Preoperative lipid concentrations and 28-day mortality after cardiac surgery with cardiopulmonary bypass: a retrospective analysis of a prospectively maintained registry

BACKGROUND: Low cholesterol is associated with poor outcomes in acute illness, although low LDL-Cholesterol (LDL-C) is a therapeutic target in cardiovascular disease. We assessed whether preoperative lipid concentrations were associated with 28-day mortality after cardiac surgery with Cardiopulmonary Bypass (CPB). METHODS: We retrospectively analysed a prospectively maintained single-centre registry of cardiac surgery with CPB (April 2013-December 2023), linked to preoperative lipid measurements and national death records. LDL-C was the primary exposure. Models were adjusted for EuroSCORE 2, statin use, infective endocarditis, urgent surgery, and critical preoperative state. Secondary analyses were corrected for multiplicity (Benjamini-Hochberg). RESULTS: Of 10,088 patients, 71 were excluded (reoperation within one year or duplicate record) and 1,986 of the remaining 10,017 had a preoperative lipid panel; 64 (3.2%) died within 28-days. In unadjusted analyses, lower Total Cholesterol (TC), HDL-C and LDL-C were associated with mortality. After adjustment, LDL-C was no longer associated with mortality (adjusted odds ratio = 0.803, 95% CI 0.595-1.084; p = 0.152). TC retained a borderline association (0.777, 0.607-0.994; p = 0.045), not surviving correction (q = 0.173). Lipid parameters discriminated poorly (areas under the curve 0.57-0.62) and added nothing to EuroSCORE 2. CONCLUSIONS: After adjustment for illness severity, preoperative LDL-C was not associated with 28-day mortality, and lipids provided no prognostic information beyond EuroSCORE 2. Very low TC may primarily reflect illness severity rather than an independent causal risk factor, and these data provide no basis for modifying perioperative lipid-lowering therapy.