The purpose of this research is to gather information about the effectiveness and safety of Left Atrial Appendage Occlusion (LAAO) device procedures in patients using a Watchman device performed on days where doctors perform a large number of procedures.

The study primary outcome is to evaluate complications during the procedure up to 30 days after the procedure.

The final outcome is to determine successful placement within 31 - 90 days after implant.

This is a phase 2 study for patients that have been diagnosed with recurrent glioblastoma, a type of brain cancer. This study is testing an investigational combination of two drugs, reltalimab and nivolumab."Investigational" means it has not been approved by the United States Food and Drug Administration (FDA). The main purpose of this study is to see if there is a difference in overall survival rate in patients who receive a combination of retatlimab and nivolumab versus those who receive the standard of care treatment, lomustine, in patients with recurrent brain cancer. Participants in this study can expect to be in this study for up to five years from the day study participation starts. Subjects with investigational project being given on day 1 of each cycle, a cycle being 28 days. Cycles will continue until disease gets worse or study doctor decides it is in the subject's best interest to stop. Study will be divided into group 1 and 2. Group 1 will receive investigational drugs and group 2 will receive the standard of care. A computer will be used to assign groups in a process called randomization. Much like a toss of a coin, subjects will have equal opportunity to randomized to either group 1 or 2.