From the Guidelines
Troponin levels should be measured at presentation, then 3-6 hours later, with a third measurement at 6-12 hours if clinical suspicion remains high despite normal initial values, as recommended by the 2014 AHA/ACC guideline for the management of patients with non-ST-elevation acute coronary syndromes 1.
Key Considerations for Troponin Monitoring
- The goal of serial troponin measurements is to identify a rising and/or falling pattern, which is essential for the diagnosis of acute myocardial infarction, as stated in the universal definition of myocardial infarction 2.
- Troponin levels typically begin to rise 3-4 hours after myocardial injury, peak at 24-48 hours, and may remain elevated for 5-14 days.
- Chronic conditions like renal failure or heart failure can cause persistent troponin elevations, so the absolute change in values over time is more diagnostically important than a single elevated result.
Discontinuation of Troponin Monitoring
- Testing can be stopped when either a diagnosis of myocardial infarction is confirmed (with a significant rise and/or fall in troponin levels above the 99th percentile upper reference limit), or when at least two sequential measurements 3-6 hours apart show no significant change and remain below the diagnostic threshold.
- For patients with confirmed myocardial infarction, additional troponin measurements beyond diagnosis provide little clinical value unless there is concern for reinfarction.
Special Considerations
- High-sensitivity troponin assays may allow for earlier decision-making, with some protocols using 0 and 1-2 hour measurements.
- The use of assays that do not have independent validation of optimal precision (CV10%) is not recommended, as stated in the universal definition of myocardial infarction 2.
From the Research
Trending Troponin Levels
- Troponin levels can be trended by obtaining serial measurements, with the frequency and timing of measurements depending on the patient's clinical presentation and risk stratification 3, 4, 5.
- The HEART score is a clinical decision support tool that includes troponin level as one of its elements, and serial troponin measurements can provide additional information for risk stratification 3, 5.
- Studies have shown that serial troponin measurements can help identify patients at risk for short- and long-term outcomes, particularly in those with acute heart failure or chest pain 4, 6.
Determining When to Discontinue Monitoring
- The decision to discontinue troponin monitoring should be based on the patient's clinical presentation, risk stratification, and the results of serial troponin measurements 3, 5.
- For patients with a low-risk HEART score, serial troponin measurements may provide limited added benefit, and monitoring can be discontinued after a negative initial measurement 3.
- In contrast, patients with a moderate- or high-risk HEART score, or those with acute heart failure, may require ongoing troponin monitoring to assess their risk for adverse outcomes 4, 7.
- A single high baseline troponin measurement can be used to rule in acute myocardial infarction, while serial measurements can be used to rule out acute myocardial infarction 6.
Key Considerations
- The timing and frequency of troponin measurements should be individualized based on the patient's clinical presentation and risk stratification 3, 4, 5.
- Serial troponin measurements should be interpreted in the context of the patient's overall clinical picture, including their symptoms, electrocardiogram results, and other diagnostic tests 3, 4, 7.
- The use of high-sensitivity troponin assays can provide more accurate and reliable results, particularly in patients with acute myocardial infarction or acute heart failure 4, 6.