What is the initial management for a patient presenting with Acute Coronary Syndrome (ACS) in the emergency room?

Clinical Pathway for Acute Coronary Syndrome in the Emergency Department

Immediate Actions (Within 10 Minutes of Arrival)

All patients with suspected ACS must be seen immediately by a qualified physician, with a 12-lead ECG obtained within 10 minutes of first medical contact to guide the treatment pathway. 1, 2

Initial Assessment Triad

• Symptom evaluation: Document chest pain quality, duration, radiation, and associated symptoms (dyspnea, diaphoresis, nausea, lightheadedness) 1
• Physical examination: Assess hemodynamic stability, signs of heart failure (S3 gallop, pulmonary rales, new mitral regurgitation), and peripheral perfusion 1
• 12-lead ECG: Identify ST-segment elevation, ST-segment depression >0.5mm, T-wave inversions, or transient ST-elevation 1

Critical Pitfall: Atypical Presentations

Women and elderly patients frequently present without chest pain—instead with dyspnea, fatigue, nausea, or epigastric discomfort—and have twice the mortality risk when these symptoms are missed 2

ECG-Based Triage (Determines Pathway)

STEMI Pathway (Persistent ST-Elevation ≥1mm in ≥2 Contiguous Leads)

• Activate catheterization lab immediately for primary PCI within 120 minutes 1, 3
• If PCI unavailable within 120 minutes: administer fibrinolytic therapy (alteplase, reteplase, or tenecteplase at full dose if age <75 years; half dose if ≥75 years) 3
• Transfer to PCI-capable facility within 24 hours after fibrinolysis 3

NSTE-ACS Pathway (ST-Depression, T-Wave Inversion, or Normal ECG)

Proceed to Step 2 below for biomarker-based risk stratification 1

Step 2: Immediate Medical Therapy (While Awaiting Biomarkers)

Initiate the following treatments immediately when ACS diagnosis appears likely:

Antiplatelet Therapy

• Aspirin: 150-300 mg non-enteric loading dose, then 75-100 mg daily (IV acceptable) 1
• P2Y12 inhibitor: Loading dose of ticagrelor or clopidogrel 1
  • Critical timing note: For NSTE-ACS, do NOT give prasugrel until coronary anatomy is known at catheterization 4
  • Prasugrel contraindicated if prior TIA/stroke, age ≥75 years (except high-risk diabetes/prior MI), weight <60kg, or likely urgent CABG 4

Anticoagulation (Choose ONE)

• Fondaparinux: 2.5 mg subcutaneous daily (preferred for conservative strategy) 1
• Enoxaparin: 1 mg/kg subcutaneous twice daily 1
• UFH: IV bolus 60-70 IU/kg (max 5000 IU), then infusion 12-15 IU/kg/h (max 1000 IU/h) titrated to aPTT 1.5-2.5× control 1
• Bivalirudin: Only if invasive strategy planned 1

Adjunctive Therapy

• Oral β-blocker: If tachycardic or hypertensive WITHOUT signs of heart failure, bradycardia <60 bpm, hypotension <100 mmHg, or heart block 1
  • No benefit to routine IV β-blockers; give orally within 24 hours 1
• Nitrates: Oral or IV for persistent/recurrent chest pain 1
• Oxygen: Only if SpO2 <94%, dyspnea, heart failure, or shock 1
• Morphine: For pain relief unresponsive to nitrates 5

Step 3: Biomarker Assessment and Risk Stratification (Within 60 Minutes)

Draw blood on arrival; results must be available within 60 minutes 1

Required Tests

• High-sensitivity troponin (preferred) or cardiac troponin T/I 1, 3
• Hemoglobin (detect anemia) 1
• Creatinine/eGFR (dose adjustments, contrast risk) 1
• Glucose (screen for diabetes) 1

