What is the management approach for a patient presenting with ST-elevation myocardial infarction (STEMI)?

STEMI Management

Immediate Reperfusion Strategy

Primary PCI is the preferred reperfusion strategy and must be performed within 120 minutes of STEMI diagnosis (first medical contact-to-device time); if this cannot be achieved, administer fibrinolytic therapy within 10-30 minutes of diagnosis. 1, 2

Time-Based Decision Algorithm

• If primary PCI achievable within 120 minutes: Proceed directly to primary PCI as the definitive reperfusion strategy 1, 3
• If primary PCI NOT achievable within 120 minutes: Administer fibrinolytic therapy immediately (within 10 minutes of STEMI diagnosis per ESC, or within 30 minutes of hospital arrival per ACC/AHA) 1, 2
• Systems goal for PCI-capable hospitals: First medical contact-to-balloon time <90-120 minutes 1, 2

The 2017 ESC guidelines updated the time window from 90 to 120 minutes, recognizing real-world logistics while maintaining emphasis on minimizing total ischemic time. 1

Pre-Hospital System Optimization

• Emergency Medical Services (EMS) should perform pre-hospital ECG diagnosis and directly transport patients to the cardiac catheterization laboratory, bypassing the emergency department entirely 1, 3
• Pre-hospital diagnosis and direct catheterization laboratory admission reduces door-to-balloon time by approximately 27-47 minutes and achieves the 90-minute target in 94% of cases versus only 29% with traditional emergency room routing 4, 5
• EMS must immediately alert the PCI center after STEMI diagnosis to enable catheterization laboratory activation during transport 1

Immediate Pharmacotherapy

Antiplatelet Therapy

Administer aspirin 162-325 mg (non-enteric coated, chewable preferred) immediately upon first medical contact, followed by 75-100 mg daily indefinitely. 2, 3, 6

• For primary PCI: Add a potent P2Y12 inhibitor (ticagrelor 180 mg loading dose OR prasugrel 60 mg loading dose) before or at the time of PCI 1, 2, 6
• For fibrinolysis: Add clopidogrel 300 mg loading dose (clopidogrel is reserved specifically for fibrinolysis patients, NOT for primary PCI) 1, 6
• Ticagrelor and prasugrel are superior to clopidogrel for primary PCI and represent Class I recommendations 1, 6

Administer the P2Y12 inhibitor loading dose as early as possible—ideally in the ambulance or emergency department before catheterization—to maximize platelet inhibition at the time of PCI. 6, 7

Anticoagulation

Administer unfractionated heparin (UFH) as the preferred anticoagulant for primary PCI, with weight-based dosing to achieve target ACT of 250-350 seconds. 1, 6

• UFH dosing: 70-100 units/kg IV bolus (60 units/kg if using GP IIb/IIIa inhibitors) 6
• Alternative anticoagulants: Enoxaparin or bivalirudin may be used, but avoid switching between agents during the acute phase as this increases bleeding risk 1, 6
• Critical pitfall: Never use fondaparinux alone during PCI—it increases catheter thrombosis risk and requires additional UFH 6
• Continue heparin through PCI and discontinue after procedure once hemostasis is achieved 6

Technical Aspects of Primary PCI

Routine radial artery access and drug-eluting stent (DES) implantation are the standard of care for primary PCI. 1

• Routine thrombus aspiration is contraindicated (no benefit, potential harm) 1
• Routine deferred stenting is contraindicated 1
• Target ACT during PCI: 250-300 seconds (HemoTec) or 300-350 seconds (Hemochron) when no GP IIb/IIIa inhibitor is planned 6

Management of Multivessel Disease

• Treat severe stenosis in non-infarct-related arteries (non-IRA) before hospital discharge, either immediately during index PCI or staged at a later time 1
• In cardiogenic shock, perform non-IRA PCI during the index procedure 1

Special Populations and Complications

Cardiogenic Shock

Perform emergency revascularization (PCI or CABG) immediately in cardiogenic shock patients, regardless of time delay from MI onset. 2, 3

• Consider intra-aortic balloon counterpulsation for patients not quickly stabilized with pharmacological therapy 3, 8

Post-Cardiac Arrest

Patients with ST-elevation on post-resuscitation ECG should undergo primary PCI strategy immediately. 1, 2

• For post-arrest patients without ST-elevation but high suspicion of ongoing ischemia, perform urgent angiography within 2 hours after excluding non-coronary causes 1
• The decision for urgent angiography must account for factors associated with poor neurological outcome 1

Emergency CABG Indications (Class I)

