Remnant cholesterol associated with all-cause mortality in oldest-old acute coronary syndrome patients: A cohort study

Previous studies showed that remnant cholesterol(RC) partially explained the residual risk of cardiovascular disease. We tried to test the hypothesis that remnant cholesterol is a risk factor for all-cause mortality and cardiovascular(CV) mortality in oldest-old(>80 years old) patients with acute coronary syndrome(ACS). 699 oldest-old patients with ACS and undergoing coronary angiography(CAG) were included in our study. RC was calculated by fasting total cholesterol(TC) minus low-density lipoprotein cholesterol(LDL-C) and high-density lipoprotein cholesterol(HDL C). With a maximum follow-up period of 10 years, 37 patients were lost to follow-up, and 662 were finally available for statistical analysis. Pearson's correlation test was used to assess the associations between RC and clinical parameter. Multivariable Cox regression analysis was used to identify the association between RC and all-cause mortality. Nelson-Aalen cumulative hazard curves and Fine-Gray plots were used to assess the association between RC and clinical outcomes, including all-cause mortality, major adverse cardiovascular events (MACEs), cardiovascular (CV) mortality, and non-CV mortality. Receiver operating characteristic(ROC) curve was used to compare the discrimination capacity of RC, TC, HDL-C and LDL-C to predict all-cause mortality. Among the 662 oldest-old patients enrolled, 92.90% accepted statin therapy. The average age was 81.87 ± 2.14 years old. Nelson-Aalen cumulative hazard curves showed that the cumulative hazard of all-cause mortality and MACEs in the high RC tertile was higher than that in the middle or low RC tertiles. In the fully-adjusted Cox regression model, the Hazard ratio(HR) [95% confidence interval (CI)] of all-cause mortality was 1.17 (1.01, 1.44) for each standard deviation(SD) increase in RC. Compared to RC tertile 1, RC tertile 3 was associated with a 94% increased risk of all-cause mortality (HR:1.94; 95%CI: 1.22–3.10). The increased risk of all-cause death from tertile 1 to tertile 3 was statistically significant. Fine-Gray test showed that regarding CV mortality, marginally statistically significant differences in cumulative incidence were observed among the three RC tertile groups ( P = 0.054). For non-CV mortality, statistically significant differences were detected across three groups ( P = 0.026). The subgroup analysis confirmed the significant association between RC and all-cause mortality. ROC curve showed that RC had a better discrimination capacity at predicting all-cause mortality (AUC (95% CI): 0.621(0.575–0.666)), and improved the prognostic value of the Gensini score combined with left ventricular ejection fraction(LVEF). Remnant cholesterol was associated with all-cause mortality in oldest-old patients with ACS in a long-term follow-up. • This is the first cohort study to explore the association between remnant cholesterol (RC) and long-term outcomes in oldest-old (≥80 years) patients with acute coronary syndrome (ACS), with a median follow-up of 51 months and a maximum duration extending up to 10 years. • Elevated RC was significantly associated with increased all-cause mortality in this population, showing a clear dose-response relationship. • RC exhibited superior discrimination capacity for predicting all-cause mortality (AUC = 0.621) compared to traditional lipid parameters (LDL-C, TC, HDL-C), with higher specificity, accuracy, and Youden's index. • Incorporating RC into the basic model (Gensini score + LVEF) significantly improved prognostic value (AUC = 0.654, P < 0.001), providing additional predictive information beyond conventional risk factors. • The association between RC and all-cause mortality remained robust in subgroup analyses and among patients with high statin use (92.90%), suggesting RC as a valuable supplement to LDL-C in prognostic evaluation for oldest-old ACS patients.