Large left atrial thrombus formation despite warfarin therapy after device closure of a patent foramen ovale

Appropriate anticoagulation after transcatheter device placement is controversial. Patients with no history of thromboembolism or neurologic event typically receive antiplatelet therapy for several months while the device endothelializes. For patients with a history of stroke, there are no established guidelines for postdevice anticoagulation. Most patients receive warfarin, antiplatelet therapy, or a combination. Thrombus formation after transcatheter device placement has been reported for most commercially available devices. We describe a patient who developed a left atrial thrombus after closure of a patent foramen ovale with a CardioSEAL device. The patient had a normal hypercoaguable laboratory evaluation prior to device placement. Thrombosis occurred despite warfarin therapy before and after device placement. The patient's international normalized ratio was checked every 2 weeks after device placement and ranged between 2.0 and 2.8. She had no clinical arrhythmia during this time period. The left atrial thrombus was detected on routine follow-up transthoracic echocardiogram performed 6 months after device deployment. A subsequent transesophageal echocardiogram demonstrated no residual shunt, appropriate positioning of the device, flat against the septum, and a 1 x 2 cm thrombus attached to the superior and posterior left atrial arm near the junction with the native septum. A fluoroscopic image demonstrated no arm fractures. The device and thrombus were subsequently removed at surgery without complication. This case is perplexing in that the patient received appropriate anticoagulation had a negative hypercoaguable work-up, no residual shunt, and a well-positioned device.