Why is troponin I used as a cardiac marker?

Troponin I is a protein that is found in the heart muscle. It is one of the three subunits of the troponin complex, which is responsible for regulating muscle contraction. When the heart is damaged, troponin I is released into the bloodstream. This can be detected by a blood test, which can help to diagnose a heart attack or other forms of heart damage.

Troponin I is a more specific cardiac marker than other proteins, such as creatine kinase (CK) and myoglobin. This means that it is less likely to be elevated in other conditions, such as skeletal muscle damage. Troponin I levels also remain elevated for a longer period of time than CK and myoglobin, which can be helpful for diagnosing a heart attack that occurred several hours ago.

The American College of Cardiology (ACC) and the American Heart Association (AHA) recommend using troponin I as the preferred cardiac marker for diagnosing heart attacks. This is because troponin I is more sensitive and specific than other cardiac markers, and it can help to diagnose heart attacks that occur several hours ago.