High-Sensitivity Cardiac Troponin I and Clinical Outcomes of Major Acute Cardiac Events

Background: The long-term benefit of sex-specific 99th percentile upper reference limits (URLs) in conjunction with high-sensitivity cardiac troponin assays for suspected acute coronary syndrome (ACS) are emerging. We evaluated the long-term outcomes of patients reclassified by this approach using the Beckman Coulter Access high-sensitivity troponin I (hs-cTnI) assay. Methods: A retrospective observational study evaluated 1486 emergency department (ED) patients with hs-cTnI results for 3 years and 80 days. Patients whose values exceeded the sex-specific URL but remained below the conventional URL were identified and compared with non-reclassified controls. Results: Reclassification occurred 30% more frequently in women (7.6%, 68/893) compared to men (5.7%, 34/593) and demonstrated higher rates of major adverse cardiac events (MACEs), coronary artery disease, and cerebrovascular disease. Among reclassified men, myocardial infarction (MI) was more often followed by death. Among women, reclassification was associated with MI or death, but rarely both. Time to first post-ED MACE was significantly longer in reclassified patients. In a Cox regression model, reclassification independently predicted a 52.5% lower hazard of MACE over time (P = 0.016). The regression model also described Class 1 obesity as protective, with a 68.2% hazard reduction vs normal weight (P < 0.001). Conclusions: Integration of sex-specific URLs and a hs-cTnI assay identified patients at increased cardiovascular risk, yet was associated with improved long-term outcomes, suggesting potential clinical value. Findings also reinforce the obesity paradox, with Class 1 obesity linked to reduced MACE risk.