The ADIOS study is a prospective, observational study will evaluate one hundred and thirty (130) patients with non-valvular atrial fibrillation who are currently receiving treatment with apixaban as indicated to reduce the risk of stroke or systemic embolism, and who require an elective major surgical or invasive procedure will be included in the study. The purpose of the study is to evaluate the efficacy of the recommended pre-procedure washout period of 48 hours.