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

Treatment of ST-Elevation Myocardial Infarction (STEMI)

Primary percutaneous coronary intervention (PCI) performed within 90-120 minutes of first medical contact is the definitive treatment for STEMI and should be pursued for all patients when feasible. 1

Immediate Actions at First Medical Contact

• Obtain a 12-lead ECG within 10 minutes of first medical contact and initiate continuous ECG monitoring with defibrillator capacity 1
• Administer aspirin 150-325 mg orally (chewable) or 250-500 mg IV immediately if unable to swallow 2, 1
• Avoid routine oxygen therapy unless oxygen saturation is <90% 1
• Administer morphine sulfate for pain control and anxiety reduction, which also reduces sympathetic drive and myocardial oxygen demand 2, 3

Reperfusion Strategy Selection

The choice between primary PCI and fibrinolysis depends entirely on time to treatment:

Primary PCI Strategy (Preferred)

• Primary PCI is the preferred reperfusion method when it can be performed within 90 minutes (door-to-balloon) at PCI-capable hospitals or within 120 minutes from first medical contact for patients requiring transfer 2, 1
• Transfer patients directly to the catheterization laboratory, bypassing the emergency department 1
• Administer a potent P2Y12 inhibitor before or at the time of PCI: prasugrel 60 mg loading dose or ticagrelor 180 mg loading dose (preferred over clopidogrel 600 mg) 1, 4
• Provide anticoagulation with unfractionated heparin as IV bolus at 100 U/kg (60 U/kg if GPIIb/IIIa inhibitors are used) 1
• Use radial access and drug-eluting stents as standard of care 1
• Do NOT perform routine thrombus aspiration or deferred stenting 1

Fibrinolytic Strategy

Fibrinolytic therapy should be initiated within 30 minutes of hospital arrival when primary PCI cannot be performed within 120 minutes, particularly for patients presenting within 3 hours of symptom onset 2

• Administer a fibrin-specific agent: tenecteplase (single weight-adjusted bolus 0.53 mg/kg, maximum 50 mg), alteplase, or reteplase 1
• For patients ≥75 years old, reduce tenecteplase dose by 50% to minimize stroke risk 1
• Add clopidogrel 300 mg loading dose (75 mg if age >75 years) to aspirin 1
• Provide anticoagulation with enoxaparin (30 mg IV bolus followed by 1 mg/kg subcutaneous every 12 hours) or unfractionated heparin for at least 48 hours and up to 8 days 1
• Immediately transfer all fibrinolysis-treated patients to a PCI-capable center for angiography within 2-24 hours after successful fibrinolysis 2, 1

Rescue PCI

• Perform emergency rescue PCI for patients with failed fibrinolysis (persistent chest pain, <50% ST-segment resolution at 60-90 minutes, or hemodynamic instability) 2

Special Populations

Cardiogenic Shock

• Perform emergency angiography and PCI immediately regardless of time from symptom onset 1
• Insert intra-aortic balloon pump for hemodynamic stabilization 2

Late Presentation (>12 hours)

• Primary PCI is still recommended for patients with ongoing symptoms, hemodynamic instability, or electrical instability even beyond 12 hours 2
• Stable patients presenting 12-48 hours after symptom onset should NOT receive fibrinolysis but may benefit from urgent catheterization 2

Mechanical Complications

• Ventricular septal rupture, acute mitral regurgitation from papillary muscle rupture, or free wall rupture require urgent cardiac surgical repair with concomitant CABG 2
• Insert intra-aortic balloon pump immediately for stabilization before surgery 2

In-Hospital Pharmacotherapy

All STEMI patients require the following medications unless contraindicated:

• Dual antiplatelet therapy (DAPT): Continue aspirin 75-100 mg daily plus ticagrelor 90 mg twice daily or prasugrel 10 mg daily for 12 months 1
• High-intensity statin: Initiate immediately with target LDL-C <70 mg/dL (1.8 mmol/L) or ≥50% reduction 1
• Beta-blockers: Start orally in patients with heart failure and/or LVEF <40% unless contraindicated 1
• ACE inhibitors: Initiate within 24 hours in patients with heart failure, LV systolic dysfunction, diabetes, or anterior infarction 1
• Proton pump inhibitor: Add to DAPT in patients at high risk of gastrointestinal bleeding 1

Diagnostic Evaluation

• Perform routine echocardiography during hospitalization to assess LV and RV function, detect mechanical complications, and exclude LV thrombus 1

Critical Pitfalls to Avoid

• Never delay primary PCI to obtain additional imaging or consultations—time is myocardium 2, 1
• Do not administer nitrates to patients who have taken phosphodiesterase-5 inhibitors (sildenafil, tadalafil) within 24-48 hours due to risk of severe hypotension 3
• Avoid fondaparinux for primary PCI (use only with fibrinolysis) 1
• Do not withhold reperfusion therapy based on age alone—elderly patients derive similar relative benefit 2
• Recognize that women, elderly, and diabetic patients often present with atypical symptoms, leading to delayed diagnosis 1

Post-Discharge Management

• Continue aspirin indefinitely and P2Y12 inhibitor for 12 months 1
• Enroll all patients in cardiac rehabilitation programs 1
• Provide smoking cessation counseling with pharmacological support 1
• Assess non-infarct related artery lesions before hospital discharge in stable patients 1