Criteria

ST changes on ECG[2][4]

New or presumed new ST-segment elevation at the J point in 2 or more contiguous leads with the cutoff points of ≥1 mm in all leads other than V2, or V3, where the following cutoff points apply:

  • ≥2.5 mm in men <40 years old

  • ≥2 mm in men >40 years old

  • ≥1.5 mm in women regardless of age

New horizontal or downsloping ST-depression ≥0.5 mm in two contiguous leads and/or T-wave inversion >1 mm in two contiguous leads with prominent R wave or R/S ratio >1. Note: ST depressions in leads V1-V4 should be considered as a posterior STEMI.

New or presumed new left bundle branch block (LBBB) in patients with coronary ischemia may be associated with poor prognosis. More importantly, the presence of LBBB on baseline ECG may confound the diagnosis of STEMI. In patients with new left bundle branch block, ≥1mm concordant ST-segment elevation may be an indicator of myocardial ischemia.

Criteria for acute, evolving, or recent myocardial infarction[2][4]

Either one of the following criteria:

1. Typical rise of biomarkers of myocardial necrosis (e.g., troponin) with at least one of the following:

  • Ischemic symptoms

  • Development of pathologic Q waves on ECG

  • ECG changes indicative of ischemia (ST-segment elevation or depression)

  • Coronary artery intervention (e.g., coronary angiography).

2. Pathologic findings of acute myocardial infarction (MI).

Criteria for established MI[2][4]

Any one of the following:

1. Development of pathologic Q waves on serial ECGs. The patient may or may not remember previous symptoms. Biochemical markers of myocardial necrosis may have normalized, depending on the length of time that has passed since the infarct developed.

2. Pathologic findings of a healed or healing MI.

3. Cardiac magnetic resonance imaging with the delayed enhancement imaging showing a classic subendocardial or transmural infarct in a coronary artery distribution.

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