What is the management strategy for acute ST-Elevation Myocardial Infarction (STEMI) within the golden hour?

Acute STEMI Management Within the Golden Hour

The absolute priority in acute STEMI is achieving reperfusion within 90 minutes of first medical contact via primary PCI, or initiating fibrinolytic therapy within 30 minutes if PCI cannot be performed within 120 minutes of diagnosis. 1, 2

Immediate Actions at First Medical Contact

Diagnosis (Target: Within 10 Minutes)

• Obtain and interpret 12-lead ECG within 10 minutes of first medical contact 1, 2
• Initiate continuous ECG monitoring with defibrillator capacity immediately 1
• Do not administer routine oxygen unless oxygen saturation is <90% 1

Initial Pharmacotherapy (Administer Immediately)

Aspirin:

• Administer 162-325 mg non-enteric coated aspirin to be chewed immediately 1
• Use IV aspirin (150-325 mg) only if patient cannot swallow 1, 2
• Non-enteric formulations provide more rapid buccal absorption than enteric-coated preparations 1

Morphine for Pain Relief:

• Give 2-4 mg IV with increments of 2-8 mg repeated at 5-15 minute intervals as needed 1

Beta-Blockers:

• Administer oral beta-blocker promptly to all patients without contraindications 1
• IV beta-blockers are reasonable if tachyarrhythmia or hypertension is present 1

Reperfusion Strategy Selection

Primary PCI (Preferred Strategy)

Primary PCI is the preferred reperfusion method when performed by an experienced team (>75 cases/year per operator, >36 cases/year per center) within 90-120 minutes of STEMI diagnosis. 1, 2, 3

Pre-PCI Antiplatelet Therapy:

• Administer a potent P2Y12 inhibitor before or at the time of PCI: prasugrel or ticagrelor preferred, clopidogrel if these are unavailable or contraindicated 1, 2
• For prasugrel: 60 mg loading dose, then 10 mg daily (reduce to 5 mg daily if weight <60 kg) 4
• Prasugrel is generally not recommended in patients ≥75 years due to increased bleeding risk 4

Anticoagulation During PCI:

• Unfractionated heparin IV bolus at 100 U/kg (60 U/kg if GPIIb/IIIa inhibitors used) 1, 2
• Fondaparinux is contraindicated for primary PCI 1

Logistics:

• Transfer patients directly to catheterization laboratory, bypassing emergency department 1, 2
• PCI-capable centers must provide 24/7 service without delay 1, 2

Fibrinolytic Therapy (When PCI Not Available Within Time Window)

Initiate fibrinolytic therapy within 30 minutes of first medical contact if primary PCI cannot be performed within 90-120 minutes of diagnosis. 1, 3

Fibrinolytic Agent Selection:

• Use a fibrin-specific agent: tenecteplase, alteplase, or reteplase 1, 5, 2
• Tenecteplase is administered as single weight-adjusted IV bolus: 30 mg (<60 kg), 35 mg (60-69 kg), 40 mg (70-79 kg), 45 mg (80-89 kg), 50 mg (≥90 kg) 5
• Reduce tenecteplase dose by 50% in patients ≥75 years to reduce stroke risk 5

Adjunctive Therapy with Fibrinolysis:

• Aspirin 162-325 mg orally or IV 1, 5, 2
• Clopidogrel in addition to aspirin 1, 5, 2
• Anticoagulation until revascularization or up to 8 days: enoxaparin IV followed by subcutaneous (preferred) or unfractionated heparin as weight-adjusted IV bolus followed by infusion 1, 5, 2

Post-Fibrinolytic Management:

• Transfer all patients to PCI-capable center immediately after fibrinolysis 1, 5, 2
• Perform rescue PCI immediately if fibrinolysis fails (<50% ST-segment resolution at 60-90 minutes) or if hemodynamic/electrical instability occurs 1, 5, 2
• Perform angiography and PCI of infarct-related artery between 2-24 hours after successful fibrinolysis 1, 5, 2

Special Circumstances Requiring Immediate Action

Cardiogenic Shock

• Transport immediately to facility capable of cardiac catheterization and rapid revascularization (PCI and CABG) 1, 2
• Emergency angiography and PCI indicated regardless of time from symptom onset 1, 2

Cardiac Arrest with STEMI

• Primary PCI strategy is recommended in patients with resuscitated cardiac arrest and ECG consistent with STEMI 1, 2
• Initiate targeted temperature management early after resuscitation in patients who remain unresponsive 1

Contraindications to Fibrinolysis

• Immediately transport to PCI-capable facility or transfer within 30 minutes 1
• Absolute contraindications include: prior intracranial hemorrhage, active bleeding, ischemic stroke within 3 months, suspected aortic dissection 1, 6

Critical Time-Dependent Mortality Benefit

The greatest mortality benefit occurs within the first hour of symptom onset, with 35 lives saved per 1000 patients when reperfusion is achieved within the first hour, compared to only 16 lives saved per 1000 when given 7-12 hours after symptom onset. 3

Common Pitfalls to Avoid

• Do not delay reperfusion to administer facilitated PCI strategies (full-dose fibrinolysis followed by immediate PCI)—this approach may be harmful 1
• Do not use streptokinase for repeat fibrinolysis if previously administered within 5 days 1
• Do not perform routine thrombus aspiration or deferred stenting—these are contraindicated 2
• Do not use fondaparinux for primary PCI 1
• Avoid intramuscular injections and nonessential handling after fibrinolytic administration to minimize bleeding 6
• Recognize atypical presentations, especially in women, elderly, and diabetic patients, which may lead to delayed diagnosis 2