A cohort of all acute ascending aortic dissection repair surgeries will be extracted from the National Adult Cardiac Surgery Audit (NACSA) database. The current dataset version 4.12, available for download from the website of the National Institute for Cardiovascular Outcomes Research (see links), contains 168 fields that detail pre-operative patient characteristics, operative details and post-operative outcomes. The dataset is revised intermittently to meet the requirements of users and to respond to changes in the management of adult cardiac surgery; however, the fields to be analysed in this study have not been subject to any documented revisions. The extracted data are to be cleaned using version 9.9 of the NACSA cleaning algorithm.