Assessment of Transnational Performance of the Universal Cardiac Surgical Risk Score Across International Sites

ATLAS is a prospective, observational, multicenter cohort study of how accurately the Universal Cardiac Surgical Risk Score (UCSRS) predicts 30-day outcomes after adult cardiac surgery, compared head-to-head with two established models, STS-PROM and EuroSCORE II. Consecutive adult patients undergoing cardiac surgery are enrolled at each participating center over 12 months. All three scores are recorded for each patient. No score is returned to the treating team or influences clinical care. Discrimination and calibration of each score are assessed against 30-day major adverse cardiac and cerebrovascular events (MACCE). The model under evaluation, UCSRS version 3.2, was specified and calibrated against published registry mortality using simulated patients before enrollment. No simulated patient has an outcome, so no performance claim is made before this study.

Inclusion Criteria: * Age 18 years or older * Undergoing cardiac surgery at a participating institution during its enrollment period (isolated CABG, isolated valve, combined CABG and valve, multiple valve, aortic surgery, redo sternotomy, or other adult cardiac surgical procedures, on- or off-pump) * Enrolled consecutively, without selection Exclusion Criteria: * Age under 18 years * Congenital heart surgery performed under a pediatric program * Heart transplantation or ventricular assist device implantation as the primary procedure * Cases in which the comparator scores cannot be computed from available pre-operative data