What are the initial diagnostic tests for a patient presenting with chest pain?

Initial Diagnostic Tests for Chest Pain

Obtain a 12-lead ECG within 10 minutes of patient arrival and measure cardiac troponin (preferably high-sensitivity) as soon as possible—these two tests form the foundation of acute chest pain evaluation. 1

Immediate Testing (Within 10 Minutes)

Electrocardiogram (ECG)

• Acquire and interpret a 12-lead ECG within 10 minutes of arrival in any setting where acute coronary syndrome (ACS) is suspected 1
• If ST-segment elevation, new ST depression, or new left bundle branch block is present, immediately activate STEMI or NSTE-ACS protocols 1
• Perform serial ECGs if the initial tracing is nondiagnostic, especially when clinical suspicion remains high, symptoms persist, or the patient's condition deteriorates 1
• Consider supplemental leads V7-V9 in patients with intermediate-to-high ACS suspicion and a nondiagnostic initial ECG to detect posterior myocardial infarction 1

Critical pitfall: Up to 6% of patients with evolving ACS are discharged with a normal ECG—never base decision-making solely on a single normal or nondiagnostic ECG 1

Laboratory Testing

Cardiac Troponin

• Measure cardiac troponin (cTn I or T) as soon as possible after presentation in all patients with suspected ACS 1
• High-sensitivity troponin is the preferred biomarker because it enables more rapid detection or exclusion of myocardial injury and increases diagnostic accuracy 1
• Repeat troponin measurements at the following intervals after initial collection (time zero): 1
  • 1-3 hours for high-sensitivity troponin assays
  • 3-6 hours for conventional troponin assays
• For patients with acute chest pain, normal ECG, and symptoms beginning at least 3 hours before ED arrival, a single high-sensitivity troponin below the limit of detection at time zero is reasonable to exclude myocardial injury 1

Obsolete Biomarkers

• Do not use creatine kinase MB (CK-MB) or myoglobin for diagnosis of acute myocardial injury when troponin is available 1

Imaging Studies

Chest Radiography

• Obtain a chest X-ray to evaluate for alternative cardiac, pulmonary, and thoracic causes of symptoms including pneumonia, pneumothorax, widened mediastinum, heart failure, and pleural effusion 1, 2

Echocardiography

• For intermediate-risk patients with acute chest pain, transthoracic echocardiography (TTE) is recommended as a rapid bedside test to establish baseline ventricular and valvular function, evaluate for wall motion abnormalities, and assess for pericardial effusion 1

Risk Stratification After Initial Testing

Implement a clinical decision pathway (CDP) that categorizes patients into low-, intermediate-, and high-risk strata to facilitate disposition and subsequent diagnostic evaluation 1

High-Risk Features Requiring Urgent Action

• Recurrent ischemia, elevated troponin levels, hemodynamic instability, major arrhythmias, or early post-infarction unstable angina require urgent coronary angiography 2

Low-Risk Patients

• Patients with acute chest pain and <1% 30-day risk of death or major adverse cardiovascular events (MACE) should be designated as low risk 1
• Discharge home without admission or urgent cardiac testing is reasonable for low-risk patients 1

Intermediate-Risk Patients

• Management in an observation unit is reasonable to shorten length of stay and lower cost relative to inpatient admission 1

Setting-Specific Considerations

Office Setting

• If an ECG cannot be obtained in the office, immediately refer the patient to the ED 1
• Transport patients with clinical evidence of ACS or life-threatening chest pain urgently to the ED by EMS, not by private vehicle 1, 2
• Never delay transfer for troponin or other diagnostic testing beyond the ECG in the office setting 1, 2

EMS transport advantages: Acquisition of prehospital ECG (facilitating reperfusion if ST elevation present), presence of trained personnel who can treat chest pain and arrhythmias en route, and shorter travel time to the ED 1

Common Pitfalls to Avoid

• Do not rely on clinical features alone to diagnose ACS in patients with normal or nondiagnostic ECG—clinical features have very limited diagnostic value 3
• Compare the current ECG with previous ECGs when available, as left ventricular hypertrophy, bundle branch blocks, and ventricular pacing may mask signs of ischemia 1
• Institutions should implement a standardized CDP with a protocol for troponin sampling based on their particular assay 1
• Consider previous cardiac testing when available and incorporate it into clinical decision pathways 1