt angle and duration, duration of isoproterenol infusion or hemodynamic diagnostic criteria.

Objectives: To assess whether tilt angle and duration of isoproterenol infusion affected test outcomes in patients with undiagnosed syncope.

Patients and methods: Two hundred one syncope patients (87 men, age 45+/-20 years, median five faints) were randomly assigned to undergo 60 degrees versus 80 degrees tilt for 45 min, then, if necessary, to receive isoproterenol 30 ng/kg/min for 20 min or less. Positive tests ended in presyncope or syncope.

Results: Overall, 49% and 71% of patients fainted at 60 degrees and 80 degrees, respectively (P=0.002). In the drug-free stage, 27% and 50% of patients fainted at 60 degrees and 80 degrees, respectively (P=0.0005). In the 119 patients who received isoproterenol, there was no significant difference in the probability of a positive isoproterenol test at 60 degrees and 80 degrees, respectively (31% compared with 43% of exposed patients, P=0.25). Symptoms developed in adults during drug-free tilt linearly with time at both 60 degrees and 80 degrees at 0.6% and 1.1%/min, respectively, while symptoms during isoproterenol tilt reached an asymptote after about 10 min. Rate-systolic pressure products of 7000 mmHg/min and 9000 mmHg/min best distinguished positive from negative passive and isoproterenol stages, respectively.

Conclusions: The positive yield of passive tilt tests is higher at 80 degrees and increases linearly with the duration of tilt. A subsequent 10 min isoproterenol infusion maximizes positive yield. Evidence-based outcome criteria accurately distinguish negative from positive tilt tests.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Blood Pressure / drug effects
  • Blood Pressure / physiology
  • Bronchodilator Agents*
  • Female
  • Heart Rate / drug effects
  • Heart Rate / physiology
  • Humans
  • Isoproterenol*
  • Male
  • Middle Aged
  • Posture / physiology
  • Syncope / diagnosis*
  • Syncope / physiopathology*
  • Tilt-Table Test*
  • Time Factors

Substances

  • Bronchodilator Agents
  • Isoproterenol