Abstract 4122948: Lipoprotein(a) associated risk of atherosclerotic cardiovascular disease is independent of C-reactive protein

Background: Elevated lipoprotein(a), present in 1 in 5 individuals, is considered a causal risk factor for atherosclerotic cardiovascular disease (ASCVD). Recent studies have reached contrasting conclusions on whether low-grade inflammation measured by elevated C-reactive protein (CRP) modifies the risk of ASCVD from high lipoprotein(a). We tested the hypothesis that high lipoprotein(a) associates with risk of recurrent ASCVD irrespective of elevated or low CRP. Additionally, we performed meta-analyses of previous studies on lipoprotein(a)-associated ASCVD risk stratified by CRP levels and by incident or recurrent events. Methods: We included 3,543 individuals with prevalent ASCVD from the Copenhagen General Population Study (CGPS), a contemporary, prospective Danish cohort study. Hazard ratios (HR) for ASCVD were examined using multivariable adjusted Cox regressions stratified by CRP (<2 mg/L and ≥2 mg/L). Random-effects meta-analyses in primary (incident events) and secondary (recurrent events) prevention were conducted separately, including studies on lipoprotein(a) and risk of ASCVD stratified by CRP. Results: During a median of 7.5 years of follow-up of 3,543 CGPS participants with established ASCVD, 1,425 experienced a recurrent ASCVD event. Multivariable adjusted HRs for ASCVD for high vs. low lipoprotein(a) were 1.41 (95% confidence interval: 1.19-1.67) and 1.31 (1.08-1.59) in individuals with low or elevated CRP with no evidence of effect modification (Figure 1A, p for interaction=0.11). When risk estimates for ASCVD were summarized in separate meta-analyses for primary and secondary prevention settings, a 50 mg/dL higher lipoprotein(a) was robustly associated with increased risk of ASCVD irrespective of CRP levels (Figure 1B). In primary prevention, a 50 mg/dL higher lipoprotein(a) associated with similar summary HRs of 1.18 (1.15-1.20) in low CRP vs. 1.16 (1.14-1.19) in elevated CRP, and likewise in secondary prevention settings, with similar HRs of 1.10 (1.07-1.14) and 1.14 (1.10-1.17), respectively. Conclusion: High lipoprotein(a) was associated with increased risk of ASCVD irrespective of CRP levels both in primary and secondary prevention settings.