Impact of remnant cholesterol on short-term and long-term prognosis in patients with prediabetes or diabetes undergoing coronary artery bypass grafting: a large-scale cohort study

Background Remnant cholesterol (remnant-C) contributes to atherosclerotic cardiovascular disease (ASCVD), particularly in individuals with impaired glucose metabolism. Patients with impaired glucose metabolism and ASCVD remain at significant residual risk after coronary artery bypass grafting (CABG). However, the role of remnant-C in this population has not yet been investigated. Methods Adult patients with prediabetes or diabetes undergoing isolated CABG were consecutively enrolled in a longitudinal cohort between 2013 and 2018. The impact of remnant-C on short-term and long-term outcomes after CABG was evaluated. The short-term outcomes included major perioperative complications. The long-term outcomes were major adverse cardiovascular and cerebrovascular events (MACCEs). Remnant-C was analyzed as both a categorical and continuous variable. Logistic regression, Cox regression, and restricted cubic spline analyses were performed with multivariate adjustments. Results In terms of perioperative outcomes, patients with elevated remnant-C had a higher incidence of acute kidney injury (AKI) stage 2/3 (high vs. low remnant-C: 3.2% vs. 2.4%; OR: 1.404, 95% CI 1.080-1.824). Each 1-standard deviation (SD) increase in remnant-C was associated with a 16.6% higher risk of AKI stage 2/3 (OR: 1.160, 95% CI 1.067-1.260). Long-term outcomes were assessed after a median follow-up of 3.2 years, during which 1,251 patients (9.3%) experienced MACCEs. Each 1-SD increase in remnant-C was associated with a 6.6% higher risk of MACCEs (HR: 1.066, 95% CI 1.012-1.124), a 7.1% higher risk of all-cause death (HR: 1.071, 95% CI 1.008-1.209), and an 11.2% higher risk of myocardial infarction (HR: 1.112, 95% CI 1.011-1.222). These associations remained consistent when remnant-C was treated as a categorical variable. Importantly, the association between remnant-C and MACCEs was independent of LDL-C levels; higher remnant-C levels were associated with increased MACCE risk regardless of whether LDL-C was <= 2.6 mmol/L or > 2.6 mmol/L. Subgroup analysis indicated that this risk was more pronounced in insulin-treated patients. Conclusions Remnant-C is associated with AKI and MACCEs in patients with diabetes or prediabetes undergoing CABG. The MACCE risk associated with remnant-C is independent of LDL-C and is more pronounced in insulin-treated patients.