What is the recommended acute management for a patient presenting with ST‑segment elevation myocardial infarction?

Acute Management of ST-Elevation Myocardial Infarction (STEMI)

Immediate primary percutaneous coronary intervention (PCI) within 120 minutes of diagnosis is the preferred reperfusion strategy, with aspirin and a potent P2Y12 inhibitor (prasugrel or ticagrelor) administered immediately; if this time window cannot be met, initiate fibrinolytic therapy within 10 minutes of diagnosis. 1, 2

Immediate Assessment and First Actions

Obtain and interpret a 12-lead ECG within 10 minutes of first medical contact to confirm STEMI, and begin continuous ECG monitoring with defibrillator capability immediately. 1, 2, 3

Administer aspirin 150–325 mg (chewable or IV if unable to swallow) as soon as possible without delay. 1, 2, 3

Give oxygen only when SpO₂ < 90%—routine supplemental oxygen is not recommended and may be harmful. 1, 2, 3

Provide opioid analgesia (morphine) as needed for pain relief. 2

Reperfusion Strategy Selection: The Critical Decision

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

Primary PCI (Preferred Strategy)

Primary PCI is indicated when it can be performed within 120 minutes of STEMI diagnosis by an experienced team at a PCI-capable center. 1, 2, 3

Time targets:

• Door-to-balloon ≤ 90 minutes for patients presenting directly to a PCI-capable center 2
• First-medical-contact-to-balloon ≤ 120 minutes for patients requiring inter-facility transfer 2

Patients must bypass the emergency department and proceed directly to the catheterization laboratory to minimize door-to-balloon time. 1, 2

Antithrombotic regimen for primary PCI:

• Aspirin 150–325 mg loading dose (already given) 1, 2
• Prasugrel 60 mg loading dose (preferred P2Y12 inhibitor) followed by 10 mg daily for 12 months 1, 2, 3
• Ticagrelor 180 mg loading dose (alternative to prasugrel) followed by 90 mg twice daily for 12 months 1, 2, 3
• Clopidogrel 300–600 mg loading dose only if prasugrel and ticagrelor are unavailable or contraindicated, then 75 mg daily 1, 2
• Unfractionated heparin as first-line anticoagulant (enoxaparin or bivalirudin are alternatives) 1, 2, 3

Fibrinolytic Therapy (When PCI Cannot Meet Time Targets)

Fibrinolytic therapy is indicated when primary PCI cannot be performed within 120 minutes of STEMI diagnosis and the patient presents within 12 hours of symptom onset without contraindications. 1, 2, 4, 3

Target door-to-needle ≤ 30 minutes—ideally within 10 minutes of diagnosis. 2, 4, 3

Pre-hospital administration by trained paramedics is the most effective way to shorten delays when PCI is not rapidly accessible. 2

Fibrinolytic agent selection: Use a fibrin-specific agent: tenecteplase, alteplase, or reteplase. 2, 4, 3, 5

Antithrombotic regimen for fibrinolysis:

• Aspirin 150–325 mg loading dose (already given) 2, 4, 3
• Clopidogrel 300–600 mg loading dose immediately—this is the only P2Y12 inhibitor indicated with fibrinolysis (do not use prasugrel or ticagrelor initially) 1, 4, 3
• Enoxaparin (preferred): IV bolus followed by subcutaneous administration (preferred over unfractionated heparin) 1, 4

Post-fibrinolysis management:

• Transfer all patients to a PCI-capable center immediately after fibrinolysis 4, 3
• Perform routine angiography between 2–24 hours after successful fibrinolysis 4, 3
• Switch from clopidogrel to prasugrel or ticagrelor at the time of PCI, and maintain for 12 months 4, 3

Post-Reperfusion Monitoring

Monitor ST-segment resolution, cardiac rhythm, and symptoms for 60–180 minutes after reperfusion. 2

Successful reperfusion is suggested by symptom relief, hemodynamic/electrical stability, and ≥50% reduction in ST-segment elevation on a follow-up ECG at 60–90 minutes. 2

Continue telemetry monitoring for at least 24 hours to detect life-threatening arrhythmias, especially in patients with heart failure, shock, or serious arrhythmias. 1, 2, 3

Special Circumstances

Cardiogenic Shock

Emergency revascularization (PCI or CABG) is indicated for patients < 75 years with shock developing ≤ 36 hours after STEMI and severe multivessel or left-main disease, performed within 18 hours of shock onset. 2

Selected patients ≥ 75 years with good prior functional status may also benefit. 2

Resuscitated Cardiac Arrest

Primary PCI is the preferred strategy when the post-arrest ECG shows STEMI. 1, 2, 3

Targeted temperature management should be initiated early in unresponsive patients. 1, 2, 3

Avoid pre-hospital rapid infusion of large volumes of cold IV fluid for cooling after return of spontaneous circulation. 1, 2

Routine PCI of Occluded Infarct-Related Artery

Do not perform routine PCI of an occluded infarct-related artery > 48 hours after symptom onset in asymptomatic patients—this is contraindicated. 1, 3

Critical Pitfalls to Avoid

Never delay reperfusion for additional diagnostics or consultations—time to reperfusion is the single most critical determinant of outcome. 2

Do not use prasugrel or ticagrelor as the initial P2Y12 inhibitor with fibrinolytic therapy—clopidogrel is specifically indicated in this setting, with transition to potent agents at the time of PCI. 4, 3

Do not delay transfer to a PCI-capable center after fibrinolysis—all patients require angiography regardless of apparent lysis success. 4, 3

Do not miss the 2–24 hour window for routine angiography after successful fibrinolysis—this timing is evidence-based and improves outcomes. 4, 3

Do not withhold aspirin or P2Y12 inhibitors due to bleeding concerns in most acute STEMI scenarios—mortality benefit outweighs bleeding risk. 2