In a patient experiencing chest pain, which cardiac biomarker is most specific for myocardial infarction?

Troponin I is the most specific cardiac biomarker for myocardial infarction. In cases of myocardial injury, specifically myocardial infarction, troponins (including both troponin I and troponin T) are released into the bloodstream as a result of damage to cardiac myocytes. Compared to other cardiac biomarkers, troponins are more specific to heart muscle damage because they are integral components of the cardiac muscle contractile apparatus.

While creatine kinase (CK), particularly CK-MB, is also used to assess cardiac injury, it is not as specific for myocardial infarction as troponin I, as CK can also be elevated in other conditions such as skeletal muscle injury. Myoglobin, though it is one of the earliest biomarkers to rise after myocardial injury, lacks specificity because it is released from both cardiac and skeletal muscle, making it less reliable for diagnosing myocardial infarction. B-type natriuretic peptide (BNP) is primarily a marker for heart failure and is not used to diagnose myocardial infarction. Thus, troponin I stands out as the most specific indicator for myocardial infarction diagnosis, enabling clinicians to distinguish myocardial damage from other potential causes of chest pain.