Left atrial enlargement electrocardiogram

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [3]

Left atrial enlargement may be observed among patients with pressure or volume overload of the left atrium.

• Atrial aneurysm
• Infective endocarditis
• Left heart failure
• Mitral regurgitation
• Mitral stenosis
• Mitral valve prolapse
• Myxedema
• Patent Ductus Arteriosus
• Ventricular septal defect

Left atrial enlargement produces a broad, bifid P wave in lead II (P mitrale) and enhances the terminal negative portion (negative deflection) of the P wave in V1.

In lead I and/or II the following may be seen:

• Bifid P wave with > 40 ms between the two peaks
• Total P wave duration > 110 ms

In lead V1, the following may be seen:

• Biphasic P wave with terminal negative portion > 40 ms duration (>0.04 sec or 1 small square)
• Biphasic P wave with terminal negative portion > 1mm deep

• Left atrial enlargement chest x-ray
• Left atrial enlargement causes

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