Accordingly, given the uncer- tainties and relatively low risk of initial stroke caused by PFO or ASA and the potential risk of antithrombotic therapy or invasive treatments, no treatment is recommended for the pri- mary prevention of stroke in people with PFO orASA. Several studies have examined the treatment of PFO with antithrom- botic therapy or percutaneous closure devices in patients with cryptogenic stroke, but a discussion of secondary prevention exceeds the scope of this document.482,493 495 Cardiac Tumors Benign primary cardiac tumors such as myxomas, papillary fibroelastomas, and primary malignant cardiac neoplasms such as sarcomas may embolize to the brain and cause isch- Embolic stroke is most likely to occur with intracavitary tumors that have friable surfaces. Myxoma is the most common cardiac tumor, and the majority of them occur in the left atrium.498 About 30% to 40% of myxomas Stroke or TIA is the presenting symptoms in half of the patients with papillary fibroelastomas.500 Surgical exci- sion of atrial myxomas is recommended. 