Troponin Interpretation Algorithm

• If troponin elevated on arrival: Proceed to high-risk pathway 1
• If troponin normal and symptoms >6 hours: Discharge if pain-free and GRACE score <140 1
• If troponin normal and symptoms <6 hours: Repeat troponin at 3 hours 1
  • Any rise (delta change) = NSTEMI → high-risk pathway 1
  • No change = consider stress testing or discharge with outpatient follow-up 1

Step 4: Invasive Strategy Timing (NSTE-ACS)

Immediate Angiography (<2 Hours)

Emergency coronary angiography is mandatory for: 1

• Cardiogenic shock or hemodynamic instability
• Severe ongoing ischemia despite medical therapy
• Life-threatening arrhythmias (sustained VT, VF)
• Mechanical complications (acute MR, VSD)

Early Invasive Strategy (Within 24 Hours)

Coronary angiography within 24 hours is recommended for patients with ANY of the following high-risk criteria: 1

• Elevated troponin (NSTEMI diagnosis)
• Dynamic or new contiguous ST/T-segment changes suggesting ongoing ischemia
• Transient ST-segment elevation
• GRACE risk score >140
• Recurrent angina/ischemia at rest or with low-level activity despite medical therapy
• Recurrent ischemia with heart failure signs
• Diabetes mellitus
• Depressed LV function (EF <40%)
• PCI within past 6 months
• Prior CABG

Selective Invasive Strategy (After Stress Testing)

For low-risk patients (GRACE <140, no high-risk features, pain-free, negative serial troponins): 1

• Perform stress testing or coronary CT angiography before discharge
• If positive, proceed to angiography
• If negative, discharge with cardiology follow-up within 72 hours

Step 5: Observation Period (6-12 Hours for Non-High-Risk Patients)

Continuous Monitoring

• Multi-lead ECG ischemia monitoring 1
• Obtain 12-lead ECG with any recurrent chest pain and compare to pain-free tracing 1
• Monitor for hemodynamic instability (hypotension, pulmonary edema) 1
• Repeat troponin at 6-12 hours if initial negative 1

Echocardiography Indications

• Assess LV function 1
• Exclude mechanical complications (acute MR, VSD, free wall rupture) 1
• Evaluate for alternative diagnoses (pericarditis, aortic dissection) 1, 2

Critical Differential Diagnoses to Exclude

Life-threatening cardiovascular causes requiring different management: 1, 2

• Aortic dissection: Widened mediastinum on CXR, pulse differential, severe tearing pain radiating to back
• Pulmonary embolism: Hypoxia, tachycardia, right heart strain on ECG
• Tension pneumothorax: Absent breath sounds, tracheal deviation, hypotension
• Pericardial tamponade: Muffled heart sounds, pulsus paradoxus, electrical alternans

Special Populations

Chronic Kidney Disease

• Apply same diagnostic and therapeutic strategies with dose adjustments 1
• Use low- or iso-osmolar contrast at lowest possible volume 1
• Assess eGFR in all patients before contrast administration 1

Elderly Patients (≥75 Years)

• Apply same interventional strategies as younger patients 1
• Prasugrel generally not recommended due to increased bleeding risk unless high-risk features (diabetes, prior MI) 4
• Adjust antithrombotic dosing for renal function 1

Patients <60 kg Body Weight

• Consider prasugrel maintenance dose reduction to 5 mg daily (if used) due to increased bleeding risk 4
• Standard aspirin and other antiplatelet dosing 4

Key Pitfalls to Avoid

• Do not delay reperfusion for consultations—mortality increases with every minute of delay 2, 3
• Do not give prasugrel before knowing coronary anatomy in NSTE-ACS—wait until catheterization 4
• Do not routinely give IV β-blockers—no mortality benefit and increased shock risk; use oral within 24 hours 1
• Do not give oxygen routinely—only if hypoxemic, dyspneic, or in heart failure 1
• Do not discharge patients with ongoing symptoms even if initial troponin negative—repeat at 3-6 hours 1
• Do not miss atypical presentations in women and elderly—dyspnea alone carries twice the mortality 2
• Do not use fondaparinux alone during PCI—increased catheter thrombosis risk; add UFH 1