What are the guidelines for managing ST-Elevation Myocardial Infarction (STEMI)?

Management of ST-Elevation Myocardial Infarction (STEMI)

Primary percutaneous coronary intervention (PCI) should be performed within 90 minutes of first medical contact for all STEMI patients when available, or fibrinolytic therapy should be administered within 30 minutes if PCI cannot be performed within 120 minutes. 1, 2

Initial Assessment and Management

• Immediately administer 162-325 mg of non-enteric coated aspirin to all STEMI patients upon first medical contact 1
• A 12-lead ECG should be performed and shown to an experienced emergency physician within 10 minutes of emergency department arrival for all patients with chest discomfort or symptoms suggestive of STEMI 3
• If the initial ECG is not diagnostic but clinical suspicion remains high, serial ECGs at 5-10 minute intervals or continuous 12-lead ST-segment monitoring should be performed 3
• In patients with inferior STEMI, right-sided ECG leads should be obtained to screen for right ventricular infarction 3
• Administer supplemental oxygen only to patients with arterial oxygen desaturation (SaO₂ <90%) or respiratory distress 1, 2
• Provide morphine sulfate for patients with ongoing ischemic pain or pulmonary congestion 1, 2
• Initiate oral beta-blocker therapy promptly in patients without contraindications (heart failure, hypotension, bradycardia) 1, 2

Reperfusion Strategy Decision-Making

• Every community should have a written protocol guiding EMS personnel in determining where to take STEMI patients 3
• The critical decision point is whether primary PCI can be performed within 120 minutes of first medical contact 3, 2
• For patients presenting within 12 hours of symptom onset without contraindications, immediate reperfusion therapy is indicated 3
• For high-risk patients (anterior MI, age <75 years) presenting within 2 hours of symptom onset, the PCI-related delay should not exceed 90 minutes 3

Primary PCI Strategy

• Patients should be brought directly to the catheterization laboratory, bypassing the emergency room when possible 4
• Administer dual antiplatelet therapy before PCI, including aspirin and a P2Y12 inhibitor (prasugrel, ticagrelor, or clopidogrel) as early as possible 1, 2
• Anticoagulation with unfractionated heparin or bivalirudin should be initiated 4
• Manual thrombus aspiration may be considered for patients with high thrombus burden 4
• For patients receiving stents, dual antiplatelet therapy should be continued for at least 12 months 2

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
• After fibrinolysis, transfer patients to a PCI-capable facility for coronary angiography within 24 hours (but not before 3 hours) 4
• Clopidogrel should be used as the P2Y12 inhibitor of choice when fibrinolytic therapy is administered 4

Special Populations

• Patients with cardiogenic shock and age <75 years should be immediately transferred to facilities capable of cardiac catheterization and rapid revascularization if it can be performed within 18 hours of shock onset 3
• For patients ≥75 years with cardiogenic shock, emergency revascularization should still be considered, especially in those with good prior functional status 2
• Patients with STEMI who have contraindications to fibrinolytic therapy should be transferred promptly (door-to-departure time <30 minutes) to PCI-capable facilities 3

Post-STEMI Care

• Initiate ACE inhibitors within 24 hours in patients with anterior STEMI, heart failure, or ejection fraction ≤0.40 1, 2
• Start high-intensity statin therapy in all STEMI patients without contraindications 1
• Continue dual antiplatelet therapy with aspirin and a P2Y12 inhibitor for at least 12 months in patients receiving stents 2
• Patients who routinely took nonsteroidal anti-inflammatory drugs (except aspirin) before STEMI should discontinue these agents due to increased risks of adverse outcomes 3

Management of Complications

• For cardiogenic shock, emergency revascularization is recommended regardless of time delay from MI onset 1, 2
• Intra-aortic balloon counterpulsation is useful for patients with cardiogenic shock not quickly stabilized with pharmacological therapy 2
• Ventricular septal rupture, free wall rupture, and papillary muscle rupture require urgent surgical consultation 2

Common Pitfalls and Caveats

• Do not delay reperfusion therapy to wait for cardiac biomarker results; initiate treatment based on clinical presentation and ECG findings 3
• Avoid immediate-release nifedipine in STEMI patients 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
• Serial biomarker measurements should not be relied on to diagnose reinfarction within the first 18 hours after STEMI onset 3