What is an expected ECG finding in a patient with left atrial enlargement?

In patients with left atrial enlargement, one of the hallmark electrocardiogram (ECG) findings is the presence of notched P waves, particularly noted in leads I and II. This is because the enlargement of the left atrium leads to prolonged conduction time through the atrial tissue, resulting in the characteristic delay in atrial depolarization. This prolonged activation manifests as a notched appearance in the P waves on the ECG, often described as a "M-shaped" or "bifid" P wave.

The elevation in the amplitude and duration of the P wave provides important diagnostic information regarding the presence of left atrial enlargement, and it's a key component in assessing atrial size and function. This feature can be crucial for diagnosing conditions that lead to left atrial overload, such as hypertension, valvular heart disease, or heart failure.

Other features that may appear in left atrial enlargement, such as changes in time intervals or waveforms, do not exhibit the same specific relationship with left atrial hypertrophy as the notched P waves do.