Left atrial enlargement on chest radiography (illustration)

The following are the radiologic signs of left atrial enlargement on frontal chest radiographs:

• double density sign
• distance of the right border of the left atrium from the midpoint of the left mainstem bronchus is more than 7 cm
• enlarged left atrial appendage (third mogul sign)
• uplifted left mainstem bronchus
• widening of the carinal angle (more than 90 degrees)
• atrial escape (the right border of the markedly enlarged left atrium goes beyond the right atrial margin)

On lateral chest radiographs, an enlarged left atrium results to:

• prominence of the upper posterior cardiac convexity
• posterior displacement of the left mainstem bronchus (walking man sign)