This study will be a non-blinded observational study with a control group. Subjects will be recruited from the patient pool of the Principal Investigator and Co-Investigators. All subjects in the intervention group will have had the WATCHMAN device implanted at UPMC. The control group in this trial will be comprised of age-matched controls from the control group in the WATCHMAN device trial, also from the patient pool of the Principal Investigator and Co-Investigators. Subjects will be approached by one of the Investigators.