How should an acute ST-elevation myocardial infarction (STEMI) be managed?

Management of Acute STEMI

All patients with acute STEMI presenting within 12 hours of symptom onset require immediate reperfusion therapy—primary PCI is the preferred strategy if it can be performed within 120 minutes of STEMI diagnosis; otherwise, fibrinolytic therapy should be initiated immediately (within 10 minutes of diagnosis), preferably in the pre-hospital setting. 1

Initial Assessment and Diagnosis

Obtain and interpret a 12-lead ECG within 10 minutes of first medical contact to confirm STEMI diagnosis (ST-segment elevation in ≥2 contiguous leads). 1, 2 This should ideally occur in the pre-hospital setting with ECG transmission to the receiving PCI center while en route. 1

• Initiate continuous ECG monitoring with defibrillator capacity immediately 1
• Do NOT routinely administer oxygen unless oxygen saturation is <90% 1
• Assess for complications: heart failure, cardiogenic shock, ventricular arrhythmias, or cardiac arrest

Reperfusion Strategy Selection

The critical decision point is whether primary PCI can be achieved within 120 minutes of STEMI diagnosis:

Primary PCI Strategy (Preferred)

If door-to-balloon time ≤120 minutes:

• Transfer patient directly to catheterization laboratory, bypassing the emergency department 1
• Administer aspirin (oral or IV if unable to swallow) immediately 1
• Load with a potent P2Y12 inhibitor: prasugrel or ticagrelor (clopidogrel only if these are unavailable or contraindicated) 1
• Anticoagulation with unfractionated heparin (enoxaparin or bivalirudin are alternatives) 1
• Use radial artery access and drug-eluting stents as standard of care 1
• Do NOT use routine thrombus aspiration—this is contraindicated 1

Fibrinolytic Strategy

If primary PCI cannot be performed within 120 minutes:

• Initiate fibrinolysis within 10 minutes of STEMI diagnosis, preferably pre-hospital 1
• Use a fibrin-specific agent: tenecteplase, alteplase, or reteplase 1
  • For patients ≥75 years: use half-dose tenecteplase 1
  • For patients <75 years: use full dose 3
• Administer aspirin (oral or IV) 1
• Administer clopidogrel (not prasugrel or ticagrelor initially) 1
• Anticoagulation with enoxaparin IV followed by subcutaneous (preferred over unfractionated heparin) 1
  • Alternative: unfractionated heparin as weight-adjusted IV bolus followed by infusion 1
• Immediately transfer to PCI-capable center after fibrinolysis 1

Post-Fibrinolysis Management (Pharmacoinvasive Strategy)

After fibrinolytic administration, assess ST-segment resolution at 60-90 minutes:

• <50% ST-segment resolution = failed fibrinolysis: Perform immediate rescue PCI 1
• ≥50% ST-segment resolution = successful fibrinolysis: Perform angiography and PCI of infarct-related artery between 2-24 hours 1
• Emergency angiography immediately if: heart failure/shock, hemodynamic instability, electrical instability, worsening ischemia, or evidence of reocclusion 1

Special Populations

Cardiac arrest with STEMI on post-resuscitation ECG:

• Proceed with primary PCI strategy 1
• Initiate targeted temperature management for patients remaining unresponsive 1

Cardiogenic shock:

• Emergency angiography and PCI immediately 1
• Consider non-infarct-related artery PCI during index procedure 1

Maintenance Antithrombotic Therapy

Continue for 12 months post-PCI (unless excessive bleeding risk):

• Aspirin 75-100 mg daily 1
• Dual antiplatelet therapy: aspirin plus ticagrelor or prasugrel (or clopidogrel if others unavailable/contraindicated) 1
• After fibrinolysis, clopidogrel is the P2Y12 inhibitor of choice; consider switching to prasugrel/ticagrelor 48 hours after fibrinolysis if PCI performed 1

Additional Acute Management

Beta-blockers:

• Oral beta-blockers for patients with heart failure and/or LVEF <40% 1
• Avoid IV beta-blockers in hypotension, acute heart failure, AV block, or severe bradycardia 1

ACE inhibitors:

• Start within first 24 hours for patients with heart failure, LV dysfunction, diabetes, or anterior infarct 1

High-intensity statin:

• Initiate as early as possible and continue long-term 1
• Target LDL-C <1.8 mmol/L (70 mg/dL) or ≥50% reduction 1

PPI:

• Administer with DAPT in patients at high gastrointestinal bleeding risk 1

Critical Pitfalls to Avoid

• Do NOT delay reperfusion for routine echocardiography or additional testing
• Do NOT use fondaparinux for primary PCI 1
• Do NOT perform routine PCI of occluded infarct-related artery >48 hours after symptom onset in asymptomatic patients 1
• Do NOT use intra-aortic balloon pumps routinely in cardiogenic shock 4
• Do NOT cool patients pre-hospital with rapid infusion of large volumes of cold IV fluid after cardiac arrest 1

Post-Procedure Monitoring

• Monitor for at least 24 hours post-reperfusion 1
• Perform routine echocardiography during hospitalization to assess LV/RV function, detect mechanical complications, and exclude LV thrombus 1
• Early ambulation and discharge appropriate for uncomplicated patients 1