What is the initial workup for a patient presenting with chest pain in the emergency department (ED)?

Initial Workup of Chest Pain in the Emergency Department

All patients presenting with chest pain to the ED must have a 12-lead ECG obtained and interpreted within 10 minutes of arrival, and cardiac troponin measured as soon as possible upon presentation. 1, 2

Immediate Actions (Within 10 Minutes)

ECG Acquisition and Interpretation

• Obtain 12-lead ECG within 10 minutes to identify STEMI (ST-segment elevation ≥1 mV in contiguous leads), ST-segment depression, T-wave inversions, or new left bundle branch block 1, 2
• If initial ECG is nondiagnostic but clinical suspicion remains high, repeat ECG every 15-30 minutes during the first hour 2, 3
• Consider supplemental leads V7-V9 to detect posterior MI in patients with intermediate-to-high clinical suspicion 3
• Compare with previous ECGs if available to detect subtle new changes 3

Cardiac Biomarker Testing

• Draw cardiac troponin (preferably high-sensitivity) immediately upon presentation 1, 2
• Obtain serial troponin measurements at 3-6 hours after symptom onset, or at 10-12 hours after the beginning of index chest pain 1, 3
• A rising and/or falling pattern of troponin values is diagnostic for acute myocardial injury 3

Vital Signs and Hemodynamic Stabilization

• Assess and stabilize hemodynamic changes without delay, including pain relief and correction of abnormalities 1
• Check blood pressure in both arms to detect differentials >20 mmHg suggestive of aortic dissection 3
• Assess for orthostatic hypotension (decline >20 mmHg systolic or >10 mmHg diastolic after 1 minute) 3

Focused History Elements

Pain Characteristics (High-Yield Features)

• Quality: Pressure, squeezing, gripping, heaviness, tightness, or constriction suggests ischemia; sharp, stabbing, fleeting, or pleuritic pain suggests lower probability 2
• Onset pattern: Anginal pain builds gradually over minutes; sudden-onset "ripping" or "tearing" pain radiating to the back suggests aortic dissection 1, 2
• Duration: Fleeting pain of few seconds is unlikely ischemic; prolonged ongoing rest pain indicates high risk 1, 2
• Location and radiation: Retrosternal with radiation to left arm, jaw, or neck suggests ACS; pain below umbilicus or localized to very small area is unlikely ischemic 1, 2

Associated Symptoms

• Document presence of: dyspnea, diaphoresis, nausea, vomiting, lightheadedness, presyncope, syncope, or palpitations—all increase ACS likelihood 1, 2
• In women specifically ask about: nausea, fatigue, jaw pain, neck pain, back pain, and epigastric discomfort (more common than classic chest pain) 2, 3
• In elderly (≥75 years) consider ACS when: isolated dyspnea, syncope, acute delirium, or unexplained falls occur without classic chest pain 1, 2

Precipitating and Relieving Factors

• Physical exercise or emotional stress triggering symptoms suggests angina 1
• Occurrence at rest or with minimal exertion suggests ACS 1, 2
• Do NOT use nitroglycerin response as diagnostic criterion—esophageal spasm and other conditions respond similarly 1, 2, 3

Cardiovascular Risk Factors

• Age, sex, diabetes mellitus, hypertension, hyperlipidemia, smoking, and family history of premature coronary artery disease 2

Focused Physical Examination

Cardiovascular Examination

• Perform focused cardiovascular exam to identify complications or alternative diagnoses 1
• Look for: diaphoresis, tachypnea, tachycardia, hypotension, jugular venous distension, crackles, S3 gallop, new murmurs (especially aortic regurgitation), or pericardial friction rub 2, 3
• Check for pulse differentials between extremities (suggests aortic dissection) 3
• Assess for unilateral absence of breath sounds with hyperresonant percussion (suggests pneumothorax) 3, 4

Risk Stratification and Disposition

High-Risk Features Requiring CCU Admission

• Severe continuing pain, ischemic ECG changes, positive troponin test (>99th percentile), left ventricular failure, hemodynamic instability 1
• If STEMI identified: Door-to-balloon time <90 minutes (primary PCI preferred) or door-to-needle time <30 minutes (thrombolysis) 1, 2
• If acute coronary syndrome suspected: Give aspirin 160-325 mg immediately (chewed, not swallowed) unless contraindicated 1, 2

Intermediate-Risk Features

• Prior history of MI or CAD, age >70 years, diabetes mellitus, rest angina >20 minutes that has resolved 2
• Apply validated risk scores (TIMI or GRACE) to guide management intensity 2, 3

Low-Risk Features

• Normal ECG, negative troponin at presentation and 6-12 hours, no high-risk features 1
• These patients can be evaluated in chest pain unit for 10-12 hours observation or proceed to stress testing before discharge 1

Life-Threatening Differential Diagnoses to Exclude

When ECG and Troponin Are Normal But Severe Pain Persists

• Pulmonary embolism: Acute dyspnea with pleuritic chest pain, tachycardia (>90% of cases), tachypnea, risk factors (immobility, recent surgery, malignancy) 1, 3, 4
• Aortic dissection: Sudden "ripping" pain to back, pulse differential, blood pressure differential >20 mmHg, new aortic regurgitation murmur—contraindication to antithrombotic therapy 1, 3
• Acute pericarditis: Sharp pleuritic pain improving when sitting forward, worsening supine, widespread ST-elevation with PR depression on ECG, friction rub 1, 4
• Pneumothorax: Severe dyspnea, unilateral absence of breath sounds, tracheal deviation, hyperresonant percussion 1, 3, 4

Critical Pitfalls to Avoid

• Do NOT delay transfer to ED for office-based troponin testing when ACS is suspected—transport urgently by EMS 1, 2, 3, 4
• Do NOT assume young age excludes ACS—it can occur in adolescents without risk factors 2
• Do NOT rely on single normal ECG—up to 6% of patients with evolving ACS are discharged with normal ECG; left circumflex or right coronary occlusions may be "electrically silent" 3
• Do NOT assume reproducible chest wall tenderness excludes serious pathology—7% of patients with palpable tenderness have ACS 2, 4
• Do NOT base decisions on nitroglycerin response—it is not diagnostic for myocardial ischemia 1, 2, 3, 4
• Do NOT initiate antithrombotic therapy until aortic dissection is excluded—it is an absolute contraindication 3

Additional Diagnostic Testing

Chest Radiography

• Obtain to evaluate for pneumothorax, pneumonia, pleural effusion, widened mediastinum (aortic dissection), or pulmonary congestion 3, 4
• Do not delay urgent interventions if indicated while waiting for chest X-ray 3
• Normal chest X-ray does not exclude PE or ACS 3

Advanced Imaging When Indicated

• CT angiography for suspected aortic dissection or pulmonary embolism in stable patients 3
• Transthoracic echocardiography for suspected pericardial tamponade, pericardial effusion, or wall motion abnormalities 2, 3