Abstract: Objective  To analyze the correlation between the degree of coronary artery disease(CAD) and low-density lipoprotein(LDL) in young and middle-aged patients with coronary heart disease(CHD).
Methods  A total of 387 patients with CHD planned to be diagnosed were included in the study. According to the imaging findings, they were divided into non-CHD group(n=124) and CHD group(n=263). The levels of total cholesterol （TC）, triacylglycerol, LDL and high-density lipoprotein(HDL) in non-CHD group and CHD group were detected. In addition, patients with CHD were divided into acute myocardial infarction group, unstable angina group and stable angina group, LDL levels were compared. Syntax score was used to evaluate the degree of CAD in CHD group, and the correlation between various biochemical indexes and syntax score was analyzed.
Results  The levels of total cholesterol, triacylglycerol, and LDL in the CHD group were higher than those in the non-CHD group, and the high-density and low-lipoprotein levels were lower than those in the non-CHD group. The difference was statistically significant(P＜0.05). The level of LDL in acute myocardial infarction group was higher than that in unstable angina group and stable angina group, the difference was statistically significant(P＜0.05). Correlation analysis results show that TC and triacylglycerol in patients with CHD are not related to the syntax score(P＞0.05); High density and low lipoprotein levels are negatively correlated with the syntax score(P＜0.05), and LDL levels are related to syntax. The score was positively correlated(P＜0.05).
Conclusion  LDL levels are closely related to the degree of CAD in young and middle-aged patients with CHD, and they are also risk factors. The increase in the level is of high value in assessing the degree of coronary artery disease.

Key words: coronary disease, lipoproteins, LDL； myocardial infarction