What are the ST-Elevation Myocardial Infarction (STEMI) criteria?

From the Guidelines

STEMI criteria are met when there is new ST-segment elevation at the J-point in at least two contiguous leads of ≥2 mm (0.2 mV) in men or ≥1.5 mm (0.15 mV) in women in leads V2-V3, or ≥1 mm (0.1 mV) in other contiguous chest or limb leads, as recommended by the 2018 European Society of Cardiology guidelines 1.

Key Points

• New left bundle branch block (LBBB) with appropriate clinical context was traditionally considered a STEMI equivalent, though this is now more nuanced with specific criteria like Sgarbossa criteria being applied 1.
• Other STEMI equivalents include ST depression in leads V1-V3 suggesting posterior MI and ST elevation in lead aVR suggesting left main coronary artery occlusion 1.
• These ECG changes reflect transmural myocardial injury from complete coronary artery occlusion, causing full-thickness damage to the heart muscle.
• Immediate reperfusion therapy is indicated, ideally primary percutaneous coronary intervention (PCI) within 90 minutes of first medical contact, or fibrinolytic therapy within 30 minutes if PCI is not available within 120 minutes, as recommended by the 2017 AHA/ACC guidelines 1.

Diagnosis and Treatment

• A working diagnosis of STEMI must first be made, usually based on symptoms consistent with myocardial ischaemia and signs on a 12-lead electrocardiogram (ECG) 1.
• A reduction in chest pain after nitroglycerin administration can be misleading and is not recommended as a diagnostic manoeuvre 1.
• ECG monitoring should be initiated as soon as possible in all patients with suspected STEMI to detect life-threatening arrhythmias and allow prompt defibrillation if indicated 1.

Recommendations

• Reperfusion therapy should be administered to all eligible patients with STEMI with symptom onset within the prior 12 hours, as recommended by the 2017 AHA/ACC guidelines 1.
• Primary PCI is the recommended method of reperfusion when it can be performed in a timely fashion by experienced operators 1.
• EMS transport directly to a PCI-capable hospital for primary PCI is the recommended triage strategy for patients with STEMI, with an ideal FMC-to-device time system goal of 90 minutes or less 1.

From the Research

STEMI Criteria

• STEMI (ST-segment elevation myocardial infarction) is a major cause of morbidity and mortality worldwide, and its treatment involves emergent reperfusion of the infarct-related artery to salvage myocardium and improve cardiovascular outcome 2.
• The diagnosis of STEMI is typically made using electrocardiogram (ECG) criteria, including persistent ST-segment elevation or presumably new left bundle branch block 3.
• Reperfusion strategies for STEMI include fibrinolysis, primary percutaneous coronary intervention (PCI), or a combination of both methods 2.

Reperfusion Therapy

• Primary PCI is the preferred reperfusion strategy for STEMI patients if it can be performed within 120 minutes of first medical contact (FMC) 4, 5.
• If primary PCI cannot be performed within 120 minutes, fibrinolysis therapy should be administered to dissolve the occluding thrombus 5.
• The American and European guidelines recommend that reperfusion therapy should be initiated as soon as possible after FMC, with a goal of achieving reperfusion within 120 minutes of FMC 4.

Time Delays

• The time delay between the onset of symptoms and FMC is critical, and efforts should be made to keep this interval as short as possible 3.
• The time delay between FMC and the beginning of reperfusion therapy is also crucial, and primary PCI should be preferred if it can be performed within 120 minutes of FMC 4, 3.
• In patients under 75 years presenting with a large anterior infarction within 2 hours after onset of symptoms, the time interval between FMC and primary PCI should not exceed 90 minutes 3.

Fibrinolysis vs. Primary PCI

• Fibrinolysis is recommended when primary PCI is associated with a delay of ≥120 minutes from FMC 4.
• Primary PCI is superior to fibrinolysis in reducing mortality if the extra time needed to perform PCI instead of fibrinolysis (PCI-related delay) is <120 minutes 4.
• The choice between fibrinolysis and primary PCI depends on the expected PCI-related delay and the patient's individual characteristics 6.