ST Elevation Myocardial Infarction Diagnosis Criteria

Standard Criteria by Lead Location

The European Society of Cardiology recommends that for STEMI diagnosis and reperfusion therapy, ST elevation is significant when measured at the J-point in at least two contiguous leads with the following thresholds: ≥2.5 mm in men <40 years, ≥2 mm in men ≥40 years, or ≥1.5 mm in women in leads V2-V3, and ≥1 mm in all other leads 1
Men ≥40 years should have ≥2 mm (0.2 mV) elevation in V2-V3, according to the American College of Cardiology 1, 2
Men <40 years should have ≥2.5 mm (0.25 mV) elevation in V2-V3, as stated by the European Heart Journal 1
Women (all ages) should have ≥1.5 mm (0.15 mV) elevation in V2-V3, as recommended by the European Society of Cardiology 1
All other precordial leads (V4-V6) should have ≥1 mm elevation in all patients, according to the European Heart Journal 1

ST elevation is measured at the J-point (junction of QRS complex and ST segment), with standard ECG calibration of 10 mm/mV, so 1 mm = 0.1 mV, as stated by the European Heart Journal 1
Requires elevation in at least two anatomically contiguous leads, as recommended by the European Society of Cardiology and the American College of Cardiology 1, 3, 4

Right precordial leads V3R-V4R should be recorded in all inferior MI cases, with significant elevation defined as ≥1 mm in right-sided leads, as stated by the European Heart Journal 1
Posterior MI (circumflex territory) can be identified by ST depression ≥0.5 mm in V1-V3 with upright terminal T-waves, and confirmed with posterior leads V7-V9 showing ≥0.5 mm elevation, as recommended by the European Society of Cardiology and the American Heart Association 1, 5

Non-diagnostic ST elevation (<1 mm) is considered non-specific, and these changes are less reliable and often seen in patients without acute coronary syndrome, as stated by the European Heart Journal 6, 7
However, do not exclude ACS—repeat ECGs and monitor for dynamic changes, as recommended by the European Society of Cardiology 1

ST depression >1 mm in two contiguous leads indicates high-risk unstable angina or NSTEMI, and do not give fibrinolytics for isolated ST depression (increased mortality risk) unless posterior MI suspected, as stated by the European Heart Journal and the American College of Cardiology 3, 4, 6, 7, 8
Deep symmetrical T-wave inversion in anterior leads suggests proximal LAD stenosis, as recommended by the European Society of Cardiology 6, 7
The extent of ST elevation correlates with infarct size, and research demonstrates a gradient of risk based on ECG abnormality severity, with ST elevation carrying higher mortality than ST depression or T-wave changes alone, as stated by the American Heart Association 5

Men ≥ 40 years: ST‑elevation ≥ 2.0 mm (0.2 mV) in leads V2‑V3 is required for STEMI diagnosis. 9
Men < 40 years: ST‑elevation ≥ 2.5 mm (0.25 mV) in leads V2‑V3 is required for STEMI diagnosis. 9
Women (all ages): ST‑elevation ≥ 1.5 mm (0.15 mV) in leads V2‑V3 is required for STEMI diagnosis. 9
All other standard leads (I, II, III, aVF, aVL, V4‑V6): ST‑elevation ≥ 1.0 mm (0.1 mV) in at least two anatomically contiguous leads is required. 9
Posterior leads V7‑V9: ST‑elevation ≥ 0.5 mm (0.05 mV) confirms posterior wall STEMI when paired with reciprocal changes. 9

J‑point measurement: ST‑elevation must be measured at the J‑point (junction of QRS complex and ST segment) relative to the PR‑segment baseline; ECG calibration is 10 mm/mV (1 mm = 0.1 mV). 9
Timing of measurement: Measuring ST‑elevation 60 ms after the J‑point yields significantly higher values (mean difference ≈ 5 mm in anterior MI); guideline recommendations specify J‑point measurement to avoid over‑estimation. 9

Anatomically contiguous leads: ST‑elevation must be present in ≥ 2 contiguous leads (e.g., anterior V1‑V6, inferior II, III, aVF, lateral I, aVL, V5‑V6, septal V1‑V2) to qualify as STEMI, reducing false‑positives from artifacts or normal variants. 9

ST‑elevation < 1 mm in non‑precordial leads or below the sex/age‑specific thresholds in V2‑V3 is considered non‑specific and unreliable for STEMI diagnosis; serial ECGs (5‑10 min intervals) are recommended to detect evolving changes. 10

Posterior MI pattern: Isolated ST‑depression ≥ 0.5 mm in V1‑V3 with upright terminal T‑waves suggests posterior wall STEMI; confirmation with posterior leads V7‑V9 showing ≥ 0.5 mm elevation mandates urgent reperfusion. 10
New or presumed new left bundle‑branch block (LBBB): Presence of a new LBBB with ischemic symptoms is a STEMI equivalent that requires immediate catheter‑based reperfusion, irrespective of specific ECG criteria. 11

Higher mortality with ST‑elevation: Patients presenting with ST‑elevation have a higher mortality risk compared with those showing only ST‑depression or isolated T‑wave changes. 10
ST‑depression ≥ 1 mm in ≥ 2 contiguous leads: Indicates high‑risk NSTEMI/unstable angina and warrants urgent catheterization, but fibrinolytic therapy is contraindicated unless posterior MI is confirmed. 10