Study population
This was a single centre study at Rigshospitalet, Denmark. 356 patients planned to undergo coronary artery by-pass grafting and/or aortic valve replacement were enrolled from February 2016 to March 2018. A subgroup of 50 patients, consecutively enrolled from October 2017 to January 2018, were used for the reproducibility studies. In order to reflect daily clinical practice, patients were not excluded due to poor acoustic window, dyspnoea, or obesity. The study was performed in accordance with the Declaration of Helsinki and approved by the Ethics Committee for the Capital Region Copenhagen. All patients provided written informed consent.