Right Atrial Thrombus after placement of an ASD closure device

This is my mother's case as published (http://eurheartj.oxfordjournals.org/content/early/2011/09/06/eurheartj.ehr313.extract):

"A 65-year-old female patient with a 24 mm atrial septal secundum defect underwent successful percutaneous closure of the defect 10 years earlier using a 38 mm StarFlex device; NMT Medical, Boston, MA, USA. The patient was undergoing follow-up annually with no abnormal findings at echocardiography or other complications. At her recent  chocardiography evaluation, two-dimensional (2D) study demonstrated a mass 2 × 2 cm (arrows) in the right atrium at the posterior portion of the device. The transoesophageal echocardiography and three-dimensional transthorasic echocardiography (3D) images of the mass are shown in Panels B and C, respectively. A cardiac magnetic resonance imaging followed the echocardiography evaluation (Panel D) and confirmed the diagnosis of the mass within the right atrium, which was consistent with a large thrombus attached to the posterior portion of the closure device. This is the first case reported in the literature of thrombus formation on a closure device 10 years after the intervention, probably due to incomplete endothelialization of the device. This case demonstrated the need for continuous follow-up of patients after device implantation."

What would be the best treatment? She has been on anticoagulants for 3 months now. Any piece of advise would be really appreciated! Is there any research centre/hospital anywhere in the world specialised in thrombi?

Thank you very much for your time!!!