M Al Rifai, SS Martin, JW McEvoy, K Nasir, R Blankstein, J Yeboah, M Miedema, SJ Shea, JF Polak, P Ouyang, RS Blumenthal, M Bittencourt, I Bensenor, RD Santos, BB Duncan, IS Santos, PA Lotufo and MJ Blaha,
Atherosclerosis, Jul 2018
The prevalence and correlates of subclinical atherosclerosis when low-density lipoprotein cholesterol (LDL-C) levels are low remain unclear. Therefore, we examined the association of cardiovascular risk factors and subclinical atherosclerosis among individuals with untreated LDL-C <70 mg/dL.We included participants from the Multi-Ethnic Study of Atherosclerosis (MESA) and the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) cohorts. To optimize accuracy, LDL-C was calculated by the validated Martin/Hopkins equation that uses an adjustable factor for the ratio of triglycerides to very low-density lipoprotein cholesterol. We defined subclinical atherosclerosis as a coronary artery calcium (CAC) score >0 in the combined cohort or common carotid intima media thickness (cIMT) in the 4th quartile, using cohort-specific cIMT distributions at baseline. Logistic regression models examined the cross-sectional associations of cardiovascular risk factors and subclinical atherosclerosis.Among 9411 participants not on lipid lowering therapy, 263 (3%) had LDL-C <70 mg/dL (MESA: 206, ELSA: 57). Mean age in this population was 58 (SD 12) years, with 43% men, and 41% Black. The prevalence of CAC >0 in those with untreated LDL-C<70 mg/dL was 30%, and 18% were in 4th quartile of cIMT. In demographically adjusted models, only ever smoking was significantly associated with both CAC and cIMT. Similar results were obtained in risk factor-adjusted models (smoking: OR, 2.29; 95% CI, 1.10-4.80 and OR, 3.44; 95% CI, 1.41-8.37 for CAC and cIMT, respectively).Among middle-aged to older individuals with untreated LDL-C <70 mg/dL, subclinical atherosclerosis remains moderately common and is associated with cigarette smoking.