patient has paroxysmal, persistent or permanent non-valvular atrial fibrillation (af)

eligible for long term warfarin

chads score >= 1 (congestive heart failure [chf], history of high blood pressure, 75 years of age or older, diabetes, prior stroke or transient ischemic attack [tia])

contraindicated for warfarin

contraindicated for aspirin or clopidogrel (plavix)

chf class 4

implanted mechanical valve

atrial septal or patent foramen ovale (pfo) device

platelets < 100,000 or hemoglobin < 10

left ventricular ejection fraction (lvef) < 30%