Long-Term Prognosis of Non-Ischaemic Myocardial Injury in the Emergency Department: A Propensity Score-Adjusted Study

Background/Objectives: Cardiac troponin measurement in the emergency department frequently detects non-ischaemic myocardial injury. Although this condition accounts for most troponin elevations, its clinical management remains uncertain. This study aims to determine its prevalence and evaluate its prognostic implications at a 5-year follow-up.

Methods

We conducted a retrospective cohort study of 2715 emergency department patients undergoing systematic cardiac troponin testing, excluding type 1 or 2 acute myocardial infarctions. Patients with non-ischaemic myocardial injury (n = 254, 9.4%) were compared to controls (n = 2461, 90.6%) using propensity score methods (overlap weighting and 1:1 matching).

Results

Before matching, patients with non-ischaemic injury were older with higher comorbidities. After overlap weighting, the risks of all-cause mortality (hazard ratio [HR] 1.75, 95% CI 1.45–2.11; p < 0.001) and major adverse cardiovascular events (HR 1.78, 95% CI 1.49–2.13; p < 0.001) remained significantly higher in the non-ischaemic injury group over a median 5.07-year follow-up. In cause-specific Cox analysis, heart failure readmission rate was increased among survivors (HR 1.64, 95% CI 1.16–2.30; p = 0.005); however, when accounting for all-cause mortality as a competing risk, this association attenuated (subdistribution hazard ratio [sHR] 1.27, 95% CI 0.90–1.80; p = 0.168). Recurrent myocardial infarction readmissions did not differ between groups (cause-specific HR 1.61, 95% CI 0.70–3.72; p = 0.265; Fine–Gray sHR 1.26, 95% CI 0.55–2.91; p = 0.596).