ECG criteria for ST Elevation Myocardial Infarction (STEMI)

The fastest way to diagnose myocardial infarction (MI) is by the ECG. No biomarker reacts on myocardial ischemia as quickly as the ECG does. The ECG changes almost simultaneously with the onset of coronary occlusion. Thus, it should be acquired and interpreted within 10 minutes after first medical contact.

How is myocardial infarction defined?

4th Universal Definition of Myocardial Infarction

The Executive Group on behalf of the Joint European Society of Cardiology (ESC)/American College of Cardiology (ACC)/ American Heart Association (AHA)/World Heart Federation (WHF) Task Force for the Universal Definition of Myocardial Infarction published this paper in the European Heart Journal in 2019.

The clinical definition for MI is the presence of acute myocardial injury detected by abnormal cardiac biomarkers in the setting of evidence of acute myocardial ischemia.

Generally there are 3 types of myocardial infarction. ST elevation myocardial infarction (STEMI) is usually categorized as type 1 MI. This means myocardial injury is caused by acute atherosclerotic plaque rupture or erosion. The culprit coronary artery often shows (sub-)total occlusion.

ECG criteria for STEMI

These criteria apply when symptoms of myocardial ischaemia are present.

1. New ST-elevation at the J-point in two contiguous leads

The cut-points are:

  • ≥ 1 mm in all leads other than leads V2–V3
  • V2-V3: ≥ 2mm in men ≥ 40 years; ≥ 2.5 mm in men < 40 years, or ≥ 1.5 mm in women regardless of age

2. Development of pathological Q waves (also a sign for prior MI in absence of acute symptoms)

ST-segment shifts showing high amplitudes in multiple leads or coronary territories are a sign of more myocardial ischaemia. Prognosis is worse in these cases.

Criteria for Left Main MI and Multivessel Disease

  • ST-segment elevation or depression greater than 1 mm in more than six leads
  • ST-segment elevation in leads aVR and / or lead V1
  • Hemodynamic compromise

ECG in patients with STEMI and left bundle branch block (LBBB)