Anemia and postoperative outcomes after open and endovascular repair of intact abdominal aortic aneurysms

Objective: Anemia is associated with increased cardiac adverse events during the early postoperative period because of high physiologic stress and increased cardiac demand. The aim of this study was to assess the surgical outcomes and prognostic implications of anemia in patients undergoing repair of intact abdominal aortic aneurysms (AAAs). Methods: A retrospective analysis of all patients who underwent open aortic repair (OAR) or endovascular aneurysm repair (EVAR) in the Vascular Quality Initiative database (2008-2017) was performed. Patients with preoperative polycythemia, patients with ruptured aneurysms, and patients transfused with >4 units of packed red blood cells were excluded. Hemoglobin levels were categorized into three groups: moderate-severe anemia (<10 g/dL), mild anemia (10-12 g/dL in women and 10-13 g/dL in men), and no anemia (>12 g/dL in women and >13 g/dL in men). Multivariate logistic models and coarsened exact matching were used to analyze the association between anemia and 30-day mortality and between anemia and major in-hospital complications after OAR and EVAR. Results: A total of 34,397 patients were identified undergoing AAA repair. Of those, 28.5% had mild anemia and 4.3% had moderate-severe anemia. In both OAR (n = 6112) and EVAR (n = 28,285), patients with moderate-severe anemia had significantly higher rates of in-hospital adverse events, such as in-hospital mortality, myocardial infarction, renal and respiratory complications, and reoperation, compared with patients with mild or no anemia. They also had higher rates of 30-day mortality. After multivariate analysis and 1: 1 coarsened exact matching, no association was found between anemia and 30-day mortality and other in-hospital outcomes in patients undergoing OAR. On the other hand, in EVAR, moderate-severe anemia was associated with 2.7 times the odds of 30-day mortality (odds ratio [OR], 2.65; 95% confidence interval [CI], 1.69-4.18), 2.5 times the odds of renal complications (OR, 2.47; 95% CI, 1.78-3.43; P<.05), and twice the risk of acute congestive heart failure (OR, 1.96; 95% CI, 1.18-3.25) and respiratory complications (OR, 2.01; 95% CI, 1.26-3.19). Mild anemia was also associated with increased odds of 30-day mortality and renal and respiratory complications in patients undergoing EVAR. Interestingly, preoperative blood transfusion in mildly anemic patients undergoing EVAR was associated with double the odds of in-hospital major adverse cardiac events (stroke, death, and myocardial infarction; OR, 2.1; 95% CI, 1.38-3.11; P<.001). Conclusions: Preoperative anemia is associated with higher odds of 30-day mortality and in-hospital adverse outcomes after EVAR but not after OAR. These findings highlight the need to incorporate anemia into the preoperative risk assessment of patients undergoing EVAR. Future studies are needed to assess the efficacy of medical therapies in improving postoperative outcomes in anemic patients undergoing AAA repair.