What is the appropriate management for an adult patient with potential risk factors for cardiovascular disease presenting with STEMI (ST-Elevation Myocardial Infarction)?

Management of ST-Elevation Myocardial Infarction (STEMI)

Immediate reperfusion therapy is the cornerstone of STEMI management, with primary PCI preferred when it can be performed within 120 minutes of first medical contact; otherwise, fibrinolytic therapy should be administered within 30 minutes of hospital arrival. 1

Immediate Recognition and Initial Management

First Medical Contact Actions

• Administer 162-325 mg of non-enteric coated aspirin immediately upon recognition of STEMI 1
• Obtain a 12-lead ECG within 10 minutes of emergency department arrival 1
• For inferior STEMI (ST elevation in leads II, III, aVF), obtain right-sided ECG leads (V3R-V4R) to assess for right ventricular involvement 2, 1
• If initial ECG is non-diagnostic but suspicion remains high, perform serial ECGs at 5-10 minute intervals 1

Supportive Care

• Administer supplemental oxygen only if arterial oxygen desaturation (SpO2 <90%) or respiratory distress is present 3, 1
• Provide morphine sulfate 4-8 mg IV for ongoing chest pain, with additional 2 mg doses at 5-15 minute intervals as needed 3, 1
• Initiate oral beta-blocker therapy within 24 hours in patients without contraindications (avoid in frank cardiac failure, pulmonary congestion, or low-output states) 3, 1
• Start high-intensity statin therapy (atorvastatin 80 mg or rosuvastatin 40 mg) immediately 3, 1

Reperfusion Strategy Decision Algorithm

Time-Based Decision Making

The critical decision point is whether primary PCI can be performed within 120 minutes of first medical contact 1. For high-risk patients presenting within 2 hours of symptom onset, this window narrows to 90 minutes 1.

Primary PCI Strategy (Preferred)

Primary PCI is the preferred reperfusion strategy when timely access is available 1, 4, 5. This approach has become the gold standard because it achieves superior outcomes compared to fibrinolysis 4.

Pre-PCI Antiplatelet Therapy

• Administer dual antiplatelet therapy before PCI: aspirin plus a P2Y12 inhibitor (clopidogrel 75 mg daily or prasugrel 60 mg loading dose followed by 10 mg daily) 3, 1, 6
• Continue dual antiplatelet therapy for at least 12 months after stent placement 1
• For prasugrel, consider 5 mg maintenance dose in patients weighing <60 kg due to increased bleeding risk 6

Important Prasugrel Contraindications

• Do not use prasugrel in patients with prior TIA or stroke (4.2% thrombotic stroke and 2.3% intracranial hemorrhage risk) 6
• Generally avoid in patients ≥75 years unless high-risk features (diabetes, prior MI) are present 6
• Discontinue at least 7 days before planned CABG surgery 6

Fibrinolytic Strategy (When PCI Unavailable)

If primary PCI cannot be performed within 120 minutes, administer fibrinolytic therapy within 30 minutes of hospital arrival 3, 1. Streptokinase is commonly available in resource-limited settings 3.

Post-Fibrinolysis Management

• Monitor ST-segment resolution, cardiac rhythm, and symptoms for 60-180 minutes after fibrinolysis initiation 3
• Do not perform routine immediate PCI after successful fibrinolysis—this increases bleeding, recurrent ischemia, and mortality 3
• Consider rescue PCI only if fibrinolysis fails (persistent ST elevation, ongoing symptoms) 3
• Perform angiography 3-24 hours after successful fibrinolysis in high-risk patients (hemodynamic instability, LV dysfunction, elderly) 3

Special Populations and Complications

Cardiogenic Shock

• For patients <75 years with cardiogenic shock developing within 36 hours of STEMI, perform emergency revascularization within 18 hours of shock onset if severe multivessel or left main disease is present 3, 1
• Selected patients ≥75 years with good prior functional status may also benefit from emergency revascularization 3
• Consider intra-aortic balloon pump as a bridge to definitive intervention if shock does not quickly reverse with pharmacological therapy 1

Right Ventricular Infarction

• Present in up to 50% of inferior STEMIs 2
• Avoid nitrates in this setting—they can cause profound hypotension due to preload dependence 2
• Cautious volume loading may be necessary, but avoid aggressive fluid resuscitation 3

Emergency CABG Indications (Class I)

Emergency CABG should be performed in these specific circumstances 3:

• Failed PCI with persistent pain or hemodynamic instability
• Persistent refractory ischemia in patients unsuitable for PCI/fibrinolysis with significant myocardium at risk
• Mechanical complications requiring surgical repair (ventricular septal rupture, mitral valve insufficiency)
• Cardiogenic shock with severe multivessel or left main disease (as detailed above)
• Life-threatening ventricular arrhythmias with ≥50% left main stenosis or triple-vessel disease

Post-STEMI Medical Therapy

Essential Medications

• ACE inhibitors within 24 hours in patients with anterior STEMI, heart failure, or ejection fraction ≤0.40 1
• Dual antiplatelet therapy (aspirin plus P2Y12 inhibitor) for at least 12 months 1
• High-intensity statin therapy regardless of baseline cholesterol 1
• Beta-blockers within 24 hours if no contraindications 2, 1

Continuous Monitoring

• ECG monitoring for at least 24 hours to detect arrhythmias 2
• High-degree AV blocks may require temporary transvenous pacing 2

Critical Pitfalls to Avoid

Timing Errors

• Never delay reperfusion to wait for cardiac biomarker results—initiate treatment based on clinical presentation and ECG findings 1
• Do not perform routine PCI immediately after successful fibrinolysis—this strategy increases adverse events without benefit 3

Medication Errors

• Avoid immediate-release nifedipine in STEMI due to reflex sympathetic activation and hypotension 1
• Do not administer beta-blockers or calcium channel blockers to patients with frank cardiac failure or low-output states 1
• Discontinue NSAIDs in patients who routinely took them before STEMI due to increased adverse outcomes 1

Hemodynamic Management

• In inferior STEMI with right ventricular involvement, avoid nitrates and aggressive fluid resuscitation—both can precipitate hemodynamic collapse 2
• Do not use intravenous beta-blockers acutely in STEMI—they are Class III (harmful) 3

Surgical Timing

• Emergency CABG should not be performed in hemodynamically stable patients with small areas at risk 3
• Emergency CABG should not be performed after successful epicardial reperfusion but unsuccessful microvascular reperfusion 3

Systems of Care Considerations

Every community should have a written protocol guiding EMS personnel on destination decisions for STEMI patients 1. Networks providing 24/7 cardiac catheterization availability have demonstrated reduced time to reperfusion and improved mortality 4, 5.