Biatrial Enlargement

Biatrial Enlargement Definition

Biatrial enlargement is diagnosed when criteria for both right and left atrial enlargement are present on the same ECG.

The diagnosis of biatrial enlargement requires criteria for LAE and RAE to be met in either lead II, lead V1 or a combination of leads.

ECG Criteria for Biatrial Enlargement

The spectrum of P-wave changes in leads II and V1 with right, left and bi-atrial enlargement is summarized below:

In lead II

Bifid P wave with

  • Amplitude ≥ 2.5mm AND
  • Duration ≥ 120 ms

In V1

Biphasic P waves with

  • Initial positive deflection ≥ 1.5mm tall AND
  • Terminal negative deflection ≥ 1mm deep AND
  • Terminal negative deflection ≥ 40 ms duration

Combination criteria

  • P wave positive deflection ≥ 1.5 mm in leads V1 or V2 AND
  • Notched P waves with duration >120 ms in limb leads, V5 or V6

P wave changes with Biatrial Enlargement
P wave morphology LAE RAE BAE Wagner 2007

Causes of Biatrial Enlargement

Combination of both left and right atrial enlargement.

Right atrial enlargement

  • Pulmonary hypertension due to:
  • Chronic lung disease (cor pulmonale)
  • Tricuspid stenosis
  • Congenital heart disease (pulmonary stenosis, Tetralogy of Fallot)
  • Primary pulmonary hypertension

Left Atrial Enlargement

  • Mitral valve disease
  • Aortic valve disease
  • Hypertension
  • Aortic stenosis
  • Mitral incompetence
  • Hypertrophic cardiomyopathy (HOCM)

ECG Examples

Example 1
ECG biatrial enlargement 1

Biatrial enlargement due to idiopathic cardiomyopathy:

  • Biphasic P waves in V1 with a very tall positive deflection (almost 3 mm in height!) and a negative deflection that is both deep (> 1 mm) and wide (> 40 ms).

Example 2

ECG biatrial enlargement 2

Biatrial enlargement:

  • P waves in lead II are tall (> 2.5mm) and wide (> 120 ms).
  • P waves in V2 are tall (> 1.5 mm), while the terminal negative portion of V1 is deep (> 1mm) and wide (> 40 ms).

Related Topics


  • Chung DC, Nelson HM. ECG – A Pictorial Primer [internet].
  • 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. PMID: 12028984; PMC1123219
  • Harrigan RA, Jones K. ABC of clinical electrocardiography. Conditions affecting the right side of the heart. BMJ. 2002 May 18;324(7347):1201-4. PMID: 12016190; PMC1123164

LITFL Further Reading

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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 |

One comment

  1. I need to thank you for the ECG Library. It’s helping me a lot! I’m from Brazil, still on my way through med school. And at every cardiology class, I feel stupid looking at the ECGs and listening to the teacher. He talks as if we students understand ECG, but we don’t. And now I get it. It’s a huuuge subject, and a difficult one to explain. So… Just wanted to say thanks, because these posts have been really helpful to me, and the links and references… amazing! Now I’m actually learning ECG!

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