Study of Risk Factors in Patients with Angiographically Defined Coronary Atherosclerosis : With Special References to Metabolic Factors

Several main risk factors of coronary artery disease (CAD) were studied in consecutive 200 subjects undergoing coronary angiography. Especially, in order to examine the effect of disturbance of glucose and lipid metabolism on the progression of CAD, glucose tolerance test was carried out and the levels of serum lipids and apoproteins were measured in 90 cases selected at random from 200 subjects. Results were compared between the patients with CAD (n=51) and normal controls (n=39). The following results were obtained. 1) The incidence of diabetes mellitus (DM) was 24% in CAD group and was 3.1 times higher than that of control group. The prevalence of abnormal glucose tolerance (AGT) which include both DM and impaired glucose tolerance (IGT) was 48% in CAD group and was 2.7 times higher than that of control group. These high incidence showed that some factors derived from disturbed glucose metabolism must play an important role for the progression of CAD. 2) Low levels of HDL-cholesterol (43.2±1.7mg/dl) and high values of atherogenic index (4.9±0.3) in CAD group were most important risk factors in the study of serum lipid. Furthermore, these results were independently different in CAD group with or without AGT compared to control group statistically (p<0.025-0.02). 3) In the study of apoprotein (A-I, A-II, B, C-II, E), low apo A-I value was noted significantly in CAD group (115.7±3.0mg/dl) compared to control group (132.2±4.0mg/dl) (p<0.005). It has been reported that slightly higher apo A-I levels were observed in diabetics. Therefore, low apo A-I value was indicated to be an important discriminator for the coronary atherosclerosis in CAD group with AGT. Apo C-II and apo E levels were significantly higher (p<0.0025-0.001) in CAD group with AGT, which might indicate the abnormal metabolism of triglyceride rich lipoprotein induced by abnormal glucose tolerance. 4) Although blood glucose levels were not different significantly between CAD and control groups, hypersecretion of insulin was detected in CAD group (p<0.05). In order to clarify the reason of hyperinsulin response during glucose loading, erythrocytes insulin receptors were measured. Insulin binding to erythrocytes was not different in both groups. In conclusion, these results clarified the role of abnormal glucose and lipid metabolism for the progression of CAD.