Data required for registry participation are collected retrospectively from existing medical records or concurrently in the normal course of treatment. The Societal Document and safety recommendations for left atrial appendage occlusion recommend additional testing and contact with the patient outside the hospital episode of care at 45 days, 6 months, 1 year and 2 years post-procedure. All registry data (in-hospital and follow-up) is captured by participating sites using an electronic data collection tool provided by the LAAO Registry or in the future the option will be available for collecting data using a certified software application that has been reviewed and certified as compliant with the transmissions specifications established by the ACC for the LAAO Registry.