What is a reasonable management strategy for severely symptomatic atrial fibrillation with persistent LAA thrombus in spite of compliance with several different anticoagulation agents?  

As long as a candidate, would likely need CT surgery to remove LAA/thrombus and MAZE. You could consider Penumbra but that would be high risk and you may also need brain protection. This type of patient would be best discussed and managed in a large hospital with HEART team discussion based on local...