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

STEMI Management

Immediately obtain a 12-lead ECG within 10 minutes of first medical contact, initiate continuous cardiac monitoring with defibrillator capacity, and choose primary PCI if it can be performed within 120 minutes of diagnosis—otherwise administer fibrinolytic therapy within 10 minutes combined with aspirin, clopidogrel, and anticoagulation. 1, 2

Initial Diagnosis and Stabilization

ECG and Monitoring:

• Record and interpret a 12-lead ECG at the point of first medical contact with a maximum 10-minute delay 1
• Begin ECG monitoring with defibrillator capacity immediately upon patient contact 1
• Look for ST-segment elevation in two contiguous leads, but also recognize STEMI equivalents including new bundle branch block, ventricular pacing, hyperacute T-waves, isolated ST-depression in anterior leads, or universal ST depression with ST-elevation in aVR 2

Oxygen Therapy:

• Administer oxygen only if oxygen saturation is below 90%—routine oxygen administration is contraindicated in patients with adequate saturation 1, 2

Reperfusion Strategy Decision

The critical decision point is whether primary PCI can be performed within 120 minutes of STEMI diagnosis: 1, 2, 3

Primary PCI Pathway (Preferred if ≤120 minutes)

Immediate Pharmacotherapy:

• Aspirin loading dose (oral or IV if unable to swallow) 1, 2
• Prasugrel or ticagrelor loading dose (not clopidogrel)—these potent P2Y12 inhibitors are specifically indicated for primary PCI 1, 2
• Unfractionated heparin as first-line anticoagulant (enoxaparin or bivalirudin are alternatives) 1, 2

Procedural Approach:

• Use radial access as the standard approach 2
• Implant drug-eluting stents routinely 2
• Do not perform routine thrombus aspiration or deferred stenting—these strategies are contraindicated 2
• Transfer patients directly to the catheterization laboratory, bypassing the emergency department 1

Fibrinolysis Pathway (If PCI Cannot Be Performed Within 120 Minutes)

This pathway applies to patients presenting within 12 hours of symptom onset without contraindications: 1, 4

Immediate Pharmacotherapy:

• Initiate fibrinolytic therapy within 10 minutes of STEMI diagnosis, preferably in the pre-hospital setting 2, 4
• Use a fibrin-specific agent: tenecteplase, alteplase, or reteplase 1, 4
• Aspirin loading dose (oral or IV) 1, 4
• Clopidogrel loading dose—this is the only P2Y12 inhibitor indicated with fibrinolysis (do not use prasugrel or ticagrelor initially) 1, 2, 4
• Enoxaparin: IV bolus followed by subcutaneous administration (preferred over unfractionated heparin) 4

Critical Post-Fibrinolysis Management:

• Transfer all patients to a PCI-capable center immediately after fibrinolysis 2, 4
• Perform routine angiography between 2-24 hours after successful fibrinolysis 2, 4
• Switch from clopidogrel to prasugrel or ticagrelor at the time of PCI 2, 4
• Perform rescue PCI immediately if fibrinolysis has failed (<50% ST-segment resolution at 60-90 minutes) or in the presence of hemodynamic or electrical instability 5

Tenecteplase Dosing Considerations:

• For patients ≥75 years old, reduce TNK dose by 50% to minimize intracranial hemorrhage risk 5
• TNKase can cause bleeding including intracranial hemorrhage; avoid intramuscular injections and nonessential handling for the first few hours 6

Special Populations

Cardiac Arrest:

• Perform primary PCI in patients with resuscitated cardiac arrest and ST-elevation on post-resuscitation ECG 1, 2, 5
• Initiate targeted temperature management early after resuscitation in patients who remain unresponsive 1, 2
• Do not use pre-hospital cooling with rapid infusion of large volumes of cold IV fluid—this is contraindicated 1

Late Presentation (>12 hours):

• Routine PCI of an occluded infarct-related artery >48 hours after onset is not indicated in asymptomatic patients 1, 5
• Emergency angiography and PCI are indicated in patients with heart failure/shock following cardiac arrest, regardless of time from symptom onset 5

Patients on Oral Anticoagulants, Renal Insufficiency, or Elderly:

• Pay special attention to dose adjustment of pharmacological strategies in these subsets 1

Post-Reperfusion Care

Monitoring and Assessment:

• Monitor patients for at least 24 hours after reperfusion therapy 1
• Pursue early ambulation and early discharge in uncomplicated patients 1, 2
• Perform routine echocardiography during hospital stay to assess left and right ventricular function, detect mechanical complications, and exclude left ventricular thrombus 2, 4

Maintenance Antithrombotic Therapy:

• Continue dual antiplatelet therapy with aspirin plus prasugrel or ticagrelor for 12 months after PCI unless contraindications exist (such as excessive bleeding risk) 1, 2, 4

Critical Pitfalls to Avoid

Antiplatelet Agent Selection:

• Never 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 2, 4

Post-Fibrinolysis Management:

• Do not delay transfer to a PCI-capable center after fibrinolysis—all patients require angiography regardless of apparent lysis success 2, 4
• Do not miss the 2-24 hour window for routine angiography after successful fibrinolysis—this timing is evidence-based and improves outcomes 2, 4

Procedural Errors:

• Do not perform routine thrombus aspiration or deferred stenting during primary PCI—these strategies are contraindicated 2
• Do not use fondaparinux for primary PCI 4

Combination Therapy:

• In patients with large STEMI, choose either thrombolysis or PCI as the primary treatment strategy—planned combination of TNKase plus PCI shows trends toward worse outcomes including increased mortality (6.7% vs. 4.9%), cardiogenic shock (6.3% vs. 4.8%), heart failure (12% vs. 9.2%), recurrent MI (6.1% vs. 3.7%), and repeat revascularization (6.6% vs. 3.4%) compared to PCI alone 6

Vascular Access:

• Avoid internal jugular and subclavian venous punctures to minimize bleeding from noncompressible sites 6
• If arterial puncture is necessary during thrombolytic infusion, use an upper extremity vessel accessible to manual compression and apply pressure for at least 30 minutes 6