Left atrial diverticulum-An unexpected finding in routine transesophageal echocardiography.

We report a 55-year-old male patient with lone paroxysmal atrial fibrillation who underwent routine transesophageal echocardiography (TOE) at our institution. In a mid-esophageal 125° three-chamber angulation, a distinct thinning of the left atrial (LA) wall was observed, forming a 7 × 4 mm canal with only a small membrane separating the LA from the pericardial space. Cardiac magnetic resonance imaging diagnosed a small LA diverticulum. To the best of our knowledge, this is the first manuscript describing detection of a small LA diverticulum via TOE.