Left Atrial Enlargement

A frontal chest radiograph shows double density to the right of the spine (short arrows) and convex border of the left atrial appendage (long arrows).

A lateral view of the chest shows posterior displacement of the left mainstem bronchus by an enlarged left atrium (arrowheads).

Signs of Left Atrial Enlargement (LAE) on Chest Radiography

• Convex left atrial appendage
• Double density on the right side of the spine (one of the earliest signs)
• Double density on the left side as the left atrium extends into the left lower lobe
• Posterior displacement of the left mainstem bronchus posteriorly on lateral view, and superiorly on frontal view
• Spreading of the carina

Common Causes of LAE

• Acquired: mitral valve disease (stenosis or regurgitation), left ventricular failure, left atrial myxoma
• Congenital: VSD, PDA, hypoplastic left heart complex

Our case: severe mitral regurgitation

Reference:

Miller SW, Boxt LM, Abbara S. Cardiac Imaging the Requisites, 2009, 3rd edition.