Which cardiac enzyme remains elevated the longest following an acute myocardial infarction?

Cardiac troponins are proteins found in heart muscle that play a crucial role in muscle contraction. Following an acute myocardial infarction (AMI), or heart attack, troponins are released into the bloodstream as cardiac muscle cells are damaged.

One key reason why cardiac troponins remain elevated in the blood longer than other cardiac markers is their slow clearance from circulation. Troponins can be detected for up to one to two weeks post-infarction, making them highly sensitive and specific indicators of myocardial injury. Their prolonged elevation is particularly useful for clinicians in diagnosing recent AMIs, even several days after the event.

In contrast, other markers like CK-MB and myoglobin have shorter half-lives and peak earlier after myocardial injury. CK-MB typically elevates and then returns to baseline levels within a few days, while myoglobin, which can also rise quickly, has a short window of detection due to its rapid clearance from the bloodstream. Hence, while these markers can indicate muscle damage and are useful in different contexts, cardiac troponins provide a longer detection window, which is critical in a clinical setting for timely and effective patient management.