Note that the first three account for almost 90% of ECG tracings with LAD. If the QRS is predominantly negative in lead I and positive in lead aVF, then the axis is rightward (right axis deviation).

In a “normal” electrocardiogram (ECG), the transition of the QRS axis in the precordial leads occurs between leads V 3 and V 4 (i.e., there is a dominant S in V 3 and a dominant R in V 4).

Left axis deviation occurs when the QRS axis falls between -30 and -90. There are a variety of causes, including left anterior fascicular block and left ventricular hypertrophy. See the ECG basics ...

Normal ECGs include common, training-related findings in athletes such as high QRS amplitude meeting ... pathological Q-waves, left axis deviation and conduction delays and findings suggestive or ...

These ECG voltage attenuations are of extracardiac mechanism, and impact the amplitude of QRS complexes, P-waves, and T-waves, occasionally resulting also in shortening of the QRS complex and QT ...