Initial Treatment for ST-Elevation Myocardial Infarction (STEMI)
Primary percutaneous coronary intervention (PCI) is the recommended initial treatment for STEMI when it can be performed in a timely fashion by experienced operators. 1
Immediate Actions and Reperfusion Strategy
- Obtain a 12-lead ECG promptly when STEMI is suspected, as minimizing time to reperfusion is critical 2
- Reperfusion therapy should be administered to all eligible patients with STEMI with symptom onset within the prior 12 hours 1
- Primary PCI is the preferred reperfusion strategy when it can be performed in a timely fashion by experienced operators 1, 3
- The goal for primary PCI is balloon inflation within 90 minutes of first medical contact 1, 2
- If PCI cannot be performed within 120 minutes of STEMI diagnosis, fibrinolytic therapy should be administered 1, 4
- When fibrinolytic therapy is indicated or chosen as the primary reperfusion strategy, it should be administered within 30 minutes of hospital arrival 1
Prehospital Management
- EMS should perform a 12-lead ECG at the site of first medical contact in patients with symptoms consistent with STEMI 1
- Prehospital administration of aspirin via EMS personnel is reasonable in patients with symptoms suggestive of STEMI 1
- EMS transport directly to a PCI-capable hospital for primary PCI is the recommended triage strategy, with a first medical contact-to-device time goal of 90 minutes or less 1
- Every community should have a written protocol that guides EMS system personnel in determining where to take patients with suspected or confirmed STEMI 1
Pharmacological Therapy
- Immediate antithrombotic therapy:
- Aspirin (75-325 mg) should be administered as soon as possible 1, 5
- A P2Y12 inhibitor (such as clopidogrel or prasugrel) should be added to aspirin therapy 1, 5
- Prasugrel is initiated as a single 60 mg oral loading dose followed by 10 mg once daily, but is contraindicated in patients with prior stroke or TIA 5
- Anticoagulation therapy:
Special Circumstances
- Patients with STEMI who have cardiogenic shock and are less than 75 years of age should be brought immediately to facilities capable of rapid revascularization 1
- Patients with STEMI who have contraindications to fibrinolytic therapy should be brought immediately to facilities capable of cardiac catheterization and rapid revascularization 1
- For late-presenting patients (12-24 hours after symptom onset), reperfusion therapy is reasonable if there is clinical and/or ECG evidence of ongoing ischemia 1
Adjunctive Therapies
- Beta-blockers should be administered to patients without contraindications (avoid in patients with low cardiac output due to pump failure) 1
- ACE inhibitors should be given to patients with pulmonary edema unless systolic blood pressure is less than 100 mm Hg 1
- Statins should be initiated early as they reduce both short and long-term adverse outcomes 1
- Nitrates are useful only for the treatment of recurrent angina but should not be used if hypotension limits the administration of beta-blockers or ACE inhibitors 1
Common Pitfalls and Caveats
- Delays in reperfusion therapy significantly increase mortality - "time is muscle" 3
- Failure to recognize STEMI in patients with atypical presentations can lead to delayed treatment 6
- Overreliance on primary PCI may lead to unnecessary delays when fibrinolysis would be more appropriate due to transport times 1
- Patients with STEMI and cardiogenic shock are high-priority cases and require immediate intervention 1
- For the small fraction of patients requiring urgent CABG after antiplatelet therapy, the risk of significant bleeding is substantial 5
Remember that the most important principle in STEMI management is the appropriate and timely use of some form of reperfusion therapy, with the greatest emphasis placed on delivering reperfusion as rapidly as possible to minimize myocardial damage 1, 3.