What is the recommended emergency department protocol for evaluating and managing a patient presenting with chest pain?

Emergency Department Chest Pain Protocol

All patients presenting with acute chest pain should have an ECG obtained and reviewed within 10 minutes of arrival to identify STEMI, and cardiac troponin should be measured as soon as possible after presentation. 1, 2

Immediate Assessment (Within 5-10 Minutes)

• Place patient on continuous cardiac monitoring with emergency resuscitation equipment and defibrillator at bedside 3
• Obtain 12-lead ECG within 10 minutes to identify ST-segment elevation myocardial infarction or other life-threatening conditions 1, 3
• Establish IV access and check vital signs including oxygen saturation 3
• Administer aspirin 160-325 mg (chewed) unless contraindicated by active bleeding or known allergy 3
• Provide pain relief and stabilize hemodynamics without delay 1

Initial Diagnostic Workup

Laboratory Testing

• Draw cardiac troponin immediately upon presentation, with repeat measurement at 3-6 hours after symptom onset 1, 2
• Obtain CK-MB mass on admission and at 10-12 hours after symptom onset 1
• High-sensitivity troponin has >95% negative predictive value for myocardial infarction when negative on admission 2

Serial ECG Monitoring

• Perform serial ECGs every 15-30 minutes during the first hour if initial ECG is normal but clinical suspicion remains intermediate to high 2
• Consider supplemental leads V7-V9 to exclude posterior myocardial infarction, which can be electrically silent on standard leads 3, 2
• Compare with previous ECGs if available to detect subtle changes 2
• A normal initial ECG does not exclude acute coronary syndrome—up to 6% of patients with evolving ACS are discharged with normal ECGs 2

Risk Stratification and Triage

High-Risk Features Requiring Immediate CCU Admission

• Severe continuing pain with ischemic ECG changes 1
• Positive troponin test 1
• Left ventricular failure or hemodynamic abnormalities 1
• Prolonged chest pain at rest with associated dyspnea, tachycardia, or hypotension 2
• New murmur of aortic regurgitation 2
• Age ≥75 years with accompanying symptoms such as shortness of breath, syncope, acute delirium, or unexplained fall 1, 2

Medical Management for Suspected ACS

• Administer sublingual nitroglycerin 0.3 mg every 5 minutes for up to 3 doses if systolic BP >90 mmHg 3
• Consider IV nitroglycerin for persistent ischemia, heart failure, or hypertension 3
• Give morphine IV as preferred analgesic, titrated to pain severity 3
• Start low-molecular-weight heparin in the emergency department for suspected acute coronary syndrome 1
• If ST-segment elevation indicates evolving Q-wave infarction, initiate thrombolytic treatment within 30 minutes 1

Life-Threatening Differential Diagnoses to Exclude

Critical Conditions Beyond ACS

• Aortic dissection: Look for sudden onset ripping chest pain radiating to back, pulse differential, blood pressure differential, or widened mediastinum on chest radiograph 1, 2, 4
• Pulmonary embolism: Consider even when chest radiograph, ECG, and arterial blood gases are normal; use validated clinical decision rules 4
• Pneumothorax: Evaluate for dyspnea, pain on inspiration, and unilateral absence of breath sounds 4
• Cardiac tamponade: Assess for dyspnea, chest discomfort, hypotension; use transthoracic echocardiography for immediate diagnosis 2
• Esophageal rupture: Consider in appropriate clinical context 1

Physical Examination Red Flags

• Diaphoresis, tachypnea, tachycardia, or hypotension 2
• New cardiac murmur 2
• Pericardial friction rub (suggests pericarditis) 2, 4
• Differential pulses or blood pressures (suggests aortic dissection) 2

Observation and Disposition Strategy

Chest Pain Unit Observation (10-12 Hours)

• Most patients without high-risk features should be evaluated in chest pain units rather than discharged directly from the emergency department 1
• The risk of missed acute coronary syndrome without proper observation is substantial—historically 20-30% died or had MI within 4 weeks in unstable angina 1
• Chest pain units should have resuscitation equipment, cardiac rhythm monitoring, blood pressure monitoring, and continuous ST-segment monitoring 1

Disposition Decisions

• Admit to CCU: Confirmed or suspected ACS with high-risk features 1, 3
• Observe in chest pain unit or admit to hospital: Intermediate risk with abnormal initial evaluation 2
• Outpatient management: Low risk with normal ECG and troponin 2

Special Population Considerations

Women and Elderly Patients

• Women may present with atypical symptoms—maintain high suspicion for ACS and emphasize accompanying symptoms more common in women 3, 4
• Patients ≥75 years should be considered for ACS when presenting with shortness of breath, syncope, acute delirium, or unexplained falls, even without classic chest pain 1, 4

Critical Pitfalls to Avoid

• Never delay transfer from office setting to ED for troponin or diagnostic testing in suspected ACS 1
• Do not rely on clinical grounds alone to exclude acute coronary syndrome 5
• Do not discharge patients with normal initial ECG without serial monitoring and troponin testing 2
• Exclude aortic dissection before initiating antithrombotic therapy for suspected ACS, as this is a critical contraindication 2