Cardiac Troponin I (cTnI) is the inhibitory subunit of the troponin complex, highly specific to cardiac muscle tissue and essential for regulating myocardial contraction. It is widely recognized as the "gold standard" biomarker for evaluating myocardial injury and is typically present only in trace amounts in healthy human blood. During an acute myocardial injury, such as acute myocardial infarction (AMI), cTnI is rapidly released into the bloodstream. Elevated levels can usually be detected within 2-4 hours after the onset of symptoms and peak around 12-24 hours. cTnI levels can remain elevated for 5-10 days. Compared to traditional markers like Myoglobin or CK-MB, it provides higher diagnostic sensitivity and a significantly wider monitoring window.