Background: Whereas C-reactive protein (CRP) is a nonspecific marker of coronary artery disease (CAD) and cardiovascular (CV) events, Lp-PLA2 may be a nonvariable inflammatory biomarker. We evaluated the independent association of lipoprotein-associated phospholipase A2 (Lp-PLA2) to angiographic CAD and CV events adjusting for standard factors, lipids, and CRP.
Methods: Lipoprotein-associated phospholipase A2 (PLAC test, diaDexus, Inc, San Francisco, CA) and CRP were measured from samples donated by consecutive consenting patients (N = 1493) enrolled in the registry of the Intermountain Heart Collaborative Study. All patients underwent coronary angiography (1996-1998) for CAD determination and were followed for 6.7 +/- 0.5 years (range 5.7-7.9 years) for CV events (death [including all-cause, CAD, and non-CAD CV death], myocardial infarction, and cerebrovascular accident).
Results: Lipoprotein-associated phospholipase A2 weakly correlated with lipids (low-density lipoprotein: r = 0.22, P < .001; high-density lipoprotein: r = -0.13, P < .001), but not CRP (r = 0.03, P = .26). Increasing quartile (Q) of Lp-PLA2 predicted greater the presence of CAD (vs Q1) for Q2 (adjusted odds ratio [OR] 1.15, 95% CI 0.78-1.71, P = .48), for Q3 (OR 1.53, 95% CI 1.02-2.31, P = .042), and for Q4 (OR 2.44, 95% CI 1.58-3.79, P < .001), although CRP was also predictive (vs Q1, Q2: OR 1.47, P = .057; Q3: OR 1.93, P = .002; Q4: OR 3.43, P < .001). In Cox regression, Lp-PLA2 predicted CAD death (vs Q1; Q2: adjusted hazard ratio [HR] 1.27, 95% CI 0.58-2.78, P = .55; Q3: HR 2.18, 95% CI 1.04-4.57, P = .04; Q4: HR 1.73, 95% CI 0.84-3.61, P = .14).
Conclusion: Lipoprotein-associated phospholipase A2 was confirmed to predict the presence of CAD, even among patients undergoing coronary angiography. Uniquely, Lp-PLA2 predicted the risk of CAD death, but not all-cause death, myocardial infarction, or cerebrovascular accident.