The morphology of the P wave will not be similar to the sinus P wave, which is normally upright in lead II and biphasic in lead V1. Often, the P wave is inverted in lead II, if it can be seen at all.

For biphasic P waves, both positive and negative deflections ... P-wave duration in any lead was >120 ms on a standard 12 lead ECG. To determine occurrence of SCD, all fatal coronary heart disease ...