Estimated small dense low-density lipoprotein cholesterol and incident myocardial infarction in patients undergoing dialysis: a nationwide cohort study

Background Small dense low-density lipoprotein cholesterol (sdLDL-C) is an atherogenic LDL subfraction that may reflect lipid-related coronary risk beyond conventional cholesterol levels. Estimated sdLDL-C (E-sdLDL-C) is calculated from a standard lipid panel, but its prognostic relevance for myocardial infarction in patients undergoing dialysis remains uncertain.Methods This nationwide cohort study included 21,671 adults with end-stage kidney disease (ESKD) receiving long-term dialysis who underwent health screening in 2009–2017. E-sdLDL-C was calculated from fasting lipid profiles and categorised into quartiles. Incident myocardial infarction and ischemic stroke were the primary and secondary outcomes, respectively, assessed through December 2022.Results During 166,428 person-years, 993 myocardial infarctions occurred, with 9,426 deaths before myocardial infarction. Fully adjusted hazard ratios for myocardial infarction in Quartiles 2–4 versus Quartile 1 were 1.24 (95% CI, 1.01–1.52), 1.61 (1.32–1.96), and 1.44 (1.15–1.80), respectively. The association remained significant after accounting for competing mortality. For ischemic stroke, 1,249 events and 9,254 competing deaths occurred during 165,727 person-years, with no significant association with E-sdLDL-C after full adjustment. Adding E-sdLDL-C increased the C-index for myocardial infarction from 0.716 to 0.726 (Δ = 0.010), without significant differences from models including LDL-C (0.725; p = 0.453) or non-HDL-C (0.727; p = 0.264).Conclusion Among patients undergoing long-term dialysis, E-sdLDL-C was associated with incident myocardial infarction after multivariable adjustment, whereas no significant association was observed with ischemic stroke. These findings support the potential relevance of E-sdLDL-C for myocardial infarction risk assessment in patients with ESKD, although its clinical utility requires further validation.