What is the management for ST elevation on an electrocardiogram (EKG)?

Management of ST Elevation on EKG

ST elevation on an electrocardiogram (EKG) requires immediate reperfusion therapy, preferably with primary percutaneous coronary intervention (PCI) within 90 minutes of first medical contact, or fibrinolysis within 30 minutes if timely PCI is not available. 1, 2

Diagnosis of STEMI

Diagnostic Criteria

• ST elevation at the J point in at least 2 contiguous leads:
  • ≥2 mm (0.2 mV) in men or ≥1.5 mm (0.15 mV) in women in leads V2–V3
  • ≥1 mm (0.1 mV) in other contiguous chest leads or limb leads 2
• New or presumed new left bundle-branch block (LBBB) should not be considered diagnostic of acute MI in isolation 2
• Additional ECG leads to consider:
  • V7-V9 for posterior MI detection
  • V3R-V4R for right ventricular involvement 2, 1

STEMI Equivalents Requiring Same Management

• Isolated posterior MI (ST depression in V1-V3 with upright T waves)
• ST depression with ST elevation in aVR suggesting left main or multivessel disease
• De Winter pattern (indicating proximal LAD occlusion) 2, 1

Immediate Actions

1. Obtain 12-lead ECG within 10 minutes of first medical contact 1
2. Establish IV access
3. Administer aspirin 325 mg loading dose 1
4. Provide oxygen only if oxygen saturation <90% 1
5. Relieve pain with IV opioids (morphine 4-8 mg with additional doses of 2 mg at 5-15 min intervals) 2
6. Perform rapid risk stratification to determine reperfusion strategy

Reperfusion Strategy Decision Algorithm

Primary PCI Preferred When:

• PCI-capable facility available with first medical contact-to-device time ≤90 minutes
• Cardiogenic shock or Killip class ≥III heart failure
• Contraindications to fibrinolysis
• Late presentation (>3 hours from symptom onset)
• Diagnosis of STEMI is uncertain 2, 1

Fibrinolysis Preferred When:

• Early presentation (<3 hours from symptom onset)
• PCI not available within 90-120 minutes
• No contraindications to fibrinolysis 2, 1

Additional Management

Antiplatelet and Anticoagulation

• Dual antiplatelet therapy:
  • Aspirin 325 mg loading dose, then 75-150 mg daily
  • P2Y12 inhibitor (clopidogrel 300-600 mg loading dose, then 75 mg daily) 1
• Anticoagulation with unfractionated heparin, low molecular weight heparin, or bivalirudin 1

Monitoring

• Continuous cardiac monitoring for arrhythmias
• Serial ECGs if initial ECG is non-diagnostic but clinical suspicion remains high
• Echocardiography to assess wall motion abnormalities and left ventricular function 1

Special Considerations

Left Bundle Branch Block

• New or presumably new LBBB should not automatically trigger reperfusion therapy
• Look for specific criteria suggesting acute MI in the setting of LBBB
• If clinical suspicion is high with new LBBB, consider emergency angiography 2

Ventricular Paced Rhythm

• May obscure ST-segment interpretation
• Consider reprogramming pacemaker if patient is not pacemaker-dependent
• When in doubt with strong clinical suspicion, proceed to emergency angiography 2

Isolated Posterior MI

• ST depression in V1-V3 with upright T waves
• Additional posterior leads (V7-V9) may show ST elevation
• Should be treated as STEMI 2

Left Main/Multivessel Disease

• ST depression >0.1 mV in ≥8 surface leads with ST elevation in aVR/V1
• Associated with high mortality (31% vs 6.2% for typical STEMI) 3
• Requires urgent rather than emergent catheterization 3

Pitfalls to Avoid

1. Waiting for biomarker results before initiating reperfusion therapy 1
2. Relying solely on computer ECG interpretation 1
3. Missing STEMI with normal initial ECG (up to 6% of cases) - perform serial ECGs 1
4. Misdiagnosing ST elevation due to LV aneurysm as acute MI - consider T-wave to QRS amplitude ratio (>0.36 in any lead V1-V4 suggests acute MI) 4
5. Delaying transfer to PCI-capable centers when indicated 1

Remember that early diagnosis and immediate reperfusion are the most effective ways to limit myocardial ischemia, reduce infarct size, and decrease the risk of post-STEMI complications and heart failure 5.