Immediate Management of Non-ST-Elevation Myocardial Infarction (NSTEMI)
The immediate management of NSTEMI requires dual antiplatelet therapy with aspirin plus a P2Y12 inhibitor, anticoagulation, and risk stratification to determine timing of invasive strategy, with early invasive approach (within 24 hours) recommended for high-risk patients. 1
Initial Assessment and Stabilization
- Obtain 12-lead ECG within 10 minutes of first medical contact 2
- Administer loading dose of aspirin 150-300mg followed by 75-100mg daily maintenance 2
- Obtain cardiac troponin levels (results should be available within 60 minutes) 2
- Risk stratify patient using validated risk scores (TIMI or GRACE) to guide management decisions 2
Antiplatelet Therapy
P2Y12 Inhibitor Loading Dose
One of the following regimens should be used:
- Clopidogrel 600 mg as early as possible before or at the time of PCI 1
- Prasugrel 60 mg promptly and no later than 1 hour after PCI once coronary anatomy is defined (contraindicated in patients with prior stroke/TIA) 1, 3
- Ticagrelor 180 mg as early as possible before or at the time of PCI 1
Maintenance Therapy
- Aspirin should be continued indefinitely 1
- P2Y12 inhibitor should be continued for at least 12 months 1:
- Clopidogrel 75 mg daily
- Prasugrel 10 mg daily (5 mg if weight <60 kg)
- Ticagrelor 90 mg twice daily (with aspirin 81 mg daily)
Anticoagulation
Choose one of the following anticoagulants 1:
- Enoxaparin: 1 mg/kg SC every 12 hours (reduce to once daily if CrCl <30 mL/min)
- Bivalirudin: 0.10 mg/kg loading dose followed by 0.25 mg/kg/hour (for early invasive strategy)
- Fondaparinux: 2.5 mg SC daily (requires additional anticoagulant with anti-IIa activity if PCI is performed)
- Unfractionated heparin: 60 IU/kg IV loading dose (max 4000 IU) with 12 IU/kg/hour infusion (max 1000 IU/hour)
Invasive vs. Conservative Strategy
Urgent/Immediate Invasive Strategy (<2 hours)
Indicated for patients with 1, 2:
- Refractory angina
- Hemodynamic instability
- Electrical instability
- Life-threatening arrhythmias
Early Invasive Strategy (within 24 hours)
Recommended for high-risk patients with 1:
- Elevated troponin
- Dynamic ECG changes
- High GRACE score
Delayed Invasive Strategy (24-72 hours)
Appropriate for intermediate-risk patients 1
Ischemia-Guided (Conservative) Strategy
May be considered for low-risk patients or those with contraindications to invasive procedures 1
Additional Pharmacotherapy
Beta-Blockers
- Administer if patient is tachycardic or hypertensive without signs of heart failure 1, 2
- Metoprolol: Start with three 5mg IV boluses at 2-minute intervals, followed by 50mg orally every 6 hours, then 100mg twice daily maintenance 2
- Avoid in patients with marked first-degree AV block, second/third-degree AV block, asthma, severe LV dysfunction, or high risk for cardiogenic shock 1
Nitrates
- For symptom relief 2
- Avoid in patients with hypotension, right ventricular infarction, or recent use of phosphodiesterase inhibitors
GP IIb/IIIa Inhibitors
- Consider adding eptifibatide or tirofiban in high-risk patients, especially with delayed angiography 1
- Abciximab should not be administered to patients in whom PCI is not planned 1, 2
Common Pitfalls and Caveats
Do not administer fibrinolytic therapy in NSTEMI patients 1
Prasugrel is contraindicated in patients with prior history of stroke or TIA 1, 3
Timing of P2Y12 inhibitor loading:
Weight considerations:
- For patients <60 kg, consider reducing prasugrel maintenance dose to 5 mg daily due to increased bleeding risk 3
Fondaparinux limitation:
- If PCI is performed while on fondaparinux, additional anticoagulant with anti-IIa activity (UFH or bivalirudin) must be administered due to risk of catheter thrombosis 1
By following this algorithm for immediate NSTEMI management, you can optimize outcomes while minimizing complications. The strategy should be tailored based on risk stratification, with higher-risk patients benefiting most from an early invasive approach.