From the Guidelines
The best interval for checking troponins is typically at presentation (baseline), 3 hours, and 6 hours after symptom onset in patients with suspected acute coronary syndrome. This recommendation is based on the highest quality and most recent evidence available, specifically the 2017 AHA/ACC clinical performance and quality measures for adults with ST-elevation and non-ST-elevation myocardial infarction 1. The guidelines suggest that serial cardiac troponin I or T levels should be obtained at presentation and 3 to 6 hours after symptom onset to identify a rising and/or falling pattern of values.
Key Considerations
- The timing of troponin checks is critical because troponin levels begin to rise 3-4 hours after myocardial injury, peak at 24-48 hours, and may remain elevated for 7-14 days.
- Additional troponin levels should be obtained beyond 6 hours after symptom onset in patients with normal troponin levels on serial examination when changes on ECG and/or clinical presentation confer an intermediate or high index of suspicion for ACS, as recommended by the 2014 AHA/ACC guideline for the management of patients with non-ST-elevation acute coronary syndromes 1.
- The specific timing may need adjustment based on the sensitivity of the assay used at your institution, onset of chest pain, and the patient's clinical presentation.
Clinical Application
- For high-sensitivity troponin assays, a 0-1 hour or 0-2 hour protocol may be sufficient, with a second measurement taken 1-2 hours after the initial test.
- In patients with ongoing symptoms or high clinical suspicion but negative initial results, a third measurement at 6 hours is recommended.
- For conventional troponin assays, the 0-3-6 hour protocol remains standard, as supported by the guidelines 1.
From the Research
Interval to Check Troponins
- The optimal interval to check troponins is not explicitly stated in the provided studies, but study 2 suggests that repeat measurements of high-sensitivity cardiac troponin I (hs-cTnI) over hours can identify individuals with acute heart failure without acute coronary syndrome at risk for short- and long-term outcomes.
- In study 2, hs-cTnI was measured ≤12 hours from admission and repeated ≤6 hours thereafter, with a median interval of 3.4±1 hours between measurements.
- The study found that both individual measurements and the change (Δ) in hs-cTnI levels were associated with long-term outcomes, but the second measurement was more strongly associated with short-term outcomes.
- There is no clear consensus on the best interval to check troponins, and the decision may depend on individual patient factors and clinical context.
Clinical Context
- Study 3 discusses the management of acute coronary syndrome, including the use of aspirin, antiplatelet therapy, and beta blockers, but does not provide specific guidance on troponin measurement intervals.
- Study 4 reviews the use of beta blockers, aspirin, and statins in critically ill patients, including those with elevated cardiac troponin levels, but does not address troponin measurement intervals.
- Study 5 examines the effects of beta blockers on outcomes in patients with suspected or diagnosed acute myocardial infarction, but does not provide information on troponin measurement intervals.
- Study 6 investigates the benefit of vasodilating beta blockers in patients with acute myocardial infarction after percutaneous coronary intervention, but does not address troponin measurement intervals.