Acute myocardial infarction ( acute myocardial infarction , AMI ) is a common acute and frequent clinical disease, correct diagnosis and timely treatment is important to save dying myocardium, to reduce the acute stage of the morbidity and mortality rate. Troponin is a regulatory protein on myofibers in cardiomyocytes and consists of 3 subunits (cTnI, cTnT, cTnC). Troponin I is a regulatory protein secreted by cardiomyocytes and is localized in fast skeletal muscle, slow muscle and cardiac muscle, respectively. When myocardial injury occurs, cardiomyocytes can continuously secrete cTnI and enter the circulation, resulting in a rapid increase of cTnI levels in the blood. Serum cTnI concentration shows a bimodal change, and the diagnostic time window is up to several weeks, which is wider than that of creatine kinase isoenzyme MB (CK-MB), and the sensitivity is higher than that of CK-MB. It is gradually replacing CK-MB as the “gold standard” for determining myocardial injury, especially AMI.

The sensitivity of cTnI, cTnT, CK and CK-MB as indicators of thrombolytic efficacy was 95%, 80%, 54% and 56%, respectively, and the specificity was 100%, 89%, 79% and 82%, respectively. cTnI has a high clinical value in evaluating thrombolytic efficacy.

cTnI is valuable in evaluating the outcome of viral myocarditis, which helps to guide treatment and stop the development of cardiomyopathy after myocarditis. The sensitivity and specificity of measuring cTnI to reflect myocardial injury has been used as one of the important bases for the diagnosis of myocarditis.

Some patients with heart failure have elevated cTnI in serum, and their cardiac function and prognosis are significantly worse than those of patients with normal cTnI, but with the improvement of the condition, the cTnI in serum returned to normal level. cTnI is closely related to the severity and outcome of heart failure, and it has certain clinical value for the diagnosis of heart failure.

The degree of necrosis of cardiomyocytes is an important indicator for determining their near-term mortality, and cTnI has high clinical value for the near-term risk stratification of ACS.

cTnI is highly sensitive and specific in diagnosing perioperative AMI. During aortic valve replacement, aortic cross-clamp time was highly correlated with cTnI values, suggesting that cTnI is a reliable indicator of ischemia during cardiac surgery and can be used as a protective measure in the evaluation of cardiac function.