The potential impact of inflammation on the lipid paradox in patients with acute myocardial infarction: a multicenter study

Background Low-density lipoprotein cholesterol (LDL-C) is a well-recognized risk factor for cardiovascular diseases. However, several clinical studies demonstrated an inverse association between LDL-C and mortality risk in patients with acute myocardial infarction (AMI), known as the lipid paradox. This study aims to investigate the potential impact of inflammation on the association between LDL-C levels and mortality risks. Methods A total of 5244 patients with AMI from a large nationwide prospective cohort were included in our analysis. Patients were stratified according to LDL-C quartiles. The primary outcome was all-cause mortality, and the secondary endpoint was cardiac mortality. High-sensitive C-reactive protein (hsCRP) > 3 mg/L was defined as high inflammatory risk. Results During a median follow-up of 2.07 years, 297 mortality events (5.5%) and 227 cardiac mortality events (4.2%) occurred. Patients in the lowest LDL-C quartile had the highest incidence of all-cause mortality (7.3%) and cardiac mortality (5.8%). A U-shaped association between LDL-C levels and mortality risk was observed after multivariable adjustment, which persisted only in patients with high hsCRP levels. In contrast, a linear association between LDL-C and mortality risk was shown in patients with low hsCRP levels. Conclusions AMI patients with lower LDL-C levels had a higher risk of mortality. However, this association was only observed in those with high inflammatory risk. In contrast, the relationship between LDL-C and mortality risk was linear in patients with low inflammatory risk. This suggests the importance of considering inflammation when managing LDL-C levels in AMI patients.