Development of a risk score for intramyocardial hemorrhage in elderly STEMI patients after primary PCI: a retrospective cohort study with propensity score matching analysis

Objective This study aimed to identify independent risk factors for intramyocardial hemorrhage (IMH) and develop a clinical risk score for predicting IMH in elderly patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI). Methods We conducted a single-center retrospective observational study of 232 consecutive elderly patients (≥60 years) with STEMI who underwent primary PCI between August 2020 and August 2024 and completed cardiac magnetic resonance (CMR) imaging 3–7 days post-procedure. Patients were classified into IMH ( n = 77) and non-IMH ( n = 155) groups based on CMR findings. Clinical, laboratory, angiographic, and procedural data were collected. Univariate and multivariate logistic regression analyses were performed to identify independent predictors. A risk score (IMH-RS) was developed and validated internally. Results The incidence of IMH was 33.2% (77/232). Multivariate logistic regression identified the following independent predictors: renal insufficiency (OR = 2.95, 95% CI: 1.41–6.18, P = 0.004), left anterior descending artery involvement (OR = 2.01, 95% CI: 1.02–3.97, P = 0.044), door-to-balloon time >45 min (OR = 2.55, 95% CI: 1.36–4.78, P = 0.003), triple-vessel disease (OR = 6.12, 95% CI: 2.51–14.88, P < 0.001), elevated B-type natriuretic peptide (per 100 pg/L increase: OR = 1.25, 95% CI: 1.05–1.49, P = 0.012), and reduced left ventricular ejection fraction (per 1% increase: OR = 0.94, 95% CI: 0.91–0.97, P < 0.001). An integer-based risk score (IMH-RS) ranging from 0 to 10 was developed, demonstrating good discrimination (AUC = 0.82, 95% CI: 0.77–0.87) and effectively stratifying patients into low- (12.5% IMH), intermediate- (38.2%), and high-risk (68.9%) groups ( P < 0.001). Conclusion IMH is common in elderly STEMI patients after primary PCI and is independently associated with renal dysfunction, extensive coronary disease, delayed reperfusion, and markers of myocardial injury. The IMH-RS score, derived from a comprehensive integration of patient comorbidities, coronary anatomy, procedural timing, and myocardial injury severity, represents a novel and practical bedside tool for early risk stratification. This integrative approach provides a more holistic risk assessment than individual predictors alone. The score may guide targeted management strategies to mitigate microvascular injury.