Low density lipoprotein cholesterol and cardiovascular disease risk in patients with absence of coronary artery calcification: a multicenter cohort study

Abstract Background Low-density lipoprotein cholesterol (LDL-C) plays a central role in the development of coronary heart disease (CHD). Absence of coronary artery calcification (CAC 0), as assessed by coronary computed tomography angiography (CCTA), is associated with a favorable outcome as it indicates a low burden of atherosclerosis. However, questions remain regarding the risk of non-calcified plaque and CHD in younger patients with CAC zero, as atherosclerosis tends to be non-calcified in earlier stages. Purpose To assess if LDL-C is associated with presence of non-calcified plaque and future cardiovascular events in patients with CAC zero across the age spectrum. Methods This observational multicenter cohort study included patients aged 18 years or more who underwent CCTA between January 2008 and May 2021 with CAC zero. LDL-C was measured prior to CCTA. Patients were followed from date of CCTA to occurrence of cardiovascular event, death, or 1st of October 2022. No patients were lost to follow-up. We assessed the association between LDL-C and presence of non-calcified plaque on CCTA as adjusted odds ratios, and risk for myocardial infarction and CHD (myocardial infarction or coronary revascularization) as adjusted hazard ratios using Cox regression analyses, across different age groups. Results A total of 23,776 patients with CAC zero were included in the study. Median age was 54 years (IQR 47-61) and 14,605 (61%) were women. During median follow-up of 5.5 years, 165 (0.7%) and 427 (1.8%) experienced myocardial infarction and CHD, respectively. Overall, the prevalence of non-calcified plaque was 11.1% (n=2,650). Higher LDL-C was associated with presence of non-calcified plaque with an odds ratio of 1.21 (95% CI 1.16-1.27) per 1 mmol/L higher LDL-C. Individuals aged ≤45 years had a higher odds ratio for non-calcified plaque per 1 mmol/L higher LDL-C compared to individuals aged 46-60 and >60 years; 1.36 (95% CI 1.22-1.52), 1.22 (95% CI 1.15-1.30) and 1.13 (95% CI 1.04-1.22), respectively, p value for interaction between the youngest and oldest age group was <0.05. Overall, LDL-C was associated with higher risk for myocardial infarction and CHD with hazard ratios of 1.29 (95% CI 1.10-1.52) and 1.26 (95% CI 1.14-1.39) per 1 mmol/L higher LDL-C, despite CAC zero. Conclusions Particularly in younger patients with absence of CAC, elevated LDL-C is associated with presence of non-calcified plaque and increased risk for future cardiovascular events. These data are important for clinical practice, as they demonstrate the importance of managing LDL-C in younger individuals over the long-time horizon despite CAC zero.