What is the management for a patient presenting with chest pain, electrocardiogram (ECG) ST elevation, and elevated creatine kinase-mb (CKMB) indicating myocardial infarction?

Management of ST-Elevation Myocardial Infarction (STEMI)

This patient requires immediate primary percutaneous coronary intervention (PCI) as the definitive reperfusion strategy, with direct transfer to the catheterization laboratory bypassing the emergency department, to be performed within 90-120 minutes of first medical contact. 1

Immediate Reperfusion Strategy

Primary PCI is the gold standard reperfusion therapy and must be initiated urgently. The patient should be transferred directly to the catheterization laboratory, bypassing the emergency department and CCU/ICCU, for immediate coronary angiography with PCI of the culprit artery. 1 This recommendation carries Class I, Level A evidence for all STEMI patients with symptoms less than 12 hours duration. 1

If primary PCI cannot be performed within 120 minutes of STEMI diagnosis, fibrinolytic therapy should be initiated immediately using a fibrin-specific agent (tenecteplase, alteplase, or reteplase), preferably in the pre-hospital setting. 1 However, given the elevated CKMB of 450 indicating established myocardial necrosis, every effort should be made to achieve primary PCI as the preferred strategy, as the benefit of reperfusion is highly time-dependent with greatest mortality benefit within the first 3 hours. 2

Antithrombotic Regimen

Antiplatelet Therapy

Aspirin 150-325 mg oral or IV (if unable to swallow) should be administered immediately if not already given. 1, 3 This carries Class I, Level B recommendation. 1

A potent P2Y12 inhibitor must be given before or at the time of PCI and maintained for 12 months. 1 Specifically:

• Prasugrel or ticagrelor are preferred over clopidogrel (Class I, Level A). 1
• Prasugrel: 60 mg loading dose, then 10 mg daily. 4
• If clopidogrel is used (when prasugrel/ticagrelor unavailable or contraindicated): 600 mg loading dose. 1

Critical prasugrel considerations:

• Contraindicated in patients with prior TIA or stroke. 4
• Generally not recommended in patients ≥75 years except in high-risk situations (diabetes or prior MI). 4
• Consider 5 mg daily maintenance dose if body weight <60 kg due to increased bleeding risk. 4
• Discontinue at least 7 days prior to any surgery when possible. 4

Anticoagulation

For primary PCI: Unfractionated heparin as weight-adjusted IV bolus followed by infusion. 1, 3 Fondaparinux is not recommended for primary PCI (Class III, Level B). 1

For fibrinolytic therapy (if PCI unavailable): Enoxaparin IV followed by subcutaneous is preferred over unfractionated heparin (Class I, Level A), continued until revascularization or for duration of hospital stay up to 8 days. 1

Symptom Management

Morphine 4-8 mg IV with additional 2 mg doses at 5-15 minute intervals should be administered for pain control and anxiety reduction. 3 Morphine also reduces sympathetic drive and myocardial oxygen demand. 2

Routine oxygen is not recommended unless SaO2 is <90% (Class III, Level B). 1

Avoid nitrates if there is any history of phosphodiesterase-5 inhibitor use (such as tadalafil within 48 hours), as this combination can cause severe, potentially fatal hypotension. 2

Post-Reperfusion Management

If Fibrinolysis is Performed

All patients receiving fibrinolysis must be transferred to a PCI-capable center immediately after fibrinolysis. 1 The following interventions are then indicated:

• Emergency angiography and PCI immediately if heart failure/shock develops (Class I, Level A). 1
• Rescue PCI immediately if fibrinolysis fails (<50% ST-segment resolution at 60-90 minutes) or with hemodynamic/electrical instability (Class I, Level A). 1
• Angiography and PCI of the infarct-related artery between 2-24 hours after successful fibrinolysis (Class I, Level A). 1, 2

Monitoring and Assessment

Routine echocardiography during hospital stay is recommended to assess LV and RV function, detect early post-MI mechanical complications, and exclude LV thrombus (Class I, Level B). 1, 2

Monitor the patient for at least 24 hours after reperfusion therapy with continuous ECG monitoring and defibrillator capacity. 1

Long-Term Antithrombotic Strategy

Dual antiplatelet therapy (DAPT) with aspirin 75-100 mg plus ticagrelor or prasugrel (or clopidogrel if unavailable/contraindicated) should be continued for 12 months unless excessive bleeding risk exists (Class I, Level A). 1

A proton pump inhibitor (PPI) in combination with DAPT is recommended for patients at high risk of gastrointestinal bleeding (Class I, Level B). 1

Critical Pitfalls to Avoid

Do not delay reperfusion therapy waiting for cardiac biomarkers - treatment should be initiated based on clinical presentation and ECG findings alone. 3 The elevated CKMB of 450 confirms the diagnosis but should not have delayed treatment initiation. 5, 6, 7

Do not give NSAIDs for pain relief due to prothrombotic effects in STEMI patients. 3

Suspect bleeding in any patient who becomes hypotensive after coronary angiography, PCI, or other procedures while on prasugrel. 4 If possible, manage bleeding without discontinuing prasugrel, as premature discontinuation increases risk of stent thrombosis, MI, and death. 4

Do not start prasugrel in patients likely to undergo urgent CABG, as bleeding risk is substantial. 4