Thyroid Hormone Replacement for Subclinical Hypothyroidism and Dyslipidemia in ASCVD (ThyroHeart-Lipid Study)

Inclusion Criteria: 1. Male or non-pregnant female; 2. Stable or unstable angina with evidence of myocardial ischemia; coronary angiography reveals stenosis lesions; 3. Subclinical hypothyroidism defined as mild TSH elevation within 5-10mIU/L and normal serum thyroid hormone levels within reference ranges; 4. Level of LDL-C is more than 1.8mmol/L before randomization. 5. Participate in the trial voluntarily and signs the written informed consent form. Exclusion Criteria: 1. Those who have participated in other drug or therapy equipment clinical trials but did not reach the main study endpoint time limit; 2. Symptoms of severe heart failure (NYHA Class III and above) or left ventricular ejection fraction \< 40% (ultrasound or left ventricle ngiography); 3. Pregnant or lactating women; 4. Complicated with severe organ dysfunction: large number of pericardial effusion; acute myocardial infarction; acute myocarditis; acute left heart failure; cardiogenic shock; severe arrhythmia, such as ventricular tachycardia, ventricular fibrillation, frequent atrial / ventricular premature beat, poor control of fast ventricular fibrillation, and bradycardia requiring pacemaker therapy, etc. 5. Patients who are unable to withstand lipid-lowering therapy or thyroid hormone replacement due to allergy to statins or levothyroxine; 6. Serum AST/ALT is three times higher than the upper limits of normal. 7. Patient's life expectancy is less than 12 months; 8. Those waiting for heart transplantation; 9. Patients who are deemed by the researchers to have low compliance and unable to abide by the requirements and complete the study.