Anemia may help explain why women are more likely to die during heart bypass surgery
Intraoperative anemia during coronary artery bypass grafting (CABG) procedures is much more common among women than men, according to research published in the Journal of the American College of Cardiology.[1] The study’s authors believe this is the primary reason female patients undergoing CABG face an increased risk of death.
“The higher operative mortality after CABG in women has been previously well-described,” wrote first author Lamia Harik, MD, a fellow in cardiothoracic surgery research at Weill Cornell Medicine, and colleagues. “In a recent meta-analysis of 84 observational studies, including nearly 1 million patients, women had significantly higher risk for operative mortality and major adverse cardiac events than men.[2] Despite improvements in CABG outcomes, this sex difference has persisted over time.”
To learn more, Harik et al. tracked data from more than 1.4 million patients who underwent primary isolated CABG from 2011 to 2022. All data came from the Society of Thoracic Surgeons Adult Cardiac Surgery Database. The median patient age was 66 years old, and 24% were women.
Women treated with CABG had a lower median preoperative hematocrit, median estimated preoperative red blood cell volume and median nadir intraoperative hematocrit than men. Life-threatening anemia—defined as a nadir intraoperative hematocrit below 19.5%—was more common among women.
The operative mortality rate, meanwhile, was 2.8% for women and 1.7% for men. Harik and colleagues determined that 38.5% of that increased mortality risk was directly related to intraoperative anemia.
The authors did emphasize that their observational analysis was not necessarily powered to establish causation. However, the association seen in these data do suggest this is an area for researchers to continue studying in the years ahead. The group also noted that intraoperative anemia is a “relatively easy target for interventions aimed at improving CABG mortality in women.”
“Over the years, proposed drivers of the sex disparity in CABG mortality have ranged from anatomic factors (more spastic and smaller coronary arteries in women) to clinical factors (greater age and baseline risk profile in women undergoing CABG) that are either immutable (the former) or very difficult to change (the latter),” they wrote. “Interventions to prevent or lessen severe intraoperative anemia seem comparatively simple to enact. For example, smaller circuits for cardiopulmonary bypass to reduce priming volume, the use of retrograde autologous priming, and the use of autologous blood donation are all relatively simple and low-cost interventions that might be tested in a prospective fashion.”
Michael has more than 18 years of experience as a professional writer and editor. He has written at length about cardiology, radiology, artificial intelligence and other key healthcare topics.