Positron Emission Tomography (PET) Imaging of Thrombosis

History of atrial fibrillation or paroxysmal atrial fibrillation;

Retrospective enrollment: TEE to evaluate LAA within the last 14 days, provided the anticoagulation regimen the patient is on is not changed after the TEE. If a patient has a negative TEE and continues the same stable anti-coagulation regimen he/she is on, then it is extremely unlikely that a new thrombus will develop in the left atrial appendage within the next two weeks. Likewise, if a patient not taking any anti-coagulation has a thrombus in the left atrial appendage, then it is extremely unlikely that this thrombus will resolve spontaneously in the next 14 days if the patient continues not to take any anticoagulation. If the TEE leads to a change being made in the anticoagulation regimen (started/stopped/dose modified), then a time window of 72 hours from the TEE to PET imaging will be used. This scheme will ensure that the TEE can serve as an accurate gold standard;

Prospective enrollment: TEE to evaluate LAA scheduled in upcoming 14 days;

Positive test for SARS-CoV-2 RNA detected by RT-PCR collected from the upper or lower respiratory tract analyzed by a certified lab with an FDA approved assay within the last month;