From the Guidelines
Troponin levels should be measured immediately after admission and then repeated 1 hour later in patients with suspected NSTEMI, using high-sensitivity assays, as recommended by the 2020 ESC guidelines 1. This approach allows for rapid diagnosis and risk stratification, and is supported by the most recent and highest quality evidence. The timing and pattern of troponin elevation, including a rising and/or falling pattern, are crucial in diagnosing NSTEMI, and institutions should follow their local guidelines for optimal timing of measurements. Some key points to consider include:
- Measuring cardiac troponins with high-sensitivity assays immediately after admission and obtaining the results within 60 minutes of blood sampling 1
- Using the ESC 0 h/1 h algorithm with blood sampling at 0 h and 1 h, if an hs-cTn test with a validated 0 h/1 h algorithm is available 1
- Considering additional testing after 3 hours if the first two cardiac troponin measurements of the 0 h/1 h algorithm are not conclusive and the clinical condition is still suggestive of ACS 1
- Using established risk scores for prognosis estimation, and considering the routine use of copeptin as an additional biomarker for the early rule-out of MI, where hs-cTn assays are not available 1. It is essential to note that the 2021 guidelines from the European Society of Cardiology 1 provide the most up-to-date and evidence-based recommendations for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation. Therefore, the most recent and highest quality study, the 2020 ESC guidelines, should be prioritized when making decisions about troponin trending in NSTEMI patients 1.
From the Research
Troponin Trending in NSTEMI
- The frequency of troponin trending in patients with suspected Non-ST-Elevation Myocardial Infarction (NSTEMI) is a crucial aspect of diagnosis and management.
- According to the study by 2, serial conventional cardiac troponin (cTn) measurements 6-9 hours apart are recommended for NSTEMI diagnosis.
- However, the same study suggests that 3-hour changes in troponin levels can be used to identify major adverse cardiac events (MACE) and that the addition of the HEART score can improve sensitivity.
- Another study by 3 found that a single troponin measurement can be used to exclude NSTEMI in patients with symptom duration ≥8 hours, but this approach may not be suitable for all patients.
- The study by 4 proposes a 3-hour diagnostic algorithm for NSTEMI using high-sensitivity cardiac troponin T (hs-cTnT) in unselected older patients presenting to the emergency department.
- This algorithm uses serial hs-cTnT measurements at presentation and 3 hours after presentation to rule-in or rule-out NSTEMI.
Recommendations for Troponin Trending
- Based on the available evidence, troponin levels should be measured at presentation and repeated at 3-6 hours after presentation in patients with suspected NSTEMI 2, 4.
- Small changes in troponin T levels are common in patients with NSTEMI and are linked to higher mortality, suggesting that a small change in troponin levels may not be useful to exclude NSTEMI 5.
- The use of high-sensitivity cardiac troponin assays can improve the diagnosis of NSTEMI, especially in older patients 4.
- The addition of clinical scores, such as the HEART score, can improve the sensitivity of troponin testing for NSTEMI diagnosis 2.
Clinical Considerations
- The diagnosis of NSTEMI should not be solely based on elevated troponin levels, as this can lead to expensive workup and utilization of hospital resources 6.
- Clinical presentation, ECG changes, and other diagnostic tests should be considered in conjunction with troponin levels to diagnose NSTEMI.
- The presence of chest pain, tobacco smoking, and wall motion abnormalities on echocardiogram are associated with increased risk of true ACS in patients with elevated troponins 6.