Thrombosed cor triatriatum sinistrum mimicking left atrial mass and causing unilateral pulmonary edema.

46 year old female with history of progressive shortness of breath for 3 years associated with recurrent right lung infiltrates and hemoptisis. A computed tomography of the chest showed a left atrial mass suggestive of atrial myxoma confirmed with transesophageal echocardiogram. Contrary with findings from a dedicated EKG gated cardiac computed tomography suggestive of cor triatriatum with associated thrombus and less likely a neoplasm; findings later on confirmed during surgery. Cardiac CT offers superior spatial resolution and multi-planar image reconstructions, allowing improved characterization of cardiac structures and cardiac masses compared to other traditional cardiovascular imaging modalities.