Lipoprotein(a) for Risk Assessment in Patients With Established Coronary Artery Disease

Objectives To assess the prognostic utility of lipoprotein (a) [Lp(a)] in individuals with coronary artery disease (CAD). Background Data regarding an association between Lp(a) and cardiovascular (CV) risk in secondary prevention populations are sparse. Methods Plasma Lp(a) was measured in 6762 subjects with CAD from three studies; data were then combined with eight previously published studies for a total of 18,979 subjects. Results Across the three studies, increasing levels of Lp(a) were not associated with the risk of CV events when modeled as a continuous variable (OR 1.03 per log-transformed SD, 95% CI 0.96-1.11) or by quintile (OR Q5:Q1 1.05, 95% CI, 0.83-1.34). When data were combined with previously published studies of Lp(a) in secondary prevention, subjects with Lp(a) levels in the highest quantile were at increased risk of CV events (OR 1.40, 95% CI 1.15-1.71), but with significant between-study heterogeneity (P=0.001). When stratified on the basis of LDL cholesterol, the association between Lp(a) and CV events was significant in studies in which average LDL cholesterol was ≥130 mg/dl (OR 1.46, 95% CI 1.23-1.73, P<0.001), whereas this relationship was not significant for studies with an average LDL cholesterol <130 mg/dl (OR 1.20, 95 CI 0.90-1.60, P=0.21). Conclusions Lp(a) is significantly associated with the risk of CV events in patients with established CAD; however, there exists marked heterogeneity across trials. In particular, the prognostic value of Lp(a) in patients with low cholesterol levels remains unclear.