Association of LDL‐C With Angiographic Thrombus Burden in Patients With ST‐Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention

High thrombus burden (HTB) during primary percutaneous coronary intervention (PCI) for ST‐segment elevation myocardial infarction (STEMI) is associated with adverse outcomes. Low‐density lipoprotein cholesterol (LDL‐C) is a key driver of atherosclerosis, but its direct role in acute thrombus formation remains unclear. This single‐center observational study enrolled 236 consecutive STEMI patients undergoing primary PCI at our institution between November 2022 and July 2025. Thrombus burden was graded angiographically per TIMI criteria (Grades 1–3: low thrombus burden [LTB]; grades 4–5: HTB). Multivariable logistic regression evaluated associations between LDL‐C levels and thrombus burden. Restricted cubic spline (RCS) modeling explored potential nonlinear relationships. Stratified analyses assessed result robustness. HTB occurred in 78.4% (185/236) of STEMI patients receiving primary PCI. Patients with HTB demonstrated higher prior MI rates (13% vs. 2%, p = 0.024), elevated admission LDL‐C (1.8 ± 1.1 vs. 1.4 ± 0.9 mmol/L, p = 0.038), increased peak high‐sensitivity troponin T (1473.0 vs 718.0 ng/mL, p = 0.004), and longer hospitalization (6.0 ± 2.8 vs 4.9 ± 2.2 days, p = 0.007). After adjustment for age, sex, prior MI, systolic blood pressure, hemoglobin, HbA1c, and D‐dimer, each 1 mmol/L increment in admission LDL‐C was associated with a 48% increased HTB risk (adjusted OR 1.48; 95% CI 1.03–2.13, p = 0.033). Admission LDL‐C > 1.8 mmol/L predicted a 2.32‐fold higher likelihood of heavy thrombus burden (95% CI 1.04–5.18, p = 0.039). RCS analysis confirmed a linear dose–response association ( P for nonlinearity = 0.922). Sensitivity analyses using complete‐case data confirmed robustness, and subgroup analyses revealed consistent associations across age, sex, body mass index, smoking status, comorbidities, and lipoprotein(a) levels (all P for interaction > 0.05). Elevated admission LDL‐C independently correlates with HTB in primary PCI‐treated STEMI patients, suggesting LDL‐C facilitates prothrombotic pathways during acute coronary syndrome. These findings reinforce LDL‐C reduction as a therapeutic approach to mitigate thrombotic complications.