What is the initial treatment for a patient with ST-Elevation Myocardial Infarction (STEMI)?

Initial Treatment for ST-Elevation Myocardial Infarction (STEMI)

The initial treatment for STEMI should focus on rapid reperfusion therapy, with primary percutaneous coronary intervention (PCI) as the preferred strategy when it can be performed within 90 minutes of first medical contact, or fibrinolytic therapy within 30 minutes if PCI cannot be performed in a timely manner. 1, 2

Immediate Assessment and Stabilization

• Obtain a 12-lead ECG as soon as possible at first medical contact, with a maximum target delay of 10 minutes to confirm STEMI diagnosis 2
• Initiate continuous ECG monitoring with defibrillator capacity immediately in all patients with suspected STEMI 2
• Administer oxygen therapy only if oxygen saturation is <90% 2
• Perform a focused history and physical examination to identify contraindications to fibrinolytic therapy and assess for complications 1

Reperfusion Strategy Selection

• Primary PCI is the preferred reperfusion strategy when performed by an experienced team within 120 minutes of STEMI diagnosis 1, 2
• If PCI cannot be performed within 120 minutes, fibrinolytic therapy should be initiated immediately 2
• For patients transported by EMS to a PCI-capable hospital, the goal is to achieve EMS arrival-to-balloon time within 90 minutes 1
• For patients who self-transport to a PCI-capable hospital, the door-to-balloon time should be within 90 minutes 1
• For patients transported to a non-PCI-capable hospital, door-to-needle time for fibrinolytic therapy should be within 30 minutes 1

Primary PCI Strategy

• Transfer patients directly to the catheterization laboratory, bypassing the emergency department when possible 2
• Administer aspirin (oral 150-325 mg or IV 250-500 mg if unable to swallow) as soon as possible 2
• Administer a potent P2Y12 inhibitor (prasugrel or ticagrelor, or clopidogrel if these are unavailable) before or at the time of PCI 2
• Provide anticoagulation during PCI with unfractionated heparin (UFH) as an IV bolus at 100 U/kg (60 U/kg if GPIIb/IIIa inhibitors are used) 2

Fibrinolytic Strategy

• Initiate fibrinolytic therapy as soon as possible, preferably in the pre-hospital setting if available 2
• Use a fibrin-specific agent (tenecteplase, alteplase, or reteplase) 2
• Administer tenecteplase as a single weight-adjusted intravenous bolus of 30-50mg (0.53 mg/kg bodyweight) 2, 3
• For patients ≥75 years old, a 50% dose reduction of tenecteplase is recommended to reduce the risk of stroke 2
• Administer oral or IV aspirin along with clopidogrel 2
• Provide anticoagulation until revascularization or for the duration of hospital stay (up to 8 days) 2

Special Considerations

• Patients with cardiogenic shock should be immediately transferred to facilities capable of cardiac catheterization and rapid revascularization if it can be performed within 18 hours of onset of shock 1
• Patients with contraindications to fibrinolytic therapy should be immediately transferred to facilities capable of PCI 1
• Patients at high risk of dying, including those with severe congestive heart failure, should be considered for immediate transfer to PCI-capable facilities 1
• For patients with recurrent ischemic-type chest discomfort after initial reperfusion therapy, escalate medical therapy with nitrates and beta-blockers, and consider urgent cardiac catheterization 1

Common Pitfalls and Caveats

• Avoid delays in reperfusion therapy - "time is muscle" and every minute counts in preserving myocardial function 1, 2
• Recognize atypical presentations, especially in women, elderly, and diabetic patients, which may lead to delayed diagnosis 2
• Avoid facilitated PCI using full-dose fibrinolytic therapy followed by immediate PCI, as this strategy may be harmful 1
• Be cautious with bleeding risk - avoid intramuscular injections and nonessential handling of the patient for the first few hours following fibrinolytic therapy 3
• Monitor for reperfusion arrhythmias (sinus bradycardia, accelerated idioventricular rhythm, ventricular premature depolarizations, ventricular tachycardia) and have anti-arrhythmic therapy available 3

Remember that the overarching goal is to keep total ischemic time within 120 minutes (ideally within 60 minutes) from symptom onset to initiation of reperfusion treatment 1, 2.