A randomized study of tilt test angle in patients with undiagnosed syncope.
Bibliographic record
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.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".