Blood loss during or after surgery can place significant stress on people with heart disease, increasing the risk of dangerous complications. Transfusions are often delayed until hemoglobin levels fall very low, yet this approach may leave the heart struggling to compensate for reduced oxygen delivery. A new study that examined whether giving blood earlier, at higher hemoglobin thresholds, could reduce harm found fewer cardiac complications but no difference in the most severe outcomes.

This investigation was led by SUNY Downstate Health Sciences University (Brooklyn, New York, USA) as part of the larger Transfusion Trigger after Operations in High Cardiac Risk Patients (TOP) trial. The study enrolled more than 1,400 military veterans undergoing major general or vascular surgery. Hemoglobin was measured after surgery and reassessed each time blood was given. Participants were followed until hospital discharge or for 30 days, with the final outcome comparisons made at 90 days.

Researchers compared two strategies: an earlier or “liberal” transfusion given when hemoglobin dropped below 10 g/dL, and a later or “restrictive” transfusion given only when hemoglobin fell below 7 g/dL. The trial evaluated major complications such as death, heart attack, kidney failure, stroke, or need for coronary intervention, as well as other clinically important outcomes, including infection, pneumonia, sepsis, arrhythmias, and heart failure.

The study found that earlier transfusion did not reduce the most severe outcomes, with major complication rates nearly identical between groups. However, heart-related complications differed substantially. Patients receiving earlier transfusion had a 5.9% rate of irregular heart rhythms or heart failure compared with 9.9% among those transfused later. This represented a 41% lower risk, indicating that persistent anemia may impose more cardiac stress than the volume of a transfusion.

These results, presented at the American Heart Association Scientific Sessions 2025 and published in JAMA, highlight the need for individualized transfusion decisions. While delaying transfusion remains safe for many patients, earlier intervention may benefit those with serious underlying cardiac disease undergoing major operations. Further research is required to confirm whether early transfusion should become standard in this high-risk subgroup and to refine hemoglobin thresholds tailored to cardiac function.

“Our findings suggest that persistent blood loss in patients with serious underlying heart issues does not increase the risk of serious complications, such as death, heart attack, kidney failure, need for a heart procedure or stroke. However, it might place a greater strain on the heart than the volume from a transfusion, leading to problems like heart failure and irregular heartbeat,” said lead author Panos Kougias, M.D., M.Sc. “The earlier blood transfusion strategy may protect the heart from the effects of blood loss. It’s like keeping a car’s fuel tank above half full, while the transfusion-later strategy is like adding fuel only when the low-fuel light comes on.”

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