Left Atrial Enlargement

AKA: Left atrial hypertrophy, left atrial abnormality.

Attention! Before reading this page, check out our introduction to the P wave for an explanation of the basics of atrial enlargement.

Background

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

Electrocardiographic Criteria

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

Diagnostic criteria are as follows:

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

In isolation:

• Classically seen with mitral stenosis

In association with left ventricular hypertrophy:

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

Examples

Broad (>110ms), bifid P wave in lead II (P mitrale) with > 40ms between the peaks

P wave terminal portion > 40 ms duration in V1

P waves with terminal portion > 1mm deep in V1

Related Topics

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

Further Reading

• ECG BASICS – Waves, Intervals, Segments and Clinical Interpretation
• ECG CLINICAL CASES – Your favourite ECG’s placed in clinical context with a challenging Q&A approach
• ECG and Cardiology Eponymous Syndromes – Cheats guide to eponymous emancipation
• ECG Reference Sites on the WEB – the best of the rest

Author Credits

References

• Chung DC, Nelson HM. ECG – A Pictorial Primer [internet]. Accessed 12/12/2011.
• 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. Review. PubMed PMID: 12028984; PubMed Central PMCID: PMC1123219 [Full Text].
• Harrigan RA, Jones K. ABC of clinical electrocardiography. Conditions affecting the right side of the heart. BMJ. 2002 May 18;324(7347):1201-4. Review. PubMed PMID: 12016190; PubMed Central PMCID: PMC1123164 [Full Text].
• Jenkins RD, Gerred SJ. ECGs by Example. Second Edition. Elsevier Churchill Livingstone 2005.
• Phibbs, BP. Advanced ECG: Boards and Beyond (2^nd Edition), Saunders Elsevier 2006.
• Surawicz B, Knilans TK. Chou’s Electrocardiography in Clinical Practice. 6th Edition. Saunders Elsevier 2008.
• Wagner, GS. Marriott’s Practical Electrocardiography (11th edition), Lippincott Williams & Wilkins 2007.