In a patient with acute coronary syndrome, which biomarker is most specific for myocardial necrosis?

Troponin I is the biomarker that is most specific for myocardial necrosis in the context of acute coronary syndrome. It is a protein found in cardiac muscle that is released into the bloodstream when there is damage to the heart muscle, such as in myocardial infarction. The specificity of troponin I is attributed to its structure and its presence primarily in cardiac tissue, which makes it a more accurate indicator of heart injury compared to other biomarkers.

While other markers like creatine kinase (CK) and its isoenzyme CK-MB do indicate myocardial injury, they are less specific because CK can be elevated in conditions affecting skeletal muscle or other tissues, leading to potential false positives. Myoglobin, on the other hand, is a non-specific marker that can be elevated in a variety of conditions, including skeletal muscle injury, and does not provide the same specificity for cardiac events.

In summary, the reason troponin I is preferred in diagnosing myocardial necrosis in acute coronary syndrome is due to its high specificity for cardiac tissue, making it the most reliable biomarker for assessing myocardial injury.