Effect of Perioperative Blood Transfusion in Anemic Patients Undergoing Infrainguinal Bypass

Abstract

Patients who present with lower extremity ischemia are frequently anemic, and the optimal transfusion threshold for this cohort has remained controversial. We sought to evaluate the effect of blood transfusion on major adverse cardiac events (MACE), including myocardial infarction, dysrhythmia, stroke, congestive heart failure, and 30-day mortality for these patients. All consecutive patients who had undergone infrainguinal bypass at our institution from 2011 to 2020 were included. The primary outcome was MACE, and blood transfusion was the primary exposure. Univariate and multivariable analyses were performed to assess the effects of patient and procedural variables, including red blood cell transfusion, stratified by hemoglobin (Hb) nadir (<7, 7-8, >8 g/dL). Of the 287 patients reviewed for analysis, 146 (50.9%) had required transfusion (mean, 1.6 ± 3 U). The patients who had received a transfusion had had a mean nadir Hb of 8.3 ± 1.0 g/dL compared with 10.1 ± 1.7 g/dL for those without transfusion. The overall incidence of MACE was 15.7% (45 of 287 patients). Univariate analysis demonstrated that MACE was associated with blood transfusion (P = .009), lower Hb nadir (P = .02), higher blood loss (P = .003), higher baseline creatinine (P = .02), previous coronary revascularization (P = .002), nonambulatory status (P = .03), American Society of Anesthesiologists classification 4 or 5 (P < .0001), and preoperative P2Y12 antagonist therapy (P = .049). Transfusion was independently associated with MACE for patients with a Hb nadir >8 (odds ratio [OR], 3.09; P = .006) but not for patients with a Hb nadir of 7 to 8 (OR, 0.818; P = .77). The effect in the Hb nadir <7 group was inconclusive (Fig). The only other variables independently associated with MACE were previous coronary revascularization (OR, 2.58; P = .01) and higher blood loss (OR, 1.05; P = .02). The hospital length of stay for patients with MACE was significantly longer than that for patients without MACE (14.8 vs 8.2 days; P < .001). For patients undergoing infrainguinal bypass, receiving a transfusion with a Hb nadir >8 was associated with a threefold increase in MACE, with a length of stay twice as long. For patients with a Hb of 7 to 8, transfusion did not increase or reduce the incidence of MACE. These findings suggest no benefit of blood transfusions for patients with a Hb nadir >7 and harm for those with a Hb nadir >8.