What are the latest guidelines for managing patients with ST-Elevation Myocardial Infarction (STEMI) or Non-ST-Elevation Myocardial Infarction (NSTEMI)?

STEMI and NSTEMI Management: Latest Guidelines

STEMI Management

Primary PCI is the preferred reperfusion strategy when performed within 120 minutes of STEMI diagnosis (first medical contact-to-device time), with immediate transfer to a 24/7 high-volume PCI center bypassing the emergency department. 1

Reperfusion Strategy Selection

• Time-critical decision: If primary PCI cannot be achieved within 120 minutes of STEMI diagnosis, initiate fibrinolytic therapy immediately (within 10 minutes of diagnosis) 1
• For patients <75 years with large anterior infarction presenting within 2 hours of symptom onset, the PCI window narrows to 90 minutes 1
• STEMI diagnosis requires ST-elevation ≥0.1 mV in at least two contiguous leads or new/presumed new left bundle branch block 2
• Critical distinction: Patients with bundle branch block, ventricular pacing, hyperacute T-waves, or isolated ST-depression in anterior leads with ongoing ischemic symptoms should follow a primary PCI strategy 1

Immediate Pharmacotherapy

Dual antiplatelet therapy with aspirin plus a potent P2Y12 inhibitor (ticagrelor or prasugrel preferred over clopidogrel) must be administered before or at the time of PCI. 2

• Aspirin: 150-300 mg loading dose, then 75-100 mg daily indefinitely 3
• P2Y12 inhibitor selection:
  • Prasugrel: 60 mg loading dose at time of PCI (once anatomy defined), then 10 mg daily for 12 months 1, 4
  • Ticagrelor: 180 mg loading dose, then 90 mg twice daily for 12 months 1
  • Clopidogrel: 600 mg loading dose only if prasugrel/ticagrelor contraindicated, then 75 mg daily 1

Anticoagulation During PCI

• Unfractionated heparin is standard, with enoxaparin or bivalirudin as alternatives 1
• Bivalirudin may be preferred in patients with high bleeding risk and should be continued for several hours post-PCI 1
• Routine thrombus aspiration is contraindicated 1

Technical Considerations

• Radial access and drug-eluting stents are the standard of care during primary PCI 1
• Routine deferred stenting is contraindicated 1
• Non-infarct-related artery lesions: Treat severe stenosis before hospital discharge (immediately or staged) in stable patients; consider immediate treatment in cardiogenic shock 1

Post-Reperfusion Management

• ACE inhibitors: Initiate within 24 hours for all patients, particularly those with anterior MI, heart failure, LVEF ≤0.40, hypertension, or diabetes; continue indefinitely 2, 1
• Beta-blockers: Start in all eligible patients and continue indefinitely 1, 2
• High-intensity statin therapy: Initiate before discharge regardless of baseline LDL 5
• Monitor for at least 24 hours post-reperfusion; early ambulation and discharge appropriate for uncomplicated patients 1

Special Population Considerations

Prasugrel is generally not recommended in patients ≥75 years due to increased fatal and intracranial bleeding risk, except in high-risk situations (diabetes or prior MI). 4

• Contraindications to prasugrel: Prior stroke/TIA (absolute), age ≥75 years (relative), weight <60 kg (consider 5 mg maintenance dose) 4
• Pregnant women: Primary PCI strongly preferred over fibrinolysis to minimize fetal radiation and diagnose potential coronary dissection 2
• Emergency CABG indicated for failed PCI with persistent pain/hemodynamic instability or cardiogenic shock in patients <75 years when performed within 18 hours of shock onset 2

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NSTEMI Management

An early invasive strategy (diagnostic angiography with intent to revascularize) within 12-24 hours is indicated for high-risk NSTEMI patients, defined by elevated troponin, refractory angina, hemodynamic/electrical instability, or GRACE score ≥140. 1, 3

Risk Stratification and Timing

• High-risk features requiring early invasive approach (within 12-24 hours): 1

  • Elevated high-sensitivity cardiac troponin
  • Refractory angina despite medical therapy
  • Hemodynamic instability or cardiogenic shock
  • Life-threatening arrhythmias
  • GRACE score ≥140
  • Mechanical complications of MI

• Low-to-intermediate risk patients: Delayed invasive approach (within 24-72 hours) is reasonable 1

• Conservative strategy may be considered for initially stabilized patients with elevated risk, based on physician and patient preference, though this represents a weaker recommendation 1

Antiplatelet Therapy

Aspirin 162-325 mg loading dose immediately, then 75-162 mg daily indefinitely, plus a P2Y12 inhibitor before diagnostic angiography. 1, 3

P2Y12 Inhibitor Selection Strategy:

Before PCI (upstream therapy):

• Clopidogrel: 300-600 mg loading dose, then 75 mg daily 1, 3
• Ticagrelor: 180 mg loading dose, then 90 mg twice daily 1, 3
• IV GP IIb/IIIa inhibitor (eptifibatide or tirofiban preferred) 1

At time of PCI:

• Prasugrel: 60 mg loading dose (once anatomy defined and PCI decision made), then 10 mg daily 1, 4
• Ticagrelor: 180 mg loading dose if not given upstream, then 90 mg twice daily 1
• Clopidogrel: 600 mg loading dose if not started before PCI, then 75 mg daily 1

Duration: Continue P2Y12 inhibitor for at least 12 months unless bleeding risk outweighs benefit 1, 3

Anticoagulation

Parenteral anticoagulation is mandatory for all NSTEMI patients in addition to antiplatelet therapy, continued for at least 48 hours or until revascularization. 5, 3

• Options: Unfractionated heparin, enoxaparin, fondaparinux, or bivalirudin 5, 3
• Bivalirudin may be used as alternative to heparin plus GP IIb/IIIa inhibitor during PCI 1

Conservative Strategy Patients

For patients managed conservatively who develop recurrent symptoms, heart failure, or serious arrhythmias:

• Proceed to diagnostic angiography 1
• Add either IV GP IIb/IIIa inhibitor (eptifibatide or tirofiban), clopidogrel loading dose, or ticagrelor loading dose to aspirin and anticoagulation before angiography 1

Post-Catheterization Long-Term Management

• Dual antiplatelet therapy: Continue for 12 months post-PCI with aspirin plus P2Y12 inhibitor 5, 3
• ACE inhibitors: Initiate and continue indefinitely for patients with heart failure, LV dysfunction (LVEF <0.40), hypertension, or diabetes 3, 1
• Beta-blockers: Indicated for all patients recovering from NSTEMI unless contraindicated; continue indefinitely 3, 1
• High-intensity statin therapy: Initiate before discharge regardless of baseline LDL 5
• Aldosterone blockade: For patients with LVEF ≤0.40 and either diabetes or heart failure, without significant renal dysfunction or hyperkalemia, already on therapeutic ACE inhibitor dose 1

Critical Pitfalls to Avoid

Do not administer prasugrel before coronary anatomy is defined in NSTEMI patients—this increases bleeding risk without clear benefit, particularly if urgent CABG is needed. 1, 4

• Prasugrel is contraindicated in patients with prior stroke/TIA (any time in history) 4
• In patients ≥75 years receiving prasugrel, reduce maintenance dose to 5 mg daily if used 4
• In patients <60 kg, consider reducing prasugrel maintenance dose to 5 mg daily due to increased bleeding risk 4
• Discontinue clopidogrel 5-7 days before elective CABG; prasugrel should be stopped at least 7 days prior to any surgery 3, 4
• An early invasive strategy is not recommended in patients with extensive comorbidities (liver/pulmonary failure, cancer) where revascularization risks outweigh benefits 1