In many hospitals, patients undergoing cardiac surgery receive a higher amount of blood products transfusions compared to other disciplines. Blood transfusion comes with risks and drawbacks, such as increased morbidity and mortality across different patient groups, and specifically patients undergoing cardiac surgery, and high costs. Patient Blood Management (PBM) practices focus on the application of evidence based medical and surgical concepts in order to preserve the patient’s own blood. Unfortunately, studies suggest that only a small fraction of published guidelines are implemented and followed into daily clinical practicedue to clear guidance, concerns about risks, and lack of knowledge, interdisciplinary commitment or resources. The widespread adoption of electronic health record (EHR) offers the opportunity to improve clinical outcomes through use of decision support system to guide the healthcare providers through best practices and guidelines. Decision support systems can be active, data-based, patient-specific and act timely, and can be more useful that adding new clinical practice guidelines. This case study quantifies the quality of the data registration and provides the results for adherence to perioperative PBM guidelines for coronary artery bypass grafting (CABG) procedures during a three-year period (2018 to 2020), in the St. Antonius hospital, a single heart center that performs over 10% of the total number of heart operations in the Netherlands. With this case study we identify some of the possible improvement factors for PBM in our center. We also quantify the impact of the quality of the registration in the EHR on the analysis results and on possible implementation of decision support systems.