23-40: Left Atrial Hypertrophy

ECG Findings

• Increased duration (width) of the P wave without affecting its upward amplitude (as commonly seen with right atrial abnormalities)

• Negative P-wave deflection in lead V₁, with width and depth > 40 ms

• Bifid P wave in lead II with total P duration > 110 ms and > 40 ms between two peaks

• Notched P wave in II, III, or aVF with duration ≥ 120 ms

Pearls

1. Normal P-wave morphology has an amplitude of < 2.5 mV (2.5 vertical boxes) and a duration (width) of <120 ms (three small boxes).

2. The left atrium depolarizes after the right atrium and therefore has the most effect on the 2nd portion of the P wave.

3. Causes of left atrial abnormality or P-mitrale include valvular heart disease (mitral and aortic), coronary artery disease, cardiomyopathy, hypertension, and LVH.