Remnant cholesterol and mortality in patients with acute myocardial injury: a retrospective cohort study

Introduction Remnant cholesterol (RC) is increasingly recognized as a key driver of residual cardiovascular risk. However, its prognostic significance specifically within the heterogeneous population of patients with acute myocardial injury remains largely underexplored. Although these patients face a poor long-term prognosis, the specific metabolic risk factors driving these adverse outcomes remain poorly understood. Purpose To investigate the association between baseline RC levels and 1-year all-cause and cause-specific mortality in patients hospitalized with acute myocardial injury. Methods This retrospective cohort study utilized data from a large-scale electronic medical record database between January 2013 and December 2022. The study included 60,969 patients hospitalized with acute myocardial injury, defined by cardiac troponin elevation ( > 99th percentile upper reference limit) with a dynamic rise and/or fall of ≥ 20%. Patients were categorized into quartiles (Q1 - Q4) based on baseline RC levels (calculated as TC minus HDL-C and LDL-C). The primary outcome was 1-year all-cause mortality. Secondary outcomes included cardiovascular death and cancer death. Multivariable Cox proportional hazards models and restricted cubic splines (RCS) were employed to estimate hazard ratios (HR) and assess dose-response relationships, adjusting for demographics, comorbidities, and baseline medication use. Results During the 1-year follow-up, 11,106 deaths were recorded. In the fully adjusted model, elevated RC levels were significantly associated with an increased risk of all-cause mortality. Patients in the highest quartile (Q4) had a 13% higher risk of death compared with those in the lowest quartile (Q1) (HR: 1.13, 95% CI: 1.07 - 1.19). Regarding cause-specific mortality, high RC was independently associated with cardiovascular death (HR: 1.11, 95% CI: 1.03 - 1.20) and cancer death (HR: 1.50, 95% CI: 1.24 - 1.81). RCS analysis revealed that while the unadjusted relationship was U-shaped, the association became linear and positive after full adjustment. Notably, the increased mortality risk associated with high RC persisted even among patients with low LDL-C ( < 70 mg/dL) and those with lower magnitude of troponin elevation. Conclusion In this large-scale cohort of patients with acute myocardial injury, elevated RC levels were associated with an increased risk of all-cause, cardiovascular, and cancer mortality. These findings highlight the importance of RC assessment for risk stratification and potential therapeutic targeting in this high-risk population.