Common to have TWI in I and aVL but should be in both
If only aVL, very likely reciprocal change at the start of inf MI
Most commonly used criteria
Lead I: R wave > 14 mm
Lead aVR: S wave > 15 mm
Lead aVL: R wave > 12 mm
Lead aVF: R wave > 21 mm
Lead V5: R wave > 26 mm
Lead V6: R wave > 20 mm
V4-V6 precordial leads may show ST depression & T wave inversions known as the LV Strain pattern
Diagnostic  ≥ 5 points and probable ≥ 4 points)
ST-T vector opposite to QRS without digitalis
ST-T vector opposite to QRS with digitalis
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Left ventricular hypertrophy
Right atrial enlargement
Right ventricular hypertrophy
Left atrial enlargement
Pericarditis
Cardiac hypertrophy and enlargement
Stone heart
Aortic stenosis