Left Atrial Enlargement

Left Atrial Enlargement

Left atrial enlargement (LAE) is due to pressure or volume overload of the left atrium. LAE is often a precursor to atrial fibrillation.

Also known as: Left Atrial Enlargement (LAE), Left atrial hypertrophy (LAH), left atrial abnormality.

P wave changes with Left Atrial Enlargement
P wave morphology LAE Wagner 2007

ECG Criteria for Left Atrial Enlargement

LAE produces a broad, bifid P wave in lead II (P mitrale) and enlarges the terminal negative portion of the P wave in V1.

In lead II

  • Bifid P wave with > 40 ms between the two peaks
  • Total P wave duration > 110 ms

In V1

  • Biphasic P wave with terminal negative portion > 40 ms duration
  • Biphasic P wave with terminal negative portion > 1mm deep

Causes of left atrial hypertrophy

In isolation:

  • Classically seen with mitral stenosis

In association with left ventricular hypertrophy:

  • Systemic hypertension
  • Aortic stenosis
  • Mitral incompetence
  • Hypertrophic cardiomyopathy

ECG Examples

Example 1
ECG strip bifid P wave p mitrale
  • Broad (>110ms), bifid P wave in lead II (P mitrale) with > 40ms between the peaks

Example 2

P wave terminal portion
P wave terminal portion > 40 ms duration in V1

Example 3

P waves with terminal portion more than 1mm deep in V1
P waves with terminal portion > 1mm deep in V1

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Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Adult/Paediatric Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner

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