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

Workup and Treatment for NSTEMI

The management of NSTEMI requires immediate administration of dual antiplatelet therapy with aspirin (loading dose 250-500mg followed by 75-100mg daily) and a P2Y12 inhibitor, along with anticoagulation using low molecular weight heparin or unfractionated heparin, and an early invasive strategy within 24 hours for most patients. 1

Initial Workup

Diagnosis

• Perform 12-lead ECG within 10 minutes of first medical contact to differentiate NSTEMI from STEMI 1
• Obtain cardiac troponin measurements at 0 and 1-3 hours to confirm myocardial damage 1
• Begin continuous multi-lead ECG monitoring for arrhythmias 1
• Assess for risk factors, comorbidities, and potential contraindications to therapy
• Distinguish between Type 1 NSTEMI (atherothrombotic) and Type 2 NSTEMI (supply-demand mismatch) as management differs 2

Risk Stratification

• Calculate GRACE risk score to determine timing of invasive strategy 1
• High-risk features requiring immediate invasive strategy (<2 hours):
  • Hemodynamic instability
  • Recurrent/ongoing chest pain refractory to medical treatment
  • Life-threatening arrhythmias
  • Mechanical complications
  • Heart failure
  • Dynamic ST-T wave changes 1

Treatment

Immediate Pharmacological Management

1. Antiplatelet Therapy

   • Aspirin: 250-500mg loading dose, then 75-100mg daily indefinitely 1, 3
   • P2Y12 inhibitor (choose one):
     • Clopidogrel: 300mg loading dose, then 75mg daily 4
     • Ticagrelor: 180mg loading dose, then 90mg twice daily 3
     • Prasugrel: 60mg loading dose, then 10mg daily (only after coronary anatomy is known) 5

2. Anticoagulation (choose one):

   • Enoxaparin: 1mg/kg SC every 12 hours 1
   • Unfractionated heparin: 60-70 U/kg IV bolus, then 12-15 U/kg/hr 1
   • Fondaparinux or bivalirudin as alternatives 1

3. Anti-ischemic Therapy

   • Beta-blockers: Start within a few days if not initiated acutely 3
   • Nitroglycerin for ongoing chest pain 6
   • Morphine for pain relief if needed 6
   • Oxygen therapy if saturation <90% 6

Invasive Management Strategy

• Immediate invasive strategy (<2 hours): For patients with hemodynamic instability, refractory angina, heart failure, or life-threatening arrhythmias 1
• **Early invasive strategy (<24 hours)**: For patients with elevated troponin, dynamic ST/T changes, or GRACE score >140 1
• Delayed invasive strategy (<72 hours): For patients with diabetes, renal insufficiency, LVEF <40%, prior CABG, or GRACE score 109-140 1
• Consider GP IIb/IIIa inhibitors for high-risk patients undergoing PCI 1

Long-term Management

1. Dual Antiplatelet Therapy

   • Continue for 12 months in most patients 3, 1
   • For patients with bare-metal stents: minimum 1 month, ideally up to 12 months 3
   • For patients with drug-eluting stents: minimum 12 months 3

2. Secondary Prevention

   • Beta-blockers: Continue indefinitely unless contraindicated 3
   • ACE inhibitors/ARBs: Especially for patients with LVEF <40%, diabetes, hypertension 1
   • High-intensity statins: Start early and continue indefinitely 1
   • Risk factor modification: Smoking cessation, blood pressure control, diabetes management 1

Special Considerations

Surgical Patients

• Discontinue clopidogrel 5-7 days before CABG 1
• For patients requiring urgent CABG, consider platelet transfusion if bleeding risk is high

Comorbidities

• Diabetes: Monitor blood glucose levels frequently and avoid hypoglycemia 1
• Renal impairment: Adjust medication dosages, use low-osmolar contrast media 1
• Elderly patients: Higher risk of bleeding with antithrombotic therapy, consider dose adjustments 1
• Significant mitral regurgitation: Consider revascularization strategy as it improves outcomes 7

Follow-up

• Schedule follow-up appointments 1-2 weeks after discharge for high-risk patients 1
• Monitor for bleeding complications with dual antiplatelet therapy 1
• Consider proton pump inhibitors for patients at high risk of gastrointestinal bleeding 1

Common Pitfalls to Avoid

• Failing to distinguish between Type 1 and Type 2 NSTEMI, which require different management approaches 2
• Delaying invasive strategy in high-risk patients
• Premature discontinuation of dual antiplatelet therapy
• Inadequate secondary prevention measures
• Not recognizing and treating complications such as heart failure or arrhythmias