Table 1. Definition of the ECG abnormal categories.
| MC* | Definition | |
|---|---|---|
| Axial abnormality (Left axis deviation OR Clockwise rotation) | ||
| MC 2–1. | QRS axis from -300 through -900 in leads I, II, III (The algebraic sum of major positive and major negative QRS waves must be zero or positive in I, negative in III, and zero or negative in II) | |
| MC 9-4-2. | QRS transition zone at V4 or to the left of V4 on the chest. | |
| Structural abnormality (Left ventricular hypertrophy OR Atrial enlargement) | ||
| MC 3–1. | High amplitude R waves, Left: R amplitude > 26 mm in either V5 or V6, or R amplitude > 20.0 mm in any of leads I, II, III, aVF, or R amplitude > 12.0 mm in lead aVL (Measured only on second to last complete normal beat) | |
| MC 3–3. | High amplitude R waves, Left (optional code when 3–1 is not present): R amplitude > 15.0 mm but ≤ 20.0 mm in lead I, or R amplitude in V5 or V6, plus S amplitude in V1 > 35.0 mm. (Measured only on second to last complete normal beat) | |
| MC 9–3. | P-wave amplitude ≥ 2.5 mm in any of leads II, III, aVF, in a majority of beats) | |
| Repolarization abnormality (Minor and Major ST–T changes) | ||
| MC 4-1-1. | STJ depression ≥ 2.0 mm and ST segment horizontal or downward sloping in the anterolateral site or the anterior site | |
| MC 4-1-2. | STJ depression ≥ 1.0 mm but < 2.0 mm, and ST segment horizontal or downward sloping in the anterolateral site or the anterior site | |
| MC 4–2. | STJ depression ≥ 0.5 mm and < 1.0 mm and ST segment horizontal or downward sloping in the anterolateral site or the anterior site, | |
| MC 4–3. | No STJ depression as much as 0.5 mm but ST segment downward sloping and segment or T-wave nadir ≥ 0.5 mm below P-R baseline, in the anterolateral site or the anterior site | |
| MC 4–4. | STJ depression ≥ 1.0 mm and ST segment upward sloping or U-shaped, in the anterolateral site or the anterior site, MC 5–1. T amplitude negative 5.0 mm or more when R amplitude is ≥ 5.0 mm | |
| MC 5–2. | T amplitude negative or diphasic (positive-negative or negative-positive type) with negative phase at least 1.0 mm but not as deep as 5.0 mm when R amplitude is ≥ 5.0 mm | |
| MC 5–3. | T amplitude zero (flat), or negative, or diphasic (negative-positive type only) with less than 1.0 mm negative phase when R amplitude is ≥ 5.0 mm, MC 5–4. T amplitude positive and T/R amplitude ratio < 1/20: R wave amplitude must be ≥ 10.0 mm) abnormalities. | |
*MC = Minnesota code