Table 1. Major Abnormalities And Minor 12-Lead ECG Variations Based On Minnesota Coding.

Major ECG abnormality	Minor ECG variations
Q-wave abnormalities	Borderline Q waves
ST-segment depression	Left- or right-axis deviation
T-wave inversion	High-amplitude R waves
2o or 3o AV block	Borderline ST-segment depression
Complete LBBB or RBBB	T-wave flattening
Frequent premature atrial or ventricular beats	Low QRS voltage
Atrial fibrillation or flutter

AV = atrio-ventricular; LBBB = left bundle branch block; RBBB = right bundle branch block. (Adapted from de Bacquer et al., 1998).¹⁹