What is the initial treatment for Non-ST-Elevation Myocardial Infarction (NSTEMI)?

Initial Treatment for Non-ST-Elevation Myocardial Infarction (NSTEMI)

The initial treatment for NSTEMI should include aspirin, a P2Y12 receptor inhibitor (clopidogrel or ticagrelor), and anticoagulation therapy administered as soon as possible after hospital presentation, along with appropriate anti-ischemic medications. 1

Immediate Pharmacological Management

Antiplatelet Therapy

1. Aspirin

   • Administer immediately upon presentation and continue indefinitely in patients who tolerate it (Level of Evidence: A) 1
   • Initial dose: 162-325 mg non-enteric coated
   • Maintenance dose: 81-325 mg daily

2. P2Y12 Receptor Inhibitor (add to aspirin)

   • For conservative strategy (non-invasive approach):

     • Clopidogrel (loading dose 300-600 mg, then 75 mg daily) OR
     • Ticagrelor (loading dose 180 mg, then 90 mg twice daily)
     • Continue for up to 12 months (Level of Evidence: B) 1

   • For invasive strategy (early angiography planned):

     • Clopidogrel (600 mg loading dose as early as possible) OR
     • Ticagrelor (180 mg loading dose as early as possible) OR
     • Prasugrel (60 mg loading dose, but only at the time of PCI once coronary anatomy is defined) 1, 2

Anticoagulation

• Enoxaparin (preferred if no CABG planned within 24 hours)
  • 1 mg/kg subcutaneously every 12 hours (adjust for renal function)
• Unfractionated Heparin
  • 60 IU/kg IV bolus (maximum 4000 IU) followed by 12 IU/kg/hr infusion (maximum 1000 IU/hr)
• Fondaparinux
  • 2.5 mg subcutaneously daily (preferred in patients with increased bleeding risk) 1
• Bivalirudin
  • Consider if invasive strategy selected (especially with bleeding concerns) 1

GP IIb/IIIa Inhibitors

• Not routinely recommended upstream
• Consider adding eptifibatide or tirofiban in high-risk patients with recurrent ischemia despite standard therapy 1
• Should not use abciximab unless PCI is planned (Class III: Harm) 1

Anti-Ischemic Therapy

• Oxygen: 2-4 L/min if oxygen saturation <90% 3
• Nitroglycerin: Sublingual or IV for ongoing chest pain
• Beta-blockers: Start early in absence of contraindications
• Morphine: For pain unresponsive to nitrates (use with caution)

Risk Stratification and Treatment Strategy Decision

Early Invasive Strategy (within 24-48 hours)

Indicated for high-risk features:

• Recurrent angina/ischemia at rest despite treatment
• Elevated cardiac troponin
• New ST-segment depression
• Heart failure or hemodynamic instability
• Sustained ventricular arrhythmias
• GRACE score >140 1

Conservative Strategy

Consider for low-risk patients:

• No recurrent symptoms
• No heart failure
• No arrhythmias
• Normal or near-normal troponin levels
• No new ST-segment changes 1

Important Considerations and Pitfalls

1. Timing of P2Y12 inhibitor administration:

   • For patients likely to undergo CABG, delay clopidogrel/ticagrelor if possible
   • Do not administer prasugrel before coronary anatomy is known due to increased bleeding risk if CABG is needed 2

2. Weight considerations:

   • For patients <60 kg on prasugrel, consider lower maintenance dose (5 mg) due to increased bleeding risk 2

3. Age considerations:

   • Prasugrel generally not recommended in patients ≥75 years due to increased bleeding risk 2

4. Contraindications:

   • Prasugrel contraindicated in patients with prior stroke or TIA 2
   • Avoid GP IIb/IIIa inhibitors in patients with active bleeding 1

5. Monitoring:

   • Serial ECGs and cardiac biomarkers for patients with initially negative results
   • Watch for recurrent symptoms that may necessitate change in strategy 1

The evidence strongly supports early dual antiplatelet therapy and anticoagulation as the cornerstone of initial NSTEMI management, with the decision between invasive versus conservative strategies based on risk stratification. This approach has been shown to reduce mortality and recurrent ischemic events 4.