What is the management approach for ST-Elevation Myocardial Infarction (STEMI)?

Management of ST-Elevation Myocardial Infarction (STEMI)

Primary percutaneous coronary intervention (PCI) is the recommended reperfusion strategy for STEMI patients when it can be performed within 90 minutes of first medical contact or within 120 minutes for patients presenting to non-PCI capable facilities. 1, 2

Initial Assessment and Management

• Administer 162-325 mg of non-enteric coated aspirin immediately upon first medical contact 3, 2
• Perform a 12-lead ECG and have it interpreted by an experienced physician within 10 minutes of emergency department arrival 2
• If initial ECG is non-diagnostic but clinical suspicion remains high, obtain serial ECGs at 5-10 minute intervals 2
• For inferior STEMI, obtain right-sided ECG leads to screen for right ventricular infarction 2
• Administer supplemental oxygen only to maintain arterial saturation >90% in patients with hypoxemia or pulmonary congestion 1, 3
• Provide morphine sulfate for patients with ongoing ischemic pain or pulmonary congestion 1, 4
• Initiate oral beta-blocker therapy promptly in patients without contraindications (heart failure, hypotension, bradycardia) 3, 4

Reperfusion Strategy Decision-Making

• The critical decision point is whether primary PCI can be performed within 120 minutes of first medical contact 1, 2
• For patients presenting within 12 hours of symptom onset without contraindications, immediate reperfusion therapy is indicated 1
• Every community should have a written protocol guiding EMS personnel in determining where to take STEMI patients 2

Primary PCI Strategy

• Preferred reperfusion strategy when performed within 90 minutes of first medical contact 1, 2
• Administer dual antiplatelet therapy before PCI, including aspirin and a P2Y12 inhibitor (prasugrel, ticagrelor, or clopidogrel if others unavailable) 1, 4
• For patients receiving stents, continue dual antiplatelet therapy for at least 12 months 1, 3
• Patients should be transferred directly to the catheterization laboratory, bypassing the emergency department 1

Fibrinolytic Strategy

• If primary PCI cannot be performed within 120 minutes of first medical contact, administer fibrinolytic therapy within 30 minutes of hospital arrival 3, 2
• Use a fibrin-specific agent (tenecteplase, alteplase, or reteplase) 1
• Transfer to a PCI-capable center immediately after fibrinolysis 1
• Perform rescue PCI immediately if fibrinolysis fails (<50% ST-segment resolution at 60-90 minutes) or in the presence of hemodynamic/electrical instability 1

Pharmacotherapy

• Antiplatelet therapy:

  • Aspirin 162-325 mg loading dose followed by 75-100 mg daily indefinitely 1, 3
  • P2Y12 inhibitor (prasugrel, ticagrelor, or clopidogrel) for 12 months 1, 5
  • Prasugrel is contraindicated in patients with history of stroke/TIA and generally not recommended in patients ≥75 years 5

• Anticoagulation:

  • For primary PCI: Unfractionated heparin, enoxaparin, or bivalirudin 1, 6
  • For fibrinolysis: Enoxaparin (preferred) or unfractionated heparin 1

• Additional medications:

  • ACE inhibitors within 24 hours in patients with anterior STEMI, heart failure, or LVEF ≤0.40 1, 2
  • Beta-blockers for all eligible patients without contraindications 1, 3
  • High-intensity statin therapy for all patients without contraindications 4, 2
  • Aldosterone blockade for patients with LVEF ≤0.40 and either symptomatic heart failure or diabetes 1

Management of Complications

Cardiogenic Shock

• Emergency revascularization (PCI or CABG) is recommended regardless of time delay from MI onset 1, 4
• Intra-aortic balloon counterpulsation is recommended for patients when shock is not quickly reversed with pharmacological therapy 1, 4
• Consider circulatory support with inotropic and vasopressor agents 1

Heart Failure/Pulmonary Edema

• Administer diuretics (furosemide, torsemide, or bumetanide) if volume overload is present 1
• Initiate ACE inhibitors with low initial dose (e.g., captopril 1-6.25 mg) unless systolic BP <100 mmHg 1
• Administer nitrates unless systolic BP <100 mmHg 1
• Perform echocardiography urgently to assess LV and RV function and exclude mechanical complications 1

Mechanical Complications

• Ventricular septal rupture, free wall rupture, and papillary muscle rupture require urgent surgical consultation 2
• Echocardiography should be performed urgently to diagnose these complications 1

Post-STEMI Care

• Continue dual antiplatelet therapy for at least 12 months in patients receiving stents 1, 3
• Initiate or continue high-intensity statin therapy 4, 2
• Cardiac rehabilitation is recommended for all patients 1
• Smoking cessation counseling with offers of support, nicotine replacement therapies, varenicline, and bupropion 1

Common Pitfalls and Caveats

• Do not delay reperfusion therapy to wait for cardiac biomarker results 2
• Avoid immediate-release nifedipine due to reflex sympathetic activation, tachycardia, and hypotension 2
• Do not administer beta-blockers or calcium channel blockers to patients with frank cardiac failure, pulmonary congestion, or signs of low-output state 1, 4
• When possible, discontinue prasugrel at least 7 days prior to any surgery to reduce bleeding risk 5
• Time is critical - delays in reperfusion therapy are associated with worse outcomes 7, 6