Comparison of Troponin in a Prehospital Blood Sample and Risk Scores.

Background/Objectives: Prehospital identification of non-ST-elevation acute coronary syndrome remains unresolved, and available risk scores incorporate troponin categorically. We compared the discriminative performance of cardiac troponin I measured in a blood sample obtained at first prehospital medical contact, analysed as a continuous variable, against the HEART, GRACE, and TIMI scores for predicting 30-day major adverse cardiac events. Methods: We conducted a prospective cohort study in 333 adults with non-traumatic chest pain suggestive of non-ST-elevation acute coronary syndrome, which was attended by two physician-staffed advanced life support units. Venous blood was drawn at first medical contact and analysed later in the laboratory; the results were not available during patient care. All three scores used this same determination as their troponin component. The primary outcome was a composite of all-cause mortality, type 1 myocardial infarction, and unplanned coronary revascularisation at 30 days. Results: The primary outcome occurred in 82 patients (24.6%). Prehospital troponin discriminated better (area under the curve 0.916, 95% CI 0.875-0.952) than TIMI (0.817), GRACE (0.767), and HEART (0.721); all comparisons were p < 0.001. An exploratory rule-out threshold of 80 ng/L identified 61 patients (18.3%) with no events (sensitivity and negative predictive value 100%, exact 95% CI 95.6-100 and 94.1-100), whereas the ≥780 ng/L stratum showed an event rate of 69.4%. Conclusions: A blood sample obtained at first prehospital medical contact carries substantial prognostic information that clinical scores discard by categorising it. Because it was analysed subsequently in the laboratory, these findings do not evaluate a real-time strategy; they support development and validation of point-of-care devices.