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

Further Reading

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 (2nd 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.
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