High-sensitivity troponin I is one of the cardiac enzymes and has a relatively high specificity among all cardiac enzymes. If a patient is highly considered to have an acute myocardial infarction, this index will be tested. If troponin I is not tested, troponin T will also be tested because these two types of cardiac enzymes are significant and most specific for the diagnosis of myocardial infarction. If a patient presents with elevated troponin I, this is not complete proof that the patient must have had an acute myocardial infarction, but must be combined with the patient’s actual current clinical symptoms and whether the ECG has evolved dynamically. Some patients may have advanced heart failure or more severe heart failure, and may also have elevated protein I. Other patients may have severe infections or tumors and may also have elevated troponin I.