Management of Non-ST-Elevation Myocardial Infarction (NSTEMI)
The management of NSTEMI requires immediate administration of aspirin (162-325 mg), anticoagulation with unfractionated heparin, and risk stratification to determine whether an early invasive or conservative strategy is appropriate, followed by dual antiplatelet therapy and secondary prevention measures. 1
Initial Management
- Administer aspirin 162-325 mg (non-enteric formulation, orally or chewed) immediately upon presentation 2
- Admit to a monitored unit with continuous rhythm monitoring for at least 24 hours 2
- Administer supplemental oxygen if arterial oxygen saturation is <90% 2
- Consider nitroglycerin for ongoing ischemic symptoms unless contraindicated (systolic BP <90 mmHg, severe bradycardia, tachycardia without heart failure, right ventricular infarction, or recent phosphodiesterase inhibitor use) 2
- Initiate beta-blockers to reduce myocardial oxygen demand by decreasing heart rate, blood pressure, and myocardial contractility 2, 3
Antiplatelet Therapy
- Continue aspirin indefinitely (Level of Evidence: A) 1
- Administer a loading dose of clopidogrel (300 mg) if an early conservative strategy is selected or if PCI is planned and not started before diagnostic angiography (Level of Evidence: A) 1, 4
- For patients undergoing PCI, prasugrel (60 mg loading dose, 10 mg daily maintenance) may be considered as an alternative to clopidogrel, but is contraindicated in patients with prior stroke or TIA 5
- Avoid NSAIDs (except aspirin) during hospitalization due to increased risks of mortality, reinfarction, hypertension, heart failure, and myocardial rupture 2
Anticoagulant Therapy
- Administer unfractionated heparin (UFH), enoxaparin, fondaparinux, or bivalirudin 1
- For patients managed medically:
- Continue intravenous UFH for at least 48 hours or until discharge if given before diagnostic angiography (Level of Evidence: A) 1
- Continue enoxaparin for duration of hospitalization, up to 8 days, if given before diagnostic angiography (Level of Evidence: A) 1
- Continue fondaparinux for duration of hospitalization, up to 8 days, if given before diagnostic angiography (Level of Evidence: B) 1
Management Strategy Selection
Early Invasive Strategy (angiography within 24-48 hours)
Indicated for patients with:
- Refractory angina 1
- Hemodynamic or electrical instability 1
- Elevated cardiac biomarkers 1
- High GRACE or TIMI risk score 2, 6
Conservative Strategy
Appropriate for:
- Lower-risk patients without ongoing ischemia 2
- Patients with significant comorbidities where risks of invasive approach outweigh benefits 2
Post-Angiography Management
If PCI is selected:
- Continue aspirin (Level of Evidence: A) 1
- Administer a loading dose of P2Y12 inhibitor if not started before diagnostic angiography (Level of Evidence: A) 1
- Consider GP IIb/IIIa inhibitor for troponin-positive and other high-risk patients (Level of Evidence: A) 1
- Discontinue anticoagulant therapy after PCI for uncomplicated cases (Level of Evidence: B) 1
If CABG is selected:
- Continue aspirin (Level of Evidence: A) 1
- Discontinue clopidogrel 5-7 days before elective CABG (Level of Evidence: B) 1
- Discontinue prasugrel at least 7 days before CABG 5
- Discontinue GP IIb/IIIa inhibitors 4 hours before CABG (Level of Evidence: B) 1
- For anticoagulants:
If medical therapy is selected:
- Continue aspirin (Level of Evidence: A) 1
- Administer a loading dose of clopidogrel if not given before diagnostic angiography (Level of Evidence: A/B) 1
- Discontinue GP IIb/IIIa inhibitor if started previously (Level of Evidence: B) 1
- Continue anticoagulant therapy as outlined above 1
Long-term Management
- Measure left ventricular ejection fraction (LVEF) (Level of Evidence: B) 1
- If LVEF ≤0.40, consider diagnostic angiography (Level of Evidence: B) 1
- If LVEF >0.40, consider a stress test (Level of Evidence: B) 1
- Initiate ACE inhibitors for patients with heart failure, LV dysfunction (LVEF <0.40), hypertension, or diabetes 2, 3
- Consider ARBs for ACE inhibitor-intolerant patients 2
- Implement aggressive risk factor modification and secondary prevention measures 7
Common Pitfalls and Caveats
- Avoid immediate-release dihydropyridine calcium channel blockers without adequate beta-blockade 2
- Avoid intravenous ACE inhibitors within the first 24 hours due to increased risk of hypotension 2
- Patients who have received nitrates must not take PDE5 inhibitors (sildenafil within 24 hours, tadalafil within 48 hours) due to potentially dangerous hypotensive effects 2
- Type 2 NSTEMI (supply-demand mismatch without plaque rupture) requires treatment of the underlying cause rather than focusing solely on antithrombotic therapy 8
- For patients with Type 1 NSTEMI (plaque rupture), dual antiplatelet therapy and consideration of early invasive strategy are paramount 8