What is the immediate management for a male patient presenting with left-sided chest pain and a normal electrocardiogram (ECG)?

Immediate Management of Male Patient with Left-Sided Chest Pain and Normal ECG

A normal ECG does not exclude acute coronary syndrome (ACS)—immediately measure high-sensitivity cardiac troponin, perform serial ECGs, and continue observation with cardiac monitoring until ACS is definitively ruled out. 1

Critical First Steps (Do Not Delay)

• Measure cardiac troponin immediately (preferably high-sensitivity troponin T or I) as it is the most sensitive test for diagnosing acute myocardial injury, and a normal ECG alone is insufficient to exclude ACS 1, 2
• Perform serial ECGs every 15-30 minutes during the first hour if symptoms persist or recur, as up to 6% of patients with evolving ACS present with an initially normal ECG 1, 3
• Obtain chest radiograph to evaluate alternative cardiac, pulmonary, and thoracic causes including pneumonia, pneumothorax, aortic dissection (widened mediastinum), or heart failure 1, 4

Serial Monitoring Protocol

• Repeat troponin measurement at 6-12 hours from symptom onset to detect rising or falling patterns that indicate myocardial injury 2, 5
• Continue serial ECGs immediately if chest pain recurs, persists, or clinical condition deteriorates, as ongoing symptoms increase likelihood of capturing evolving ischemic changes 1, 5
• Consider supplemental leads V7-V9 if intermediate-to-high clinical suspicion for ACS persists, as left circumflex or right coronary artery occlusions causing posterior wall ischemia are often "electrically silent" on standard 12-lead ECG 1

Risk Stratification After Initial Testing

High-Risk Features Requiring Admission and Urgent Intervention:

• Recurrent or persistent ischemic chest pain despite medical therapy 5, 4
• Dynamic ECG changes on serial tracings 5
• Positive second troponin measurement or rising pattern 2, 5
• Hemodynamic instability, life-threatening arrhythmias, or new/worsening heart failure 5

Low-Risk Criteria Allowing Potential Discharge:

• No recurrent chest pain after 6-12 hours of observation 5
• Normal or unchanged ECG on serial testing 5
• Two negative troponin measurements 5
• No high-risk features present 5

Disposition Algorithm

For high-risk patients: Admit to hospital with continuous cardiac monitoring and consider urgent coronary angiography (ideally within hours, not days) 2, 5

For intermediate-risk patients: Continue observation in chest pain unit or ED with serial ECGs and troponins until the 6-12 hour mark; consider anatomic or functional testing before discharge 5

For low-risk patients: Consider early stress test to provoke ischemia before discharge, with outpatient follow-up within 72 hours 5

Critical Pitfalls to Avoid

• Never rely on a single normal ECG to exclude ACS—this is a dangerous practice that accounts for missed myocardial infarctions in 1-4% of patients with normal initial ECGs 3, 1
• Do not delay transfer to ED for troponin testing if patient is in office setting—delayed transfer for diagnostic testing beyond the ECG can be detrimental 1, 2
• Do not use nitroglycerin response as diagnostic of myocardial ischemia, as it is not reliable 4
• History remains the most important tool—overreliance on a normal ECG in a patient with classic anginal chest pain is dangerous 3

Additional Diagnostic Considerations

• Assess for non-cardiac causes: The normal ECG may represent pericarditis (look for diffuse ST elevation), pulmonary embolism, aortic dissection, pneumothorax, or musculoskeletal pain 1, 6
• Obtain basic laboratory tests: Complete blood count (to detect anemia as contributor), lipid profile, creatinine with renal function estimation, and glycemic status 1, 2
• Consider echocardiography if diagnosis remains unclear, as regional wall motion abnormalities occur within seconds of coronary occlusion, though absence of wall motion abnormalities effectively excludes major myocardial infarction 1