What is the immediate management for a patient presenting with Acute Coronary Syndrome (ACS) Non-ST-Elevation Myocardial Infarction (NSTEMI)?

Immediate Management of NSTEMI

Initiate dual antiplatelet therapy with aspirin (162-325 mg loading dose, then 81 mg daily) plus a P2Y12 inhibitor (clopidogrel 300 mg loading dose then 75 mg daily, or ticagrelor 180 mg loading then 90 mg twice daily), combined with parenteral anticoagulation (enoxaparin 1 mg/kg SC every 12 hours, or UFH, or fondaparinux 2.5 mg SC daily), and proceed with risk stratification to determine timing of invasive coronary angiography. 1, 2

Initial Antiplatelet Therapy

• Aspirin should be administered immediately to all patients without contraindications 1, 2
• Add a P2Y12 inhibitor in conjunction with aspirin for dual antiplatelet therapy (DAPT) 1, 2
  • Clopidogrel: 300 mg loading dose followed by 75 mg once daily (note: reduced efficacy in CYP2C19 poor metabolizers—consider alternative P2Y12 inhibitor if genetic testing reveals poor metabolizer status) 1, 2
  • Ticagrelor: 180 mg loading dose followed by 90 mg twice daily (with aspirin maintenance dose of 81 mg daily) 1
  • Prasugrel: 60 mg loading dose followed by 10 mg daily (only for patients proceeding to PCI; contraindicated in patients with prior stroke/TIA) 1

Parenteral Anticoagulation

Select one anticoagulant based on bleeding risk and invasive strategy timing: 1

• Enoxaparin: 1 mg/kg SC every 12 hours (reduce to 1 mg/kg SC once daily if CrCl <30 mL/min); continue for duration of hospitalization or until PCI; optional 30 mg IV loading dose 1
• Fondaparinux: 2.5 mg SC daily; continue for duration of hospitalization or until PCI; critical caveat: must add UFH or bivalirudin during PCI due to catheter thrombosis risk 1
• UFH: 60 IU/kg IV bolus (max 4000 IU) followed by 12 IU/kg/hour infusion (max 1000 IU/hour); adjust per aPTT per hospital protocol; continue for 48 hours or until PCI 1
• Bivalirudin: 0.10 mg/kg loading dose followed by 0.25 mg/kg/hour (only for early invasive strategy); continue until angiography or PCI with provisional GP IIb/IIIa inhibitor use 1

Risk Stratification and Invasive Strategy Timing

Determine urgency of coronary angiography based on clinical risk features: 1

Very High-Risk (Immediate Invasive Strategy <2 hours):

• Hemodynamic instability or cardiogenic shock 1
• Refractory or recurrent chest pain despite medical therapy 1
• Life-threatening arrhythmias or cardiac arrest 1
• Mechanical complications of MI (papillary muscle rupture, ventricular septal defect, free wall rupture) 1
• Acute heart failure with refractory angina or ST-segment deviation 1

High-Risk (Early Invasive Strategy <24 hours):

• Elevated cardiac troponin compatible with MI 1
• Dynamic ST-segment or T-wave changes (symptomatic or silent) 1
• GRACE risk score >140 1

Intermediate-Risk (Invasive Strategy <72 hours):

• Diabetes mellitus 1
• Renal insufficiency (eGFR <60 mL/min/1.73 m²) 1
• LVEF <40% or congestive heart failure 1
• Early post-infarction angina 1
• Recent PCI or prior CABG 1
• GRACE risk score 109-140 1

Low-Risk (Ischemia-Guided Strategy):

• Patients without high or intermediate-risk features may be managed with an ischemia-guided approach involving noninvasive stress testing 1

Anti-Ischemic Therapy

• Oxygen: Administer only if arterial saturation <90%, respiratory distress, or signs of hypoxemia present 3
• Nitroglycerin: Sublingual or IV for symptom relief 3
• Beta-blockers: Initiate to reduce myocardial oxygen consumption unless contraindicated by heart failure, low-output state, or cardiogenic shock risk 3

Critical Contraindications and Precautions

• Fibrinolytic therapy is contraindicated in NSTEMI (Class III: Harm) 1
• Avoid NSAIDs (except aspirin) during hospitalization due to increased mortality, reinfarction, hypertension, heart failure, and myocardial rupture risk 3
• Avoid omeprazole and esomeprazole with clopidogrel as they significantly reduce antiplatelet activity via CYP2C19 inhibition 2
• GP IIb/IIIa inhibitors: Routine upstream use not recommended; reserve for provisional use during PCI or high-risk features 1

Duration of Dual Antiplatelet Therapy

• Medically managed patients: Continue DAPT (aspirin + P2Y12 inhibitor) for up to 12 months 1
• Patients receiving PCI with stenting: Continue DAPT for at least 12 months (applies to both bare-metal and drug-eluting stents) 1
• Aspirin: Continue indefinitely 1

Additional Considerations

• Screen for diabetes and monitor glucose levels frequently 1
• Assess renal function by eGFR in all patients to guide anticoagulant dosing 1
• Measure LVEF in all NSTEMI patients for prognostic stratification 3
• Initiate statin therapy early (within 1-4 days) with high-intensity regimen (e.g., atorvastatin 80 mg) targeting LDL-C <70 mg/dL 1
• ACE inhibitors: Initiate within 24 hours in patients with LVEF ≤40%, heart failure, diabetes, hypertension, or chronic kidney disease 1