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
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
- Broad (>110ms), bifid P wave in lead II (P mitrale) with > 40ms between the peaks
Example 2
Example 3
Related Topics
References
- Edhouse J, Thakur RK, Khalil JM. ABC of clinical electrocardiography. Conditions affecting the left side of the heart. BMJ. 2002 May 25;324(7348):1264-7. PMC1123219
- Chung DC, Nelson HM. ECG – A Pictorial Primer [internet].
LITFL Further Reading
- ECG Library Basics – Waves, Intervals, Segments and Clinical Interpretation
- ECG A to Z by diagnosis – ECG interpretation in clinical context
- ECG Exigency and Cardiovascular Curveball – ECG Clinical Cases
- 100 ECG Quiz – Self-assessment tool for examination practice
- ECG Reference SITES and BOOKS – the best of the rest
Advanced Reading
- Brady WJ, Truwit JD. Critical Decisions in Emergency and Acute Care Electrocardiography
- Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric
- Wagner GS. Marriott’s Practical Electrocardiography 12e
- Chan TC. ECG in Emergency Medicine and Acute Care
- Rawshani A. Clinical ECG Interpretation
- Mattu A. ECG’s for the Emergency Physician
- Hampton JR. The ECG In Practice, 6e

ECG LIBRARY
Electrocardiogram
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