NEW ORLEANS — A new study suggests that the timing of blood transfusions after major surgery may influence the risk of heart failure and irregular heartbeats in patients with underlying heart disease. The research, presented at the American Heart Association’s Scientific Sessions 2025, indicates that an earlier transfusion strategy — when hemoglobin levels drop below 10 g/dL — could reduce these complications compared to the standard practice of waiting until hemoglobin falls below 7 g/dL.
The Transfusion Trigger after Operations in High Cardiac Risk Patients (TOP) trial enrolled 1,424 U.S. military veterans undergoing major general or vascular surgery at 16 Veterans Affairs Medical Centers. Participants, with an average age of 70, were randomized to either a liberal transfusion strategy (transfuse when hemoglobin <10 g/dL) or a restrictive strategy (transfuse when hemoglobin <7 g/dL). The study followed patients for 90 days after surgery.
Severe complications — including death, heart attack, kidney failure, need for a heart procedure, or stroke — occurred at similar rates in both groups: 9.1% in the liberal group versus 10.1% in the restrictive group. However, the incidence of less severe but serious complications such as new irregular heartbeat, cardiac arrest, or heart failure was significantly lower in the liberal transfusion group: 5.9% compared to 9.9% in the restrictive group, representing a 41% relative risk reduction.
“We were surprised that the restrictive transfusion strategy was associated with a higher rate of heart failure,” said lead author Panos Kougias, M.D., M.Sc., chair of the department of surgery at SUNY Downstate Health Sciences University. “The traditional thinking has been that giving more blood may potentially overload the heart and worsen failure. Our finding suggests that in high-risk heart patients, persistent anemia might place a greater strain on the heart than the volume from a transfusion.”
The study, simultaneously published in JAMA, challenges the conventional one-size-fits-all approach to transfusion thresholds. “For some patients, waiting to transfuse remains safe and appropriate,” Kougias noted. “However, for patients with serious underlying heart disease undergoing major surgery, our findings show that an earlier blood transfusion could help prevent serious heart complications.” The TOP trial was funded by the Veterans Affairs Office of Research and Development.
Researchers caution that the study’s limitations include a predominantly male cohort (98%), which may limit generalizability to women. Additionally, healthcare providers were aware of the transfusion strategy, potentially influencing care. The number of severe complications was lower than anticipated, meaning small differences may have gone undetected.
The findings add to the ongoing debate about optimal transfusion practices. For more information, see the full abstract at the American Heart Association’s Scientific Sessions 2025 Online Program Planner. The American Heart Association, a leading source of health information for over a century, continues to fund groundbreaking research to improve cardiovascular care. More details are available at heart.org.
