Treatment of Acute Myocardial Infarction on ECG
For acute MI identified on ECG, immediate reperfusion therapy is mandatory: primary PCI within 120 minutes of first medical contact is the preferred strategy, or fibrinolytic therapy if this timeline cannot be achieved. 1
Immediate Actions
ECG Acquisition and Diagnosis
- Obtain and interpret 12-lead ECG within 10 minutes of first medical contact 1
- Activate STEMI protocol immediately upon identifying ST-segment elevation or new left bundle branch block
- Initiate continuous ECG monitoring with defibrillator capacity 1
Reperfusion Strategy Decision
The choice between primary PCI and fibrinolysis depends entirely on timing:
Primary PCI (Preferred)
- Must achieve first medical contact-to-device time ≤120 minutes 1, 2
- Ideal target is ≤90 minutes in urban settings 2
- Patients should bypass emergency departments and go directly to catheterization laboratory 1
- Door-in-door-out time at transferring hospitals should be ≤30 minutes 2
Fibrinolytic Therapy (When PCI Cannot Meet Timeline)
- Initiate as soon as possible if 120-minute PCI window cannot be met 1, 2
- Greatest benefit within first 2-3 hours of symptom onset 2
- Use fibrin-specific agents: tenecteplase, alteplase, or reteplase (Class I-B recommendation) 1
- Must be given within 12 hours of symptom onset 1, 2
Antithrombotic Therapy
Antiplatelet Therapy
Immediate Administration:
- Aspirin (oral or IV if unable to swallow) as soon as possible 1
- Potent P2Y12 inhibitor: prasugrel or ticagrelor preferred over clopidogrel 1
Important Caveat: P2Y12 inhibitors should NOT be routinely given in ambulances; administer in emergency department or catheterization laboratory unless transport time >60 minutes 2
Anticoagulation
For Fibrinolysis:
- Enoxaparin IV followed by subcutaneous (preferred over unfractionated heparin, Class I-A) 1
- Alternative: weight-adjusted UFH bolus followed by infusion (Class I-B) 1
- Continue until revascularization or up to 8 days of hospital stay 1
For Primary PCI:
- Fondaparinux is NOT recommended (Class III-B) 1
Post-Fibrinolysis Management
All patients receiving fibrinolysis require:
- Immediate transfer to PCI-capable center after fibrinolysis 1
- Angiography and PCI between 2-24 hours after successful fibrinolysis 1
- Emergency angiography if heart failure/shock develops 1
- Rescue PCI immediately if fibrinolysis fails (<50% ST-segment resolution at 60-90 minutes) or hemodynamic/electrical instability occurs 1
Adjunctive Medical Therapy
Acute Phase
- Avoid routine oxygen unless SaO2 <90% 1
- Avoid routine IV opioids; use selectively only for severe pain 2
- Avoid IV beta-blockers in patients with hypotension, acute heart failure, AV block, or severe bradycardia 1
Early Pharmacotherapy (Within 24 Hours)
- ACE inhibitors for patients with heart failure, LVEF <40%, diabetes, or anterior infarct 1
- High-intensity statin therapy as early as possible 1
- Oral beta-blockers for patients with heart failure and/or LVEF <40% 1
Long-Term Therapy
- Dual antiplatelet therapy (aspirin 75-100 mg + ticagrelor or prasugrel) for 12 months 1
- PPI if high gastrointestinal bleeding risk 1
- LDL-C goal <1.8 mmol/L (70 mg/dL) or ≥50% reduction 1
- MRAs if ejection fraction <40% with heart failure or diabetes (already on ACE inhibitor and beta-blocker, without renal failure/hyperkalemia) 1
Monitoring and Follow-Up
- Routine echocardiography during hospital stay to assess LV/RV function, detect mechanical complications, and exclude LV thrombus 1
- Cardiac rehabilitation program participation 1
- Smoking cessation with pharmacotherapy (nicotine replacement, varenicline, or bupropion) 1
Critical Pitfalls to Avoid
- Do not delay reperfusion for troponin results—ECG diagnosis drives immediate treatment
- Do not perform routine PCI of occluded infarct-related artery >48 hours after STEMI onset in asymptomatic patients 1
- Do not use fondaparinux for primary PCI 1
- Do not give IV beta-blockers in hemodynamically unstable patients 1