1.Myoglobin is a good indicator for early diagnosis of myocardial infarction. It is elevated within 2 hours of onset, peaks at 12 hours, and returns to normal in 24-48 hours; 2. Troponin I (cTnI) or troponin T (cTnT): a more cardiac-specific marker, which can be elevated in 3-4 hours of onset, peaks at 11-24 hours, and returns to normal in 7-10 days, and is meaningful for early diagnosis of infarction and for patients who present late after onset; 3. Creatine kinase isoenzyme (CK-MB): high diagnostic specificity, elevated within 4 hours of onset, peaking at 16-24 hours and returning to normal in 3-4 days, its degree of elevation can more accurately reflect the extent of infarction, and whether the peak occurs earlier can help determine the success of thrombolytic therapy; 4. 5. aspartate aminotransferase (AST) is elevated after 6-12 hours of onset, peaks at 24-48 hours, and decreases to normal in 3-6 days; 6. lactate dehydrogenase (LDH): slightly less sensitive, elevated after 8-10 hours of onset, peaks in 2-3 days, and lasts 1 to 2 weeks before returning to normal. Myoglobin appears earliest, with strong sensitivity and poor specificity; troponin appears later, with strong specificity and long duration, and CK-MB is less sensitive than troponin, which has important value for early diagnosis.