Aortic Root Replacement Procedures: A Validation Study of the Western Denmark Heart Registry from 1999 to 2022

<b>Background/Objectives</b>: We reviewed data from the Western Danish Heart Registry (WDHR), which collects mandatory information on heart surgeries in Western Denmark, to validate cases with aortic root replacement (ARR) and assess the validity of registered data for all recorded cases. <b>Methods</b>: Patients registered in the WDHR with Danish Health Care Classification System (SKS) codes KFC and KFM from January 1999 to April 2022 were reviewed using electronic medical records. All patients who underwent ARR were included, and clinical data from the WDHR were adjudicated against electronic medical records. <b>Results</b>: A total of 847 cases with ARR were identified. Missing values averaged 12.0% in baseline variables (range: 3.2-22.1%), 7.3% in EuroSCORE II variables (range: 0.8-48.9%), and 5.5% in postoperative outcome variables (range: 4.1-8.1%). After adjudication, unrecovered data averaged 6.5% for baseline variables (range: 0.1-11.7%), 5.3% for EuroSCORE II variables (range: 0-32.5%), and 0.5% for postoperative outcomes (range: 0-0.8%). Missing data among EuroSCORE II were lower from 2012 and beyond (2.9% (range: 0.6-14.3%)). The median EuroSCORE II according to the WDHR was 6.2% (95% confidence interval 1.4-6.3) and after adjudication 10.7% (95% confidence interval 3.3-13.3). The positive predictive value for arrhythmia, central nervous damage, dialysis, reoperation for bleeding, and reoperation for ischemia exceeded 95%. <b>Conclusions</b>: The WDHR demonstrated overall value for clinical epidemiological research in ARR, but cases require validation to differentiate between procedures due to insufficient coding, while adjudication resulted in significantly higher data completeness for the majority of the variables.