Unexpected impact of preoperative anemia in low-risk isolated coronary artery bypass grafting or single-valve surgical patients: Do not overlook these patients in anemia management

Preoperative anemia is prevalent in cardiac surgery and independently associated with increased risk for short-term and long-term mortality. The purpose of this study was to examine the effect of preoperative hematocrit (Hct) on outcomes in cardiac surgical patients and whether the effect is comparable across levels of Society of Thoracic Surgeons Predicted Risk of Mortality (STS PROM). The study consisted of adult, isolated coronary artery bypass grafting (CABG) or single-valve surgical patients in a statewide registry from 2011 to 2022 (N = 29,828). Regressions were used to assess effect of preoperative Hct on STS-defined major morbidity/mortality including the interaction of Hct and STS PROM as continuous variables. Median age was 66 years (58-73 years), STS PROM was 1.02% (0.58%-1.99%), and preoperative Hct was 39.5% (35.8%-42.8%). The sample consisted of 78% isolated CABG (n = 23,261), 10% isolated mitral valve repair/replacement (n = 3119), 12% isolated aortic valve replacement (n = 3448), and 29% were female (n = 8646). Multivariable analyses found that greater Hct was associated with reduced risk of STS-defined morbidity/mortality (odds ratio, 0.96; P