What is the management of Non-ST-Elevation Myocardial Infarction (NSTEMI)?

Management of Non-ST-Elevation Myocardial Infarction (NSTEMI)

Early invasive strategy with coronary angiography within 24-48 hours is recommended for high-risk NSTEMI patients, along with dual antiplatelet therapy, anticoagulation, and other cardioprotective medications. 1

Initial Assessment and Risk Stratification

• Diagnosis of NSTEMI is confirmed by:

  • Characteristic chest pain/discomfort (may radiate to left arm, neck, jaw, or back)
  • ECG changes (ST-segment depression ≥0.5 mm, T-wave inversions >1 mm)
  • Elevated cardiac troponins (serial measurements at presentation and 3-6 hours later)
  • Note: ~43.6% of NSTEMI patients may present without chest pain, particularly elderly, women, and those with diabetes 1

• Risk stratification using validated scoring systems:

  • TIMI Risk Score
  • GRACE Risk Score
  • PURSUIT Risk Score
  • High-risk features: age ≥65 years, ≥3 coronary risk factors, ST-segment deviation, ≥2 anginal episodes in 24 hours, elevated cardiac markers, prior aspirin use 1

Immediate Pharmacological Management

Antiplatelet Therapy

1. Aspirin:

   • Loading dose: 150-300 mg
   • Maintenance: 75-100 mg daily (long-term) 1

2. P2Y12 inhibitor (choose one):

   • Clopidogrel: 300-600 mg loading dose, then 75 mg daily 2
   • Ticagrelor: 180 mg loading dose, then 90 mg twice daily
   • Prasugrel: 60 mg loading dose, then 10 mg daily (only after coronary anatomy is established) 3
   • Note: Prasugrel is contraindicated in patients with prior stroke/TIA and generally not recommended in patients ≥75 years 3

Anticoagulation (choose one)

• Unfractionated heparin: 60-70 U/kg IV bolus, then 12-15 U/kg/hr
• Enoxaparin: 1 mg/kg SC every 12 hours
• Fondaparinux: Preferred in patients with increased bleeding risk 4, 1

Anti-ischemic Therapy

• Beta-blockers: First-line therapy unless contraindicated
• Nitroglycerin: For ongoing chest pain
• Calcium channel blockers: Alternative for patients with contraindications to beta-blockers

Invasive vs. Conservative Strategy

Early Invasive Strategy (within 24-48 hours)

• Indicated for high-risk patients:
  • Refractory angina
  • Hemodynamic or electrical instability
  • Elevated cardiac biomarkers
  • Dynamic ST-segment changes
  • GRACE score >140 4, 1

Conservative (Selective Invasive) Strategy

• May be considered for:
  • Low-risk patients
  • Patients with extensive comorbidities where risks outweigh benefits
  • Patients who will not consent to revascularization 4
• Stress testing should be performed to identify patients who may benefit from invasive management 4

Revascularization Considerations

• Percutaneous Coronary Intervention (PCI):

  • Continue aspirin
  • Administer loading dose of P2Y12 inhibitor if not given previously
  • Consider Glycoprotein IIb/IIIa inhibitors for high-risk patients with positive troponin 4, 1

• Coronary Artery Bypass Grafting (CABG):

  • Continue aspirin
  • Discontinue clopidogrel 5-7 days before elective CABG
  • Discontinue intravenous GP IIb/IIIa inhibitors 4 hours before CABG
  • Manage anticoagulants appropriately: discontinue enoxaparin 12-24 hours before, fondaparinux 24 hours before, bivalirudin 3 hours before 4

Long-term Management

• Dual antiplatelet therapy for 12 months 1
• Beta-blockers (long-term)
• High-intensity statins regardless of cholesterol levels
• ACE inhibitors or ARBs for patients with:
  • Reduced left ventricular function
  • Hypertension
  • Diabetes 1

Common Pitfalls and Caveats

1. Delayed Diagnosis: Remember that up to 43.6% of NSTEMI patients present without chest pain, particularly elderly patients, women, and those with diabetes 1

2. Medication Interactions:

   • Clopidogrel effectiveness is reduced in CYP2C19 poor metabolizers
   • Avoid concomitant use of clopidogrel with omeprazole or esomeprazole 2

3. Bleeding Risk Assessment:

   • Higher risk in patients >75 years, weight <60 kg, prior bleeding history
   • Consider proton pump inhibitors for patients at high risk of gastrointestinal bleeding (except omeprazole/esomeprazole with clopidogrel) 1

4. Heart Failure Management:

   • Heart failure during NSTEMI is associated with poor prognosis
   • Beta-blockers have shown benefit even in Killip class II patients
   • ACE inhibitors show stronger evidence of benefit in patients with heart failure 5

5. Follow-up Planning:

   • Schedule follow-up appointments 1-2 weeks for high-risk patients
   • Monitor for bleeding complications with dual antiplatelet therapy 1