Conduction abnormality within the right and left atrium, which may be due to both right and left atrial enlargement (dilation), or right and left atrial hypertrophy (thickening).

-Combination of criterial for right atrial abnormality and left atrial abnormality.

-Right atrial abnormality:

-P wave 2 (inferior leads):       >2.5 mm tall; >2 boxes wide; peaked.

-P waves V1:                              >1.5 mm tall.

-Left atrial abnormality:

-P wave V1:                                >1 box deep; >1 box wide.

-P wave 2:                                  >0.12 sec (3 boxes); notched.