Cardiac Medicine Certification (CMC) Practice Exam

What does a prolonged elevated troponin level indicate post-myocardial infarction?

1. Transient ischemia

2. Stable angina

3. Extended myocardial injury

4. Routine laboratory error

The correct answer is: Extended myocardial injury

A prolonged elevated troponin level following a myocardial infarction indicates extended myocardial injury. Troponin is a protein released into the bloodstream when the heart muscle is damaged, and its elevation is a critical marker for the diagnosis of myocardial infarction. After the initial injury that occurs during the infarct, troponin levels typically rise within a few hours, peak within 24-48 hours, and then gradually decline. However, if troponin levels remain elevated beyond the expected timeframe, it suggests that there is ongoing or extended injury to the myocardial tissue, potentially due to complications such as reperfusion injury, additional ischemic episodes, or cardiac strain. This prolonged elevation indicates that the heart muscle is continuing to suffer damage or stress, as opposed to transient ischemia, which would typically result in temporary troponin elevations that normalize once blood flow returns to normal. Similarly, stable angina is characterized by episodes of chest pain related to a predictable level of activity without resulting in significant myocardial injury or prolonged troponin elevation. Lastly, while laboratory errors can occasionally cause discrepancies in troponin levels, a consistent and prolonged elevation in the context of a myocardial infarction is far more indicative of continued myocardial pathophysiology rather than a routine error.