Association Between Postoperative Nadir Hematocrit and Mortality Within 28 Days After Coronary Artery Bypass Grafting: A Retrospective Cohort Study Based on the MIMIC-IV Database

This retrospective cohort study examined the relationship between postoperative nadir hematocrit (nHCT) levels and 28-day mortality following coronary artery bypass grafting (CABG) using data from the MIMIC-IV database. The study included adults who underwent CABG during an ICU stay, excluding those with missing postoperative hematocrit or 28-day vital status. Results showed that lower nHCT was significantly associated with higher 28-day mortality and adverse secondary outcomes such as acute kidney injury and postoperative delirium. Specifically, nHCT levels between 27% and 31% were linked to the lowest mortality risk, with an inflection point at 27% where survival benefits plateaued. These findings underscore the importance of monitoring postoperative nHCT and could guide future blood management strategies in CABG patients.