The use of perioperative blood transfusions in coronary artery bypass grafting has decreased considerably over the past two decades. These are the results of a new study conducted by scientists at the University of Iceland and Landspitali – University Hospital, published in the Journal of Cardiothoracic Surgery. This is a positive development since blood transfusions are linked to a higher risk of postoperative complications and thirty-day mortality, and increased healthcare costs.
Coronary surgery is a treatment option for complex coronary artery disease, and perioperative bleeding is one of the most common challenges of the surgery that often calls for blood transfusion. Several factors contribute to the high risk of bleeding in coronary artery surgeries, including the use of cardiopulmonary bypass. Heparin, an anticoagulant, is used to prevent blood clotting in the machine. Additionally, antiplatelet medications are often given before surgery to keep the coronary arteries open.
There are three types of blood transfusions: red blood cells, fresh-frozen plasma and platelets, and these components are either administered separately or in combination. The number of blood components was obtained from the Icelandic Blood Bank. A considerable amount of blood components in Iceland is used for surgeries, especially cardiac surgery. Even though blood components are often lifesaving, they’re expensive, and transfusion costs are high, especially for platelets. Moreover, blood transfusions are linked to an increased risk of postoperative complications, and some patients experience allergic reactions. Therefore, careful use of these transfusion components is important, and studies have shown that following international clinical guidelines can help administer them more effectively. Nonetheless, it is a fact that blood transfusion in coronary artery bypass grafting varies widely between institutions, ranging from 10-100% for red blood cells, 0-90% for platelets and 0-100% for fresh-frozen plasma.
The research, entitled “Reduced risk of perioperative blood transfusions in coronary surgery: A nationwide study over 18 years,” involved 1,850 coronary artery surgeries at Landspitali – University Hospital between 2005 and 2022. The patients’ average age was 67 years and 84% were male. Patients who needed blood transfusions were on average about 4 years older, were assessed as being at higher risk before surgery according to the risk evaluation tool EuroSCORE II, and more frequently used the antiplatelet medication clopidogrel before the surgery. Proportionally, more female patients needed blood components than those who didn’t. Patient records were obtained from medical files and the Icelandic Blood Bank's central database.
It emerged that 64% of patients who underwent coronary artery bypass surgery during the 18-year study period received some type of blood component, most commonly red blood cells (59%), while 30% received plasma, 21% platelets, and 26% received all three components combined. Blood transfusions decreased from 75% during the first 6-year period of the study to 48% in the last period, mainly due to reduced use of red blood cells and plasma. This is also reflected in a 50% reduction in bleeding in the first 24 hours after surgery over the same study periods (from 790 ml to 470 ml), despite many more patients taking antiplatelet medications before surgery, such as aspirin and clopidogrel. Relative use of these medications increased from 38% to 81% and from 3% to 11%, respectively, over the study period. The use of the coagulation factor fibrinogen also increased significantly, from 3% to 29%. Among predictors for blood transfusions were advanced age, female sex and the use of clopidogrel before surgery, whereas aspirin use until surgery was not associated with transfusion.
Almost two in every three patients at Landspitali have received perioperative blood transfusions, which is relatively high, but comparable to many other international studies on the same topic. Proportionally, blood transfusions have decreased, which may be attributed to increased adherence to clinical transfusion guidelines at Landspitali, along with the implementation of patient blood management in the operating theatre, including perioperative use of heparin titration, viscoelastic testing, and cell salvage.
Matthildur María Magnúsdóttir, a 5th-year medical student at the University of Iceland, is the first author of the paper. She has worked on the research along with her studies for the past 3 years. The project was conducted at the Landspitali’s Department of Cardiothoracic Surgery, and Tómas Guðbjartsson, a cardiothoracic surgeon and professor in the Faculty of Medicine at UI, led the research and served as Matthildur’s supervisor.
