Essential Laboratory Tests for Chest Pain Evaluation
For patients presenting with chest pain, cardiac troponin (cTn) measurement should be the primary laboratory test, with high-sensitivity troponin (hs-cTn) preferred when available, accompanied by an ECG and chest radiograph to evaluate for cardiac and non-cardiac causes. 1
Initial Laboratory Evaluation
- Serial cardiac troponin (cTn) I or T levels should be obtained to identify abnormal values and rising/falling patterns indicative of acute myocardial injury 1
- High-sensitivity cardiac troponin (hs-cTn) is the preferred biomarker as it enables more rapid detection or exclusion of myocardial injury and increases diagnostic accuracy 1
- For patients with suspected ACS, initial troponin should be measured as soon as possible after presentation to the emergency department 1
- Serial troponin measurements should follow specific timing protocols: 1-3 hours after initial sample for high-sensitivity assays and 3-6 hours for conventional troponin assays 1
Timing Considerations
- For patients with symptoms that began at least 3 hours before ED arrival, a single hs-cTn concentration below the limit of detection on initial measurement may reasonably exclude myocardial injury 1
- Serial troponin measurements are particularly important when clinical suspicion of ACS is high, symptoms persist, or clinical condition deteriorates 1
- With high-sensitivity troponin assays, the "rule-out" protocol can be accelerated compared to conventional assays 1
Additional Testing
- Chest radiograph should be obtained to evaluate for other potential cardiac, pulmonary, and thoracic causes of chest pain 1
- With the availability of cardiac troponin, other cardiac biomarkers such as creatine kinase myocardial (CK-MB) isoenzyme and myoglobin are not useful for diagnosis of acute myocardial injury 1
- For patients with suspected pulmonary embolism, D-dimer testing may be appropriate based on pretest probability assessment 2
- In patients with suspected heart failure, brain natriuretic peptide (BNP) measurement can help clarify the diagnosis, particularly in the presence of dyspnea 2
Special Considerations
- Clinicians should be familiar with the analytical performance and the 99th percentile upper reference limit that defines myocardial injury for the specific troponin assay used at their institution 1
- For patients with chest pain and suspected ACS initially evaluated in the office setting, delayed transfer to the ED for troponin or other diagnostic testing should be avoided 1
- Previous testing results, when available, should be considered and incorporated into clinical decision pathways 1
- Institutions should implement a standardized clinical decision pathway that includes a protocol for troponin sampling based on their particular assay 1
Laboratory Testing Based on Risk Stratification
- For low-risk patients (30-day risk of death or MACE <1%), discharge without admission or urgent cardiac testing may be reasonable after appropriate troponin evaluation 1
- For intermediate-risk patients, additional cardiac testing beyond initial laboratory evaluation may be needed 1
- For high-risk patients (including those with new ischemic ECG changes, troponin-confirmed acute myocardial injury, or hemodynamic instability), more aggressive evaluation and management is recommended 1
Remember that laboratory testing is just one component of chest pain evaluation and should be interpreted in conjunction with clinical presentation, ECG findings, and imaging studies to guide appropriate management.