The timing of blood transfusions after major surgery may significantly impact heart failure and arrhythmia risks for patients with pre-existing heart disease, according to new research presented at the American Heart Association's Scientific Sessions 2025. The Transfusion Trigger after Operations in High Cardiac Risk Patients (TOP) trial investigated whether earlier blood transfusions could better protect cardiac patients from complications following major general or vascular surgery.
Researchers studied more than 1,400 military veterans undergoing major surgery, comparing two transfusion strategies: one providing transfusions when hemoglobin levels dropped below 10 g/dL and another waiting until levels fell below 7 g/dL. Hemoglobin, the vital component of red blood cells that transports oxygen throughout the body, was monitored after surgery and following each transfusion until discharge or 30 days post-operation.
The analysis revealed that severe complication rates—including death, heart attack, kidney failure, need for heart procedures, or stroke—were nearly identical between the two groups. However, the study found substantial differences in heart-specific complications. Patients receiving earlier transfusions experienced irregular heart rhythms and heart failure in only 5.9% of cases, compared to 9.9% in the later transfusion group, representing a 41% risk reduction.
Lead author Panos Kougias, M.D., M.Sc., chair of the department of surgery at SUNY Downstate Health Sciences University, explained the significance of these findings. "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," Kougias said. He compared the strategies to fuel management: the earlier transfusion approach is like keeping a car's fuel tank above half full, while the later strategy waits until the low-fuel light comes on.
The study's implications challenge current standard transfusion practices for cardiac patients. While waiting to transfuse remains safe and appropriate for many patients, those with serious underlying heart disease undergoing major surgery may benefit from earlier intervention. The findings suggest that a one-size-fits-all transfusion strategy may not be optimal for all patient populations.
The research was simultaneously published as a full manuscript in the peer-reviewed scientific journal JAMA. The trial was funded by the Veterans Affairs Office of Research and Development and involved participants from 16 Veterans Affairs Medical Centers across the United States enrolled between February 2018 and March 2023. Study participants had an average age of 70 years, with 98% being men and 75% self-identifying as white adults.
Study limitations include the predominantly male participant population, which may limit applicability to women, and the fact that healthcare professionals were aware of which transfusion strategy patients received, potentially influencing care decisions. The number of severe complications was also fewer than expected, meaning small differences between groups might have gone undetected.
These findings come at a critical time as healthcare systems seek to optimize surgical outcomes for high-risk patients. The research provides evidence that tailoring transfusion strategies to specific patient populations could improve cardiac outcomes without increasing the risk of severe complications. Additional information about the study is available through the American Heart Association's Scientific Sessions 2025 Online Program Planner.
