Inadvertent coexistence of atrial myxoma and mitral stenosis

A 59-year-old woman was referred for evaluation of shortness of breath. Physical examination was remarkable for a faint apical mid-diastolic murmur. Transthoracic echocardiography (TTE) demonstrated moderate rheumatic mitral valve stenosis with valve area of 1.3 cm 2 by both planimetry and pressure half time. A mass lesion with a broad base was seen attached to the interatrial septum (IAS) inside the left atrium (Fig. 1, Movie 1). Transoesophageal echocardiography (TEE) revealed that the mass (23 x 33 mm) was encapsulated, heterogeneous with cystic degeneration, attached with a broad base to the lower portion of the IAS and extended to the anterior mitral leaflet consistent with left atrial myxoma (LAM). The mass was fixed and did not show any independent mobility or sliding through the mitral valve orifice (Fig. 2, Movie 2). Colour Doppler echocardiography showed that the mass was partially vascularized (Fig. 3, Movie 3). Coronary angiography ruled out significant coronary artery disease and uncovered atypical vascularization of the mass from both right and left coronary arteries (Movies 4 and 5). Cardiovascular magnetic resonance imaging was consistent with LAM. The patient was referred for cardiac surgery. The mass was excised, followed by mitral valve replacement due to encroachment on the anterior mitral leaflet. Gross appearance and histology showed typical features of myxoma (Figs. 4 and 5). The discrimination between LAM and atrial thrombi presents a diagnostic challenge in the presence of mitral stenosis. Usually, LAM arises from the IAS at the level of fossa ovalis. Atrial thrombi classically reside in an atrial appendage, but can also form in the LA body.