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

• The P Wave
• Right Atrial Enlargement
• Biatrial Enlargement
• Left Ventricular Hypertrophy

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