Plasma Lipoprotein(a) Level Associated With Coronary Heart Disease And Severity Of Coronary Artery Atherosclerosis

Objective: (1) To investigate the association between plasma lipoprotein(a) level and severity of coronary artery atherosclerosis. (2) To determine the eligible range of normal plasma lipoprotein(a) level, for directing preservation of coronary heart disease.Method: 101 patients who underwent elective coronary angiography were studied. According to the numbers and extents of coronary artery with stenosis, four groups were classified: 0-vessel group for no stenosis; premature group for coronary lesion with diameter stenosis less than 50%; 1-vessel group for one artery with diameter stenosis more than 50%; multiple-vessel group for two or more coronary artery with diameter stenosis more than 50%. The severity of coronary atherosclerosis were evaluated according to stenosis score for main vessels(LAD , LCX, RCA and LMC): 0 for no stenosis; 1 for coronary lesion with diameter stenosis from 1% to 24%; 2 for 25%-49%; 3 for 50%-74%; 4 for 75%-99% and 5 for complete stenosis. Stenosis in LMC would be considered as involving both LAD and LCX. Score of each stenosis artery contributed to total score. Cholesterol and triglyceride concentrations were determined enzymatically on a 7170A chemistry autoanalyzer. HDL was measured enzymatically in the supernate after precipitation of other lipoproteins. LDL was calculated by using the Friedewald formula. ApoB-100, ApoA-I and Lp(a) were measured by immunoturbidimetry using reagents from Leadman.Result: (1) The median of plasma lipoprotein(a) level in CHD group was obviously higher than that in group without CHD (Z=-4.404,P<0.01).There was significant difference among the four groups(X2=22. 03, P<0.01). Multiple-vessel group has distinctly higher concentration of lipoprotein(a) than 0-vessel group(P<0.01) and premature group(P<0.05). The level of lipoprotein(a) in one-vessel group was higher than that hi 0-vessel group. The difference between multiple-vessel group and 0-vessel group existed in both male and female. (2) Plasma lipoprotein(a) concentration was elevated in postmenopause female, compared with that in premenopause female. (3) Stepwise multiple linear regression was used to examine the relation of independent(Lp(a) and lipid indexes) and dependent(stenosis score). In multiple regression analysis, an equation was established as y=3.913+0.134xi+ 2.116x2-2.654x3-2.882x4, (x1, x2, x3, X4 were LP(a), LDL, HDL, ApoA-I , respective). Their standard partial regression coefficients were respectively as 0.441 (t =6.132, P<0.001) , 0.399(1=5.536, P<0.001),-0.223(t=-3.161, P=0.002), -0.159(t=-2.261, P=0.026). (4) In ROC curve analysis, the sum of sensitivity and specificity was largest when the value of Lp(a) was 12.05mg/dl. The area under the curve was 0.759(P<0.001).Conclusion: (1) Elevated plasma lipoprotein(a) level play an important role in progression of CHD, is an independent risk factor for CHD. And there was a positive correlation between plasma lipoprotein(a) level and severity of coronary atherosclerosis. This correlation existed in both male and female. (2) Plasma lipoprotein(a) concentration was hormonally regulated. (3) The proper range of plasma lipoprotein(a) level was suggested to 0~ 12.05mg/dl.