BMI modifies HDL-C effects on coronary artery bypass grafting outcomes

Background Despite the recognized implications of high-density lipoprotein cholesterol (HDL-C) in cardiovascular diseases, the role of body mass index (BMI) in HDL-C association with cardiovascular outcomes remains unclear. This study investigated the possible modifying implications of BMI on the correlation between HDL-C and coronary artery bypass grafting (CABG) outcomes. Methods The present cohort included isolated CABG patients (median follow-up: 76.58 [75.79-77.38] months). The participants were classified into three groups: 18.5 [less than or equai to] BMI < 25 (normal), 25 [less than or equai to] BMI < 30 (overweight), and 30 [less than or equai to] BMI < 35 (obese) kg/m.sup.2. Cox proportional hazard models (CPHs) and restricted cubic splines (RCSs) were applied to evaluate the relationship between HDL-C and all-cause mortality as well as major adverse cardio-cerebrovascular events (MACCEs) in different BMI categories. Results This study enrolled a total of 15,639 patients. Considering the final Cox analysis among the normal and overweight groups, HDL-C [greater than or equal to] 60 was a significant protective factor compared to 40 < HDL-C < 60 for all-cause mortality (adjusted hazard ratio (aHR): 0.47, P: 0.027; and aHR: 0.64, P: 0.007, respectively). However, the protective effect of HDL-C [greater than or equal to] 60 was no longer observed among patients with 30 [less than or equai to] BMI < 35 (aHR: 1.16, P = 0.668). RCS trend analyses recapitulated these findings; among 30 [less than or equai to] BMI < 35, no uniform inverse linear association was observed; after approximately HDL-C[appox. equal to]55, its increase was no longer associated with reduced mortality risk. RCS analyses on MACCE revealed a plateau effect followed by a modest rise in overweight and obese patients from HDL-C = 40 onward (nonlinear association). Conclusions Very high HDL-C ([greater than or equal to] 60 mg/dL) was not related to better outcomes among obese CABG patients. Furthermore, HDL-C was related to the post-CABG outcomes in a nonlinear manner, and the magnitude of its effects also differed across BMI subgroups. Keywords: HDL-C, BMI, CABG, Outcome, Nonlinear relationship