• Failed PCI with persistent pain or hemodynamic instability in patients with suitable coronary anatomy 2
• Persistent or recurrent ischemia refractory to medical therapy with significant myocardium at risk 2
• Mechanical complications requiring surgical repair (ventricular septal rupture, papillary muscle rupture with severe mitral regurgitation) 2

Fibrinolysis-Specific Considerations

When fibrinolysis is chosen, use tenecteplase (TNKase) or alteplase with weight-based dosing, administered within 10-30 minutes of STEMI diagnosis. 1, 2, 9

Fibrinolytic Contraindications (Absolute)

• Active internal bleeding 9
• History of cerebrovascular accident 9
• Intracranial or intraspinal surgery/trauma within 2 months 9
• Intracranial neoplasm, arteriovenous malformation, or aneurysm 9
• Known bleeding diathesis 9
• Severe uncontrolled hypertension 9

Post-Fibrinolysis Management

Do NOT perform immediate PCI after successful fibrinolysis—this strategy increases bleeding, recurrent ischemia, and death without benefit. 2, 9

• Rescue PCI should be performed for failed fibrinolysis (persistent chest pain, <50% ST-segment resolution at 60-90 minutes) 2
• Routine PCI after successful fibrinolysis should be performed 3-24 hours later as part of an early invasive strategy, NOT immediately 2, 10
• The FDA label for tenecteplase specifically warns against combining fibrinolysis with planned immediate PCI due to increased mortality (6.7% vs 4.9%), cardiogenic shock (6.3% vs 4.8%), heart failure (12% vs 9.2%), and recurrent MI (6.1% vs 3.7%) 9

Fibrinolysis Monitoring

• Monitor for reperfusion arrhythmias (sinus bradycardia, accelerated idioventricular rhythm, ventricular tachycardia) and have anti-arrhythmic therapy immediately available 9
• Avoid intramuscular injections and minimize arterial punctures for the first few hours after fibrinolysis 9
• If arterial puncture necessary, use upper extremity vessel accessible to manual compression and apply pressure for at least 30 minutes 9

Post-STEMI Medical Management

Beta-Blockers

Initiate oral beta-blockers within 24 hours in patients who are NOT at high risk for complications (no signs of heart failure, hemodynamic instability, or cardiogenic shock). 1, 3

• Continue beta-blockers indefinitely in all eligible patients 3
• The 2007 ACC/AHA focused update downgraded early beta-blocker administration from routine to selective based on COMMIT trial findings showing potential harm in high-risk patients 1

ACE Inhibitors/ARBs

Initiate ACE inhibitors within 24 hours in all patients, particularly those with anterior MI, heart failure, or ejection fraction ≤40%. 3

• Use ARBs if ACE inhibitor intolerant 3

High-Intensity Statin Therapy

Initiate high-intensity statin therapy immediately with target LDL-C <70 mg/dL or ≥50% reduction from baseline. 2

Dual Antiplatelet Therapy (DAPT) Duration

Continue DAPT (aspirin plus ticagrelor 90 mg twice daily OR prasugrel 10 mg daily) for 12 months after PCI unless contraindications develop. 1, 2

• After 12 months, continue aspirin 75-100 mg daily indefinitely 1

Diagnostic Considerations

ECG Diagnosis

• STEMI is defined as ST-segment elevation ≥0.1 mV (1 mm) in at least two contiguous precordial or adjacent limb leads 2, 3
• STEMI equivalents requiring immediate reperfusion strategy: New or presumed new left bundle branch block, ventricular pacing, hyperacute T-waves, isolated ST-depression in anterior leads (posterior MI), or diffuse ST-depression with ST-elevation in aVR 1, 2
• Obtain 12-lead ECG within 10 minutes of emergency department arrival 3
• If initial ECG non-diagnostic but clinical suspicion high, perform serial ECGs at 5-10 minute intervals 3

Post-Reperfusion Assessment

• Perform routine echocardiography during hospital stay to assess LV/RV function, detect mechanical complications, and exclude LV thrombus 3
• Obtain follow-up ECGs at 24 hours and hospital discharge to assess reperfusion success and infarct extent 3

Critical Pitfalls to Avoid

• Never combine fibrinolysis with immediate planned PCI—choose one primary reperfusion strategy 2, 9
• Never use clopidogrel instead of ticagrelor/prasugrel for primary PCI—clopidogrel is reserved for fibrinolysis patients only 1, 6
• Never switch between anticoagulants (enoxaparin ↔ UFH) during acute phase—increases bleeding risk 6
• Never use fondaparinux alone during PCI—requires additional UFH to prevent catheter thrombosis 6
• Never delay reperfusion for "stabilization"—time is myocardium 1, 3
• Never route patients through the emergency department if direct catheterization laboratory access is available—this adds 27-47 minutes to door-to-balloon time 4, 5