Abstract P270: Associations of Lipoprotein-associated Phospholipase A2 Mass and Activity with Coronary Artery Calcium: The Multi-Ethnic Study of Atherosclerosis (MESA)
Background: Lipoprotein-associated phospholipase A2 (Lp-PLA2) is an inflammatory enzyme localized in atherosclerotic lesions. However, associations of Lp-PLA2 with coronary artery calcium (CAC), used as a marker of lesion progression, have not been extensively studied and may vary by sex and type of Lp-PLA2 assay.
Methods: We examined these associations in 5486 White, Black, Chinese and Hispanic men and women in the Multi-Ethnic Study of Atherosclerosis (MESA). At baseline, mean age was 62 years; all were free of clinical cardiovascular disease. CAC, by cardiac computed tomography, was assessed at baseline (2000-02) and follow-up; half the cohort at exam 2 (2002-04), the remainder at exam 3 (2004-05). 2758 had CAC (Agatston score>0) at baseline; of those with no baseline CAC, 372 (13.6%) had incident CAC (CAC>0) at follow-up. Lp-PLA2 mass and activity were measured by immunoassay and enzymatic assay, respectively. Longitudinal models were adjusted for age, sex, ethnicity, smoking, diabetes, obesity, total and HDL cholesterol, blood pressure, hypertension, lipid-lowering medications and time between CAC measures.
Results: Each standard deviation (SD 36.5 nmol/min/ml) increase in Lp-PLA2 activity was associated with CAC presence (prevalence ratio 1.03; p=0.01) in the whole group at baseline and incidence in those with no CAC at baseline (odds ratio 1.17; p=0.02). Activity was not associated with CAC progression (increase in Agatston score over time) in the whole group (β=1.32; p>0.4). Lp-PLA2 mass was not associated with CAC presence or incidence (SD 45.6 ng/ml; associations p>0.2). The only association that differed significantly by sex was that for mass and progression (p interaction 0.01). Mass was associated with CAC progression in women (β=4.99; p=0.004) but not men (β=-0.20; p>0.9).
Conclusions: In this multi-ethnic cohort, associations of Lp-PLA2 with CAC varied by sex and Lp-PLA2 assay type. Lp-PLA2 activity was associated with CAC presence and incidence, but not progression. Mass was associated with CAC progression in women only. Additional research is needed to support the clinical utility of Lp-PLA2 in monitoring atherosclerosis progression.
- © 2013 by American Heart Association, Inc.