Previous research identified a relationship between anesthesia handoffs and rates of major complications and mortality compared to patients who had the same anesthesiologist throughout their procedure. This retrospective cohort study including over 102,000 patients in Ontario, Canada, explored this relationship among patients undergoing cardiac surgery. Analyses revealed that anesthesia handovers were associated with poorer outcomes (i.e., higher 30-day and one-year mortality rates, longer hospitalizations and intensive care unit stays) compared with patients who had the same anesthesiologist throughout their procedure.