Background: The implementation of the VA’s Maintaining Internal Systems and Strengthening Integrated Outside Networks (MISSION) Act in June of 2019 greatly expanded opportunities for Veterans to be referred outside of the Veterans Health Administration (VHA) for complex cardiac procedures and surgeries. However, the VA has been a longstanding national leader in both interventional cardiology and cardiac surgical quality of care. Hence, increased referrals outside of the VHA may reduce the probability that Veterans undergoing cardiac procedures receive the highest care quality and the best procedural outcomes. Significance/Impact: With increasing numbers of Veterans now eligible under the MISSION Act to obtain major cardiac procedures outside VA, it is critically important for Veterans, their VA providers, and VA operational leaders to fully understand the consequences of Veterans' choices in terms of their access to care, quality of care, outcomes of care, and health care costs. The total costs of VA's Community Care program are substantial; it is therefore essential that VA maximizes the value from funds expended on Community Care. Innovation: The proposed research will extend prior studies comparing VA and Community Care provision of major cardiac procedures with a specific focus on the impact of the MISSION Act, which has the potential to vastly expand the number of Veterans receiving care outside VA. Our research will provide novel insight into how Veterans’ choices between VA and non-VA providers could be better informed by information about health care quality and outcomes of care, thus enhancing the decision-making process. Our cost analysis will identify potential opportunities where better care coordination between VA and non-VA providers could improve both the value of care delivered by eliminating gaps in, and reducing duplication of, services. Specific Aims: The primary objectives of this study are to: (a) quantify the changes in use of VA and non-VA cardiac surgery and interventional cardiology services resulting from the MISSION Act, with a focus on how access to care was affected; (b) measure the effects of MISSION Act implementation on the rates Veterans obtain cardiac surgery and interventional cardiology care from high-quality hospitals, and compare the risk- adjusted post-procedure outcomes among Veterans obtaining cardiac procedures in VA hospitals or via Community Care after the MISSION Act was implemented; (c) assess the effect of MISSION Act imple- mentation on the cost of interventional cardiology and cardiac surgical care to both the VA and to Veterans. Methodology: This study will leverage our research team’s substantial expertise with both VA and non-VA clinical, administrative, and cost datasets. We will combine data from VA’s cardiac surgery and interventional cardiology national registries with health care utilization, cost, and outcomes data housed in the VA’s Corporate Data Warehouse, as well as VA’s Community Care...