Abstract 366: Gender Differences Exist in Carotid Arterial Plaque Composition Among Men and Women with Carotid or Coronary Artery Disease and Elevated ApoB Levels

Abstract

Introduction: Postmortem coronary artery histopathology and post-surgical carotid endarterectomy studies demonstrate that women have less calcification and inflammatory cells, but more smooth muscle cells than men. Gender differences in atherosclerotic plaque composition are not well known. Yet, the age-adjusted incidence of stroke and myocardial infarction are higher in men than women. Hypothesis: We hypothesized that gender differences exist in carotid plaque composition (CPC), % lipid rich necrotic core (LRNC) and % wall volume (PWV), comparing living women and men. Methods: The CPC study is a prospective, randomized study evaluating the effect of 1) atorvastatin + placebo + placebo vs 2) atorvastatin + niacin ER + placebo 3) atorvastatin + niacin ER + colsevelam on CPC. Participants had coronary or carotid artery disease and ApoB levels ≥120 mg/dL. CPC was evaluated using MRI. Baseline PWV [(wall volume/total vessel volume) х 100%], a measure of plaque burden that adjusts for variation in artery size, and % LRNC volume (among slices with LRNC present) were evaluated. Statistical analysis used Wilcoxon rank sum test, chi-square, and multivariate linear regression. Results: There were 82 women and 118 men. Women vs. men were older, mean±SD age 58±8 vs. 55±8 yrs. (p=0.008), had higher HDL-C, 48±13 vs. 40±10 mg/dL (p<0.001), higher ApoA1 147±24 vs. 126±19 mg/dL (p<0.001), higher ApoE 5.5±3.4 vs. 4.5±1.6 mg/dL (p=0.04), lower % of prior myocardial infarction 22% vs. 52% (p=0.02) and higher % of metabolic syndrome 48% vs. 46% (p=0.01). There were no significant differences in ApoB levels, 123±32 vs. 120±29 (p=0.4). After adjusting for age, HDL-C (strongly correlated with ApoA1, r=0.89), ApoE, prevalence of myocardial infarction and metabolic syndrome, the men-women difference in PWV was small and statistically non-significant ([[Unable to Display Character: ∆]] 0.0%, 95% CI -2.5 to 2.6%, p=1.0). However, among participants with LRNC, men had more % LRNC than women ([[Unable to Display Character: ∆]] 5.9%, 95% CI 1.4 to 10.3%, p=0.01) after the same adjustments. Conclusions: Gender differences exist in CPC in that there is a higher volume of LRNC in men compared to women. Further studies are needed which delineate the mechanisms underlying the differences in prevalence of LRNC comparing men to women.