Abstract
<jats:p>Background: ST-elevation myocardial infarction (STEMI) remains a major cause of global mortality. While troponin is the gold-standard biomarker for myocardial injury, a subset of patients presents with troponin levels below the clinical "rule-in" threshold upon hospital admission. The long-term prognostic significance of these initial "low-troponin" presentations in a large-scale population remains insufficiently characterized. Methods: We conducted a retrospective multicenter cohort study using the "KINERET" database, analyzing 8,394 patients diagnosed with STEMI who underwent percutaneous coronary intervention (PCI) at four academic medical centers in Israel between 2016 and 2023. Patients were stratified into two groups based on ESC rule-in criteria for high-sensitivity cardiac troponin (hs-cTn) at admission: a High trop group (above rule-in cutoff) and a Low trop group (below rule-in cutoff). The primary outcome was all-cause mortality at 5 years. Results: Of the 8,394 patients (mean age 68.3±13.3 years; 76% male), 36.5% (n=3,064) presented with troponin levels below the rule-in cutoff. Patients in the High trop group were older and had a higher prevalence of comorbidities, including heart failure (46.7% vs. 28.7%) and chronic kidney disease (13.9% vs. 9%). The Low trop group demonstrated significantly higher survival rates at both 1 year (92.9% vs. 84.0%, p<0.001) and 5 years (85.7% vs. 75.0%, p<0.001). After adjusting for age, sex, and comorbidities in a multivariate Cox regression model, initially elevated troponin remained a robust independent predictor of 5-year mortality (HR 1.15, 95% CI 1.14-1.16, p<0.001), alongside age >75, female sex, and chronic kidney disease. Conclusions: STEMI patients presenting with initial troponin levels below the diagnostic rule-in threshold have a significantly better short- and long-term prognosis compared to those with early troponin elevation. Moreover, admission troponin levels serve as a powerful predictor of 5-year mortality and may be used as an independent prognostic factor following STEMI.</jats:p>