Files in this Data Supplement:

• Movie I - (AVI file) (4.2 MB). Long axis view of the left atrial appendage prior to cardioversion showing mild spontaneous echo contrast without evidence thrombus. Recommended application for viewing: Windows Media Player.
• Movie II - (AVI file) (8.7 MB). Long axis view of the left atrial appendage immediately following electrical cardioversion showing mild dilatation of the left atrial appendage with severe spontaneous echo contrast and a newly formed distinct mobile mass (thrombus) in the body and apex of the LAA throughout the cardiac cycle, consistent severe LAA stunning. Recommended application for viewing: Windows Media Player.