Cardiopulmonary exercise testing (CPET) is considered to be a gold standard in pre-operative risk assessment and stratification of high risk patients scheduled for major surgery. Surprisingly, only a limited number of studies examined the prognostic role of CPET in cardiothoracic surgery. This is in contrast with rather poor discriminating quality of cardiovascular surgery risk scores and predominantly elderly cardiovascular surgery patients, with significant comorbidity and high degree of frailty. Recently, CPET was shown feasible in coronary artery bypass grafting surgery candidates. Additionally, the rest parameter, which is the partial pressure of end-tidal carbon dioxide (PETCO2) and a submaximal exercise parameter (the VE/VCO2 slope) with good prognostic utility across multiple respiratory exchange ratio values), has been shown to predict mortality and post-operative complications. Whether these rest and submaximal exercise parameters can be used to predict postoperative complications in cardiovascular surgery patients is yet to be determined.