Mitral stenosis and pedunculated left atrial thrombus: an unusual presentation

A 32-year-old patient who was 32 weeks pregnant presented with New York Heart Association Class III dyspnoea to a maternity clinic. Transthoracic echocardiography revealed features of severe pliable mitral stenosis and pulmonary hypertension. A mass detected in the left atrium was presumed to be a thrombus. The patient was treated with a β-blocker, loop diuretic, and low-molecular-weight heparin, and subsequently underwent successful unassisted vaginal delivery at term. One month postpartum, the left atrial mass appeared unchanged despite adequate anticoagulation. Transoesophageal echocardiography (TOE) was performed as a prelude to mitral valve surgery. Two-dimensional TOE not only confirmed severe pliable mitral stenosis but also showed a mass of mixed echogenicity in the left atrium that appeared to be unattached (Panel A; see Supplementary data online, Video S1). However, three-dimensional (3D) TOE from the left atrial perspective revealed a mass attached to the interatrial septum via a stalk and offered an accurate assessment of the mitral valve area (Panels B–D; see Supplementary data online, Video S2). In view of the 3D-TOE findings, a provisional diagnosis of left atrial myxoma was made and the patient referred for surgery. Using a left atrial approach, she underwent open mitral commissurotomy and resection of the left atrial mass (Panel E), which was thought to be suggestive of a myxoma. Comprehensive histology confirmed a thrombus adherent to the endothelium, which, under traction, resembled a stalk. This case illustrates that echocardiographic signs suggestive of differentiating a myxoma from a thrombus are non-diagnostic. Supplementary data are available at European Heart Journal – Cardiovascular Imaging online.