What is the initial management for a patient presenting with Acute Coronary Syndrome (ACS) ST-Elevation Myocardial Infarction (STEMI)?

Initial Management of STEMI

For patients presenting with STEMI, immediately initiate primary percutaneous coronary intervention (PCI) within 120 minutes of diagnosis as the preferred reperfusion strategy, supported by dual antiplatelet therapy with aspirin plus a potent P2Y12 inhibitor (prasugrel or ticagrelor), and transfer the patient directly to the catheterization laboratory bypassing the emergency department. 1, 2

Immediate Diagnostic Steps

Obtain a 12-lead ECG within 10 minutes of first medical contact to confirm STEMI diagnosis (persistent ST-segment elevation or new left bundle branch block). 1, 2

• Initiate continuous ECG monitoring with defibrillator capacity immediately upon suspicion of STEMI. 1, 2
• Do NOT administer routine oxygen therapy unless oxygen saturation is <90%. 1, 2

Reperfusion Strategy Selection

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

Primary PCI Strategy (Preferred)

If primary PCI can be performed within 120 minutes of diagnosis:

• Transfer patient directly to catheterization laboratory, bypassing emergency department and ICU. 1, 2
• PCI-capable centers must provide 24/7 service without delay. 1, 2
• Use radial artery access and drug-eluting stents as standard of care. 2

Fibrinolytic Strategy (When PCI Delayed)

If primary PCI cannot be performed within 120 minutes AND patient presents within 12 hours of symptom onset:

• Administer fibrinolytic therapy immediately, preferably in pre-hospital setting. 1, 2, 3
• Use fibrin-specific agents: tenecteplase (preferred single bolus), alteplase, or reteplase. 2, 3
• For patients ≥75 years old, reduce tenecteplase dose by 50% to minimize stroke risk. 2, 3
• Transfer ALL patients to PCI-capable center immediately after fibrinolysis. 3
• Assess reperfusion success at 60-90 minutes by measuring ST-segment resolution; if <50% resolution occurs, perform immediate rescue PCI. 3

Antiplatelet Therapy

Administer aspirin 150-325 mg orally (or 250-500 mg IV if unable to swallow) as soon as possible. 1, 2

For patients undergoing primary PCI:

• Ticagrelor (180 mg loading dose, then 90 mg twice daily) is the preferred P2Y12 inhibitor for most patients at moderate-to-high ischemic risk. 1, 4
• Prasugrel (60 mg loading dose, then 10 mg daily) is recommended for patients proceeding to PCI without contraindications. 1
  • Do NOT use prasugrel in patients with prior stroke/TIA, age >75 years, or weight <60 kg. 4
  • Do NOT administer prasugrel before coronary anatomy is known. 1
• Clopidogrel (300-600 mg loading dose, then 75 mg daily) only if ticagrelor or prasugrel are unavailable or contraindicated. 1
  • Consider alternative P2Y12 inhibitor in CYP2C19 poor metabolizers, as clopidogrel has reduced effectiveness in these patients. 5

For patients receiving fibrinolysis:

• Administer clopidogrel with aspirin (ticagrelor and prasugrel are not validated for fibrinolytic strategy). 2, 3

Anticoagulation

For primary PCI:

• Administer unfractionated heparin (UFH) as IV bolus at 100 U/kg (or 60 U/kg if GPIIb/IIIa inhibitors used). 2
• Do NOT use fondaparinux for primary PCI. 2

For fibrinolysis:

• Use enoxaparin or unfractionated heparin until revascularization or for duration of hospital stay (up to 8 days). 2, 3

Special Populations Requiring Immediate Intervention

Perform emergency angiography and PCI immediately in patients with:

• Cardiogenic shock or hemodynamic instability 2
• Resuscitated cardiac arrest with ECG showing STEMI 1, 2
• Mechanical complications of MI 1
• Life-threatening arrhythmias 1

For cardiac arrest survivors who remain unresponsive, initiate targeted temperature management early. 1

Critical Pitfalls to Avoid

• Do NOT routinely perform thrombus aspiration or deferred stenting during primary PCI—these are contraindicated. 2
• Do NOT combine fibrinolysis with planned immediate PCI—this increases mortality. 3
• Do NOT perform routine PCI of occluded infarct-related artery >48 hours after symptom onset in asymptomatic patients. 1, 3
• Avoid concomitant use of clopidogrel with omeprazole or esomeprazole, as these significantly reduce clopidogrel's antiplatelet activity. 5
• Watch for atypical presentations, especially in women, elderly, and diabetic patients, which may lead to delayed diagnosis. 2

In-Hospital Management Essentials

• Continue dual antiplatelet therapy (aspirin plus P2Y12 inhibitor) for 12 months unless contraindications exist. 1, 2
• Initiate high-intensity statin therapy as early as possible. 1, 2
• Start beta-blockers orally in patients with heart failure and/or LVEF <40%. 2
• Initiate ACE inhibitors within 24 hours in patients with heart failure, LV dysfunction, diabetes, or anterior infarct. 2
• Perform routine echocardiography to assess ventricular function, detect mechanical complications, and exclude LV thrombus. 2