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

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

The management of NSTEMI requires immediate dual antiplatelet therapy with aspirin and a P2Y12 inhibitor, anticoagulation, and risk stratification to determine the timing of invasive strategy, followed by appropriate secondary prevention measures. 1

Initial Management

Immediate Interventions

• Aspirin: Administer 162-325 mg loading dose (non-enteric coated, chewed or crushed) followed by 81 mg daily maintenance 1
• Anticoagulation: Start one of the following immediately:
  • Unfractionated heparin (UFH): IV bolus and infusion for at least 48 hours or until PCI 2
  • Enoxaparin: 1 mg/kg SC every 12 hours for duration of hospitalization up to 8 days 2, 1
  • Fondaparinux: For patients with high bleeding risk 1
  • Bivalirudin: Alternative to heparin, especially in patients with heparin-induced thrombocytopenia 1

P2Y12 Inhibitor Selection

• Ticagrelor: Preferred for moderate to high-risk patients (180 mg loading dose followed by 90 mg twice daily) 1
• Clopidogrel: 300-600 mg loading dose (600 mg preferred for planned invasive strategy) followed by 75 mg daily 1, 3
• Prasugrel: Only after coronary anatomy is defined and PCI is planned (60 mg loading dose followed by 10 mg daily) 1, 4

Risk Stratification

High-Risk Features (requiring early invasive strategy within 24 hours)

• Recurrent ischemia
• Elevated troponins
• Dynamic ST changes
• Diabetes mellitus
• High GRACE or TIMI scores
• LVEF ≤ 0.40 2

Very High-Risk Features (requiring immediate invasive strategy < 2 hours)

• Severe ongoing ischemia
• Major arrhythmias
• Hemodynamic instability 1

Management Strategy Based on Risk

Invasive Strategy

For high-risk patients:

1. Continue aspirin 2
2. Administer P2Y12 inhibitor loading dose if not given before diagnostic angiography 2
3. For troponin-positive patients, administer IV GP IIb/IIIa inhibitor (abciximab, eptifibatide, or tirofiban) if not started before diagnostic angiography 2
4. Proceed with PCI or CABG as appropriate based on coronary anatomy 2

Conservative Strategy

For lower-risk patients:

1. Continue aspirin and P2Y12 inhibitor 2
2. Continue anticoagulation for duration of hospitalization (up to 8 days) 2
3. Measure LVEF 2
4. If LVEF > 0.40, perform stress test 2
5. If stress test shows high-risk features, proceed to diagnostic angiography 2

Special Considerations

For Patients Undergoing PCI

• Continue aspirin 2
• Ensure P2Y12 inhibitor loading has been administered 2
• Consider GP IIb/IIIa inhibitor for high-risk patients 2
• Discontinue anticoagulant therapy after uncomplicated PCI 2

For Patients Undergoing CABG

• Continue aspirin 2
• Discontinue clopidogrel 5-7 days before elective CABG 2, 1
• Discontinue prasugrel at least 7 days prior to CABG 4
• Discontinue ticagrelor 3-5 days before CABG 1
• Discontinue GP IIb/IIIa inhibitors 4 hours before CABG 2
• Manage anticoagulants appropriately:
  • Continue UFH 2
  • Discontinue enoxaparin 12-24 hours before CABG 2
  • Discontinue fondaparinux 24 hours before CABG 2
  • Discontinue bivalirudin 3 hours before CABG 2

Secondary Prevention

• Antiplatelet therapy:
  • Continue aspirin indefinitely 2, 1
  • Continue P2Y12 inhibitor for at least 1 month and ideally up to 12 months 2, 1
• Lipid management: High-intensity statin therapy 1
• Blood pressure control: Beta-blockers and ACE inhibitors/ARBs 1, 5
• For patients with heart failure: Consider eplerenone for patients with LVEF ≤ 40% and heart failure or diabetes 5

Pitfalls and Caveats

1. Bleeding risk: P2Y12 inhibitors increase bleeding risk. Monitor hemoglobin and platelet counts daily during GP IIb/IIIa inhibitor administration 2, 1

2. Prasugrel contraindications: Not recommended for patients ≥75 years or <60 kg due to increased bleeding risk 4

3. Clopidogrel resistance: Consider alternative P2Y12 inhibitor in patients who are CYP2C19 poor metabolizers 3

4. NSAIDs: Discontinue all NSAIDs except aspirin due to increased risks of mortality and reinfarction 1

5. Timing of invasive strategy: Delay may be appropriate for some patients, but those with ongoing ischemia, hemodynamic instability, or life-threatening arrhythmias require immediate intervention 1

6. Anticoagulation duration: For medically managed patients, continue anticoagulation for the duration of hospitalization (up to 8 days) 6

The management of NSTEMI has evolved significantly with newer antiplatelet and anticoagulant options. Risk stratification remains crucial in determining the optimal timing of invasive management and medication selection.