Remnant Cholesterol Paradox: Higher Levels Are Associated With Reduced Mortality in Critically Ill Patients With Heart Failure

BACKGROUND: Remnant cholesterol (RC) is a significant cardiovascular risk factor, but its prognostic value in critically ill patients with heart failure remains inadequately characterized. This study evaluated the association between RC levels and all-cause mortality in this population. METHODS: This retrospective cohort study used data from 3750 critically ill patients with heart failure from the Medical Information Mart for Intensive Care III/IV databases. RC was calculated as total cholesterol minus high-density and low-density lipoprotein cholesterol. Optimal RC thresholds were determined by X-tile: low (<22.7 mg/dL), intermediate (22.7-54.0 mg/dL), and high (≥54.0 mg/dL). Primary end points were 30-day and 1-year all-cause mortality. RESULTS: Mortality occurred in 16.9% of patients at 30 days and 34.1% at 1 year. After multivariable adjustment, each 10 mg/dL increment in RC was associated with reduced risks of 30-day (hazard ratio [HR], 0.88 [95% CI, 0.82-0.95]) and 1-year mortality (HR, 0.92 [95% CI, 0.88-0.97]). Compared with the low RC group, the high RC group exhibited significant reductions in 30-day (HR, 0.52 [95% CI, 0.31-0.87]) and 1-year mortality (HR, 0.61 [95% CI, 0.44-0.8]7). Restricted cubic spline analysis confirmed a linear inverse relationship. CONCLUSIONS: Higher RC levels are independently associated with lower all-cause mortality in critically ill patients with heart failure. These findings suggest a protective, context-dependent role of RC during acute illness.