From the Guidelines
Troponin levels should be ordered in the emergency department for patients presenting with symptoms suggestive of acute coronary syndrome (ACS), with the initial troponin drawn at presentation and a second test typically performed 3-6 hours later to detect a rise or fall in levels, as recommended by the 2017 AHA/ACC guideline 1.
Key Points to Consider
- The 2017 AHA/ACC guideline recommends measuring cardiac-specific troponin (troponin I or T) at presentation and 3 to 6 hours after symptom onset in all patients with suspected ACS to identify a rising and/or falling pattern of values 1.
- 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 1.
- High-sensitivity troponin assays may allow for a second test to be performed as early as 1-2 hours after the first, as noted in the 2015 American Heart Association guidelines update for cardiopulmonary resuscitation and emergency cardiovascular care 1.
Clinical Scenarios Warranting Troponin Testing
- Unexplained hypotension
- Arrhythmias
- Syncope in patients with cardiovascular risk factors
- Post-cardiac arrest
Importance of Clinical Correlation
- Troponin elevation may occur in conditions other than ACS, such as pulmonary embolism, heart failure, myocarditis, and renal failure, so clinical correlation is essential for proper interpretation 1.
- The test helps differentiate between cardiac and non-cardiac causes of symptoms and guides treatment decisions regarding antiplatelet therapy, anticoagulation, and potential cardiac catheterization 1.
From the Research
Troponin Levels in Emergency Room Setting
When to order troponin levels in an Emergency Room (ER) setting is crucial for diagnosing acute coronary syndrome (ACS). The following points highlight the key considerations:
- Patients with symptoms suggestive of ACS should have troponin levels checked, especially if they have a negative electrocardiogram (EKG) 2.
- High-sensitivity troponin measurements are the preferred test to evaluate for non-ST-segment elevation myocardial infarction (NSTEMI) 3.
- Troponin levels should be measured at 0 hours and 2 hours after presentation to improve diagnostic and prognostic test performance 4.
- Stratified reporting of high-sensitivity troponin I assay can lead to suboptimal management of patients with ACS and intermediate troponin elevation 5.
- Combining Heart Fatty Acid Binding Protein (H-FABP) with cardiac troponin can help develop an optimal rule-out strategy for acute myocardial infarction (AMI) 6.
Key Considerations for Troponin Ordering
Some key points to consider when ordering troponin levels in an ER setting include:
- Timing of troponin measurement: measuring troponin levels at 6-9 hours after symptom onset can help identify low-risk patients who can be discharged from the ER 2.
- Type of troponin assay: high-sensitivity troponin assays are preferred for evaluating NSTEMI 3.
- Combination with other biomarkers: combining troponin with other biomarkers like H-FABP can improve diagnostic accuracy 6.
- Stratified reporting: stratified reporting of troponin levels can lead to suboptimal management of patients with intermediate troponin elevation 5.
Clinical Implications
The clinical implications of troponin ordering in an ER setting include:
- Rapid identification of low-risk patients who can be discharged from the ER, reducing unnecessary hospital admissions 2, 6.
- Improved diagnostic accuracy for NSTEMI using high-sensitivity troponin assays 3.
- Potential for suboptimal management of patients with intermediate troponin elevation due to stratified reporting 5.
- Need for careful consideration of troponin ordering and interpretation in the ER setting to ensure optimal patient care 2, 3, 4, 5, 6.