What is the first test to order for a patient presenting with chest pain?

First Test to Order for a Patient Presenting with Chest Pain

An electrocardiogram (ECG) should be the first test ordered for a patient presenting with chest pain, and it should be acquired and reviewed within 10 minutes of arrival. 1, 2

Initial Diagnostic Approach

• Unless a non-cardiac cause is evident, an ECG should be performed immediately for all patients with chest pain; if unavailable in an office setting, the patient should be referred to the emergency department (ED) 1
• The ECG should be reviewed specifically for ST-segment elevation myocardial infarction (STEMI), ST depression, T-wave inversions, or other arrhythmias that may indicate acute coronary syndrome (ACS) 1, 2
• In patients with nondiagnostic initial ECGs but persistent symptoms or high clinical suspicion, serial ECGs should be performed to detect potential ischemic changes 1
• For patients with intermediate-to-high clinical suspicion for ACS and nondiagnostic initial ECG, supplemental electrocardiographic leads V7 to V9 are reasonable to rule out posterior myocardial infarction 1

Secondary Testing

• After the initial ECG, cardiac troponin (cTn) should be measured as soon as possible in patients with suspected ACS 1, 3
• High-sensitivity cardiac troponin (hs-cTn) is the preferred biomarker as it enables more rapid detection or exclusion of myocardial injury 3
• A chest radiograph should be obtained to evaluate for other potential cardiac, pulmonary, and thoracic causes of chest pain 3, 2

Management Algorithm Based on Initial ECG

• If the ECG shows STEMI: Immediate treatment according to STEMI guidelines 1, 2
• If the ECG shows ST depression or T-wave inversions: Treat according to non-ST-elevation ACS guidelines 1, 2
• If the ECG is nondiagnostic or normal: Proceed with troponin testing and consider serial ECGs if symptoms persist 1

Clinical Significance of ECG Findings

• Patients with chest pain and normal ECGs have extremely low risk for acute myocardial infarction (approximately 1.3%) 4
• Patients with abnormal ECGs showing definite ischemic changes have a high risk of myocardial infarction (>50%) 4
• Patients with abnormal but non-ischemic ECGs (LBBB, RBBB) have an intermediate risk 4

Common Pitfalls to Avoid

• Delaying ECG acquisition beyond 10 minutes of arrival can significantly impact outcomes 1, 2
• Relying on pain response to nitroglycerin as diagnostic of myocardial ischemia is unreliable 2
• In office settings, delaying transfer to the ED for troponin testing when ACS is suspected can worsen outcomes 1, 2
• Dismissing atypical presentations in women, elderly, and diabetic patients who may not present with classic chest pain 5

Special Considerations

• For patients with left bundle branch block or electronically paced ventricular rhythm, adenosine or dipyridamole myocardial perfusion SPECT may be needed for further evaluation 1
• In patients with baseline ECG abnormalities that interfere with interpretation of exercise-induced ST-segment changes, exercise myocardial perfusion SPECT may be useful 1
• For patients with chest pain in whom the initial ECG is consistent with ACS, immediate treatment according to established guidelines is warranted 1

The ECG remains the cornerstone of initial evaluation for chest pain patients due to its wide availability, low cost, and critical diagnostic information that guides immediate management decisions. When combined with troponin testing and chest radiography, it forms the essential triad of initial testing for chest pain evaluation.