LYSINE-BINDING SPECIES OF LIPOPROTEIN(A) IN CORONARY-ARTERY DISEASE

Elevated levels of plasma lipoprotein(a) [Lp(a)] have frequently been associated with coronary artery disease (CAD). Recently Lp(a) was frac tionated into two species with different affinities for Lysine-Sepharo se. The influence of lysine-binding heterogeneity of Lp(a) on its card iovascular pathogenicity has not previously been studied. The authors have determined plasma levels of total Lp(a), its lysine-binding [lys] and unretained [lys-] species in 67 male CAD patients undergoing car diac catheterization. Forty-three patients have severe CAD (two- or th ree-vessel disease) and 24 patients have less pronounced CAD (one-vess el disease or less than 50% narrowing of coronary vessels). All patien ts were ranked in order of their Lp(a) levels and then grouped into qu artiles. The prevalence of severe CAD was significantly higher in the upper Lp(a) quartile as compared with the other three quartiles (odds ratio 105; chi-square 11.2; P=0.0008). Similar results were obtained w hen the same analysis was carried out for [lys+] and [lys-] species of Lp(a) (odds ratio 11.52 and 3.3, respectively; chi-squre 12.3 and 4.3 4, respectively; P=0.0004 and 0.037, respectively). Thus, measurement of either species of Lp(a) does not provide any additional improvement in the prediction of CAD as compared to the estimation of total Lp(a) levels.