What is the management approach for patients with acute coronary syndromes, including ST-Elevation Myocardial Infarction (STEMI) and Non-ST-Elevation Myocardial Infarction (NSTEMI)?

Management of Acute Coronary Syndromes: STEMI and NSTEMI

Primary percutaneous coronary intervention (PCI) is the preferred reperfusion strategy for STEMI patients, while NSTEMI patients require risk stratification to determine the timing of invasive management. 1

Initial Assessment and Diagnosis

• A 12-lead ECG should be acquired and interpreted within 10 minutes of first medical contact to identify patients with STEMI 1
• Based on ECG findings, patients with suspected ACS can be classified into:
  • STEMI: ST-segment elevation in ≥2 contiguous leads on standard 12-lead ECG 1
  • NSTE-ACS: ST-segment depression, T-wave inversion, or normal ECG 1
• High-sensitivity cardiac troponin measurements are essential for diagnosis of myocardial infarction 1
• Vital signs assessment and cardiac monitoring should be initiated promptly 1

Management of STEMI

Immediate Management

• Emergency reperfusion therapy is the cornerstone of STEMI treatment 1
• Primary PCI is the preferred reperfusion strategy when it can be performed in a timely manner (within 120 minutes of first medical contact) 2
• If PCI cannot be performed within 120 minutes, fibrinolytic therapy should be administered, followed by transfer to a PCI-capable facility 3, 2

Pharmacological Therapy

• Antithrombotic therapy:
  • Aspirin (loading dose 150-300 mg, then 75-100 mg daily) 1
  • P2Y12 inhibitor:
    • Prasugrel (60 mg loading dose, 10 mg daily) in patients undergoing PCI without history of stroke/TIA 4
    • Clopidogrel (300 mg loading dose, 75 mg daily) for patients not eligible for prasugrel 5
  • Anticoagulation with unfractionated heparin or low-molecular-weight heparin 1
• Adjunctive therapy:
  • Beta-blockers for patients without contraindications 6
  • ACE inhibitors for patients with anterior infarction, heart failure, or reduced ejection fraction 1
  • Statins should be initiated early 1

Surgical Management

• Emergency CABG is indicated in STEMI patients with:
  • Failed PCI with persistent pain or hemodynamic instability 1
  • Persistent or recurrent ischemia refractory to medical therapy 1
  • Cardiogenic shock with multivessel or left main disease 1
  • Life-threatening ventricular arrhythmias with significant left main or triple-vessel disease 1

Management of NSTEMI

Risk Stratification

• Patients with NSTE-ACS should be risk stratified to determine the timing of invasive management 1
• Very high-risk features requiring immediate invasive strategy (<2 hours):
  • Hemodynamic instability or cardiogenic shock
  • Recurrent or ongoing chest pain refractory to medical treatment
  • Life-threatening arrhythmias
  • Mechanical complications of MI
  • Acute heart failure with refractory angina or ST deviation 1

Timing of Invasive Strategy

• Immediate invasive strategy (<2 hours): For patients with very high-risk features 1
• Early invasive strategy (<24 hours): For patients with high-risk features (e.g., dynamic ST/T changes, elevated troponin) 1
• Invasive strategy (<72 hours): For patients with intermediate-risk features 1
• Selective invasive strategy: For low-risk patients, consider non-invasive stress testing first 1

Pharmacological Therapy

• Antithrombotic therapy:
  • Aspirin (loading dose 150-300 mg, then 75-100 mg daily) 1
  • P2Y12 inhibitor:
    • Ticagrelor (preferred over clopidogrel) for conservative strategy 1
    • Prasugrel only after coronary angiography when PCI is planned 1, 4
    • Clopidogrel when other agents are contraindicated 5
  • Parenteral anticoagulation (unfractionated heparin, enoxaparin, fondaparinux) 1
• Adjunctive therapy:
  • Beta-blockers for patients without contraindications 6
  • ACE inhibitors for patients with heart failure, hypertension, or diabetes 1
  • Statins should be initiated early 1

Special Considerations

• Cardiogenic shock: Patients with cardiogenic shock should be transferred immediately to a PCI-capable facility 1
• Elderly patients (≥75 years): Consider dose adjustments of antithrombotic medications due to increased bleeding risk 4
• Low body weight (<60 kg): Consider lower maintenance doses of prasugrel (5 mg daily) 4
• Diabetes mellitus: More aggressive antithrombotic therapy may be warranted 4

Common Pitfalls and Caveats

• Delayed diagnosis: Failure to obtain and interpret ECG within 10 minutes of first medical contact can lead to delayed reperfusion 1
• Inappropriate risk stratification: Underestimating risk in NSTEMI patients may lead to delayed invasive management 1, 7
• Bleeding complications: Careful assessment of bleeding risk is essential when selecting antithrombotic therapy 4, 5
• Prasugrel is contraindicated in patients with prior stroke/TIA and generally not recommended in patients ≥75 years 4
• Discontinuation of dual antiplatelet therapy increases risk of stent thrombosis and recurrent events 4
• Patients with NSTEMI and ongoing ischemia should undergo immediate angiography regardless of biomarker status 1, 7