Association of lipoprotein-associated phospholipase A₂ with coronary artery disease in African-Americans and Caucasians

Context: Lipoprotein-associated phospholipase A₂ (Lp-PLA ₂) is bound predominately to low-density lipoprotein and has been implicated as a risk factor for coronary artery disease (CAD). Objective: Weinvestigated the association between Lp-PLA₂ and CAD in a biethnic African-American and Caucasian population. Design: Lp-PLA₂ mass, activity, and index, an integrated measure of mass and activity, and other cardiovascular risk factors were determined in 224 African-Americans and 336 Caucasians undergoing coronary angiography. Main Outcome Measures: We assessed the distribution of Lp-PLA₂ levels and determined the predictive role of Lp-PLA₂ as a risk factor for CAD. Results: Levels of Lp-PLA ₂ mass and activity were highera mong Caucasians compared with African-Americans (293 ± 75 vs. 232 ± 76 ng/ml, P < 0.001 for mass and 173 ± 41 vs. 141 ± 39 nmol/min/ml, P < 0.001 for activity, respectively). However, Lp-PLA₂ index was similar in the two groups (0.61 ± 0.17 vs. 0.64 ± 0.19, P = NS). In both ethnic groups, Lp-PLA₂ activity and index was significantly higher among subjects with CAD. African-American subjects with CAD had significantly higher Lp-PLA₂ index than corresponding Caucasian subjects (0.69 ± 0.20 vs. 0.63 ± 0.18, P = 0.028). In multivariate regression analyses, after adjusting for other risk factors, Lp-PLA₂ index was independently (odds ratio 6.7, P = 0.047) associated with CAD in African-Americans but not Caucasians. Conclusions: Lp-PLA₂ activity and index was associated with presence of CAD among African-Americans and Caucasians undergoing coronary angiography. The findings suggest an independent impact of vascular inflammationamong African-Americans as contributory to CAD risk and underscore the importance of Lp-PLA₂ as a cardiovascular risk factor.