Evaluation of Lipoprotein(a) Electrophoretic and Immunoassay Methods in Discriminating Risk of Calcific Aortic Valve Disease and Incident Coronary Heart Disease: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND A number of lipoprotein(a) [Lp(a)] analytical techniques are available that quantify distinct particle components, yet their clinical efficacy has not been comprehensively evaluated. This study determined whether Lp(a) mass [Lp(a)-M], Lp(a) cholesterol content [Lp(a)-C], and particle concentration [Lp(a)-P] differentially discriminated risk of calcific aortic valve disease (CAVD) or incident coronary heart disease (CHD) among 4679 participants of the Multi-Ethnic Study of Atherosclerosis (MESA). METHODS Lp(a)-M, Lp(a)-C, and Lp(a)-P were measured in individuals without clinical evidence of CHD at baseline. Relative risk regression and Cox proportional analysis determined associations between Lp(a) and the presence of CAVD or 12-year risk of CHD, respectively. To control for the relatively high lower limits of quantification for Lp(a)-C and Lp(a)-P assays, the upper 25th and 15th percentiles were selected as analytical cutoff points. RESULTS Regardless of method or analytical cutoff, high Lp(a) concentrations were significantly associated with CAVD and CHD in MESA participants following adjustment for typical cardiovascular risk factors. Stratifying by race/ethnicity rendered most associations nonsignificant after correction for multiple comparisons, but Lp(a) remained associated with CAVD in whites irrespective of method (all P < 0.0001). CONCLUSIONS Associations of Lp(a)-C, Lp(a)-P, and Lp(a)-M with CAVD or incident CHD were similar in this entire MESA sample using a dichotomized statistical approach. However, the high lower limits of quantification and imprecision of the Lp(a)-C and Lp(a)-P assays limited their usefulness in our analyses and would likely do so in research and clinical settings.