Premature coronary heart disease (CHD) refers to the onset of myocardial infarction in men < 55 years old, women < 65 years old. At present, researches on early-onset coronary heart disease mostly focus on its risk factors and clinical characteristics, but there is no relevant research on the relationship between early-onset myocardial infarction and atherosclerosis.

Premature coronary heart disease is defined as the first onset of male < 55 years old, female < 65 years old, confirmed by clinical examination. A number of studies have found that smokers have a significantly increased risk of acute myocardial infarction, and suggest that continued smoking is still an independent predictor of mace. These findings suggest that smoking is significantly associated with early-onset coronary heart disease. A number of studies have found that smoking can increase peripheral arterial stiffness. At present, there is no study on peripheral arterial stiffness in patients with early-onset myocardial infarction, so we suspect that peripheral arterial stiffness in patients with early-onset myocardial infarction is significantly increased

Inclusion Criteria:

• The onset of coronary heart disease (including acute coronary syndrome and stable angina pectoris) was less than 55 years old in men and 65 years in women

Exclusion Criteria:

• Non coronary heart disease leading to chest pain (myocarditis, pericarditis, pulmonary embolism, aortic dissection, unstable angina pectoris) definite infection tumor liver and kidney insufficiency autoimmune disease acromegaly hyperthyroidism and subclinical hyperthyroidism secondary hypertension, etc.

Patients with primary coronary heart disease were male < 55 years old and female < 65 years old