of the left atrium. The left atrium can be “stretched” from a number of different
causes, including increased volume (mitral regurgitation) or increased pressure
(left ventricular hypertrophy, left ventricular failure).
The ECG mainfestation of left atrial enlargement is a negative P wave in lead V1.
The magnitude of the negative deflection must be 1 small box by 1 small box.
It is said that “if you can fit a small box and have it sit inside the P wave in
V1” - you have LAE.
