A 64-year-old Caucasian male who had percutaneous closure of a patent formaen ovale (PFO) presented for follow-up 2 years later.

A shows a transesophageal echocardiogram (TEE) of: 1) a left atrial (LA) mass; 2) the LA mass arising from the atrial septal defect (ASD) closure device; and 3) the protrusion of the mass into the left ventricle (LV). The mass was large and hyper mobile, flopping into the mitral inflow tract consistent with a thrombus versus a myxoma. Surgical excision was indicated given the size, mobility, and danger of embolization. B shows a: 1) 6 × 5.5 × 1.5 cm brownish gelatinous mass; 2) amplatzer device; and 3) the site of attachment to the ASD/PFO closure device. Histopathological analysis confirmed myxoma. C shows TEE at the time of original diagnosis of PFO; no mass was noted in the LA.

This case represents a surprising outcome of a surveillance TEE (Online Video 1) following percutaneous ASD closure. Previous case reports have described myxoma growth rates of up to 2.2 mm/month (1). The growth rate in this case was 2.5 mm/month, suggesting that growth rate alone is not an adequate distinguishing feature for thrombus versus myxoma.