Liberal Transfusion Strategy for Acute MI and Anemia Doesn’t Impact QoL

A more liberal transfusion strategy for patients with acute MI and anemia does not improve quality of life when compared with a more restrictive approach, according to an analysis of the MINT trial.

There was a suggestion that the liberal strategy—with a goal to keep hemoglobin levels above 10 g/dL—improved quality of life in patients with type 1 MI and those with heart failure (HF) at baseline, but those results should be considered hypothesis-generating, say investigators.

“I would still recommend a liberal transfusion strategy,” lead investigator Micah Prochaska, MD (University of Chicago, IL), told TCTMD. “It doesn’t harm quality of life, but if your rationale is, ‘I’m going in there to improve their quality of life,’ then, at least overall, we didn’t see an effect.”

Based on the primary MINT results, a liberal red blood cell transfusion strategy in acute MI patients with anemia is considered reasonable in the latest ACS guidelines (class 2b, level of evidence B). The international trial included 3,504 acute MI patients with hemoglobin levels less than 10 g/dL and randomized them to a restrictive strategy that used a hemoglobin cutoff of 7-8 g/dL before transfusions were permitted or the more liberal approach.

The study missed its primary endpoint but strongly hinted at a benefit with a liberal transfusion strategy. All-cause mortality or MI at 30 days occurred in 16.9% of those randomized to the restrictive strategy and 14.5% in the liberal group, just missing statistical significance (RR 1.15; 95% CI 0.99-1.34). Cardiac mortality occurred in 5.2% and 3.2% of patients in the restrictive and liberal groups, respectively (RR 1.74; 95% CI 1.26-2.40). 

The underlying hypothesis behind the prespecified secondary analysis, which was presented at the International Society of Blood Transfusion congress in Milan, Italy, this week and published simultaneously online in JAMA Internal Medicine, was that increasing oxygen delivery to the heart and skeletal muscle would reduce symptoms of anemia such as fatigue and shortness of breath. This, in turn, would lead to better functional status and quality of life. 

“Sometimes the reason why we give people blood is to make them feel better,” said Prochaska. “My thought was this would likely work. When you have reduced oxygen delivery to the myocardium and skeletal tissues, that’s what produces symptoms of anemia. What’s interesting about MINT is that we know myocardial infarction [also leads to] a reduction in quality of life.”

Subgroup Benefits Make Sense

The new analysis focused on 2,844 patients (mean age 71.9 years; 54.5% male) with quality-of-life data at 30 days. Overall, there was no difference between the two transfusion strategies in mean or median scores on the EQ-5D-5L, a validated tool that tracks quality of life across five domains (usual activities, anxiety/depression, mobility, pain/discomfort, and self-care). There also was no difference in the index score that tracks overall health status or in self-reported health using a visual analog scale (Health Today).

Patients with type 1 MI tended to have better quality-of-life scores around usual activities, mobility, and self-care, as well as a higher overall index score, when treated with a liberal transfusion approach than type 1 MI patients randomized to the restrictive strategy. This difference was not observed in patients with type 2 MI. Patients with HF also had trends toward better quality-of-scores across several domains, and a significant improvement in the Health Today score, with the liberal strategy.

While the subgroup analysis is hypothesis-generating, Prochaska noted that in patients with type 1 MI, those randomized to the liberal transfusion strategy saw plausible improvements in several domains.

“Anxiety/depression and mobility are correlated sometimes, but they’re really different domains,” he said. “You get into this [situation] where you’re measuring [quality of life] globally and it’s hard to find a signal. The analogy would be if someone breaks their leg. The surgeon fixes their leg and you measure an improvement in their ability to walk. I would believe that, but if you didn’t see an improvement in their depression, does that mean fixing their leg didn’t work? No, it means the depression was due to other things.”      

Prochaska suspects a larger study might have shown an improvement in quality of life, but he said that even without it, the overall trial supports the use of liberal red blood cell transfusion in acute MI patients with anemia.

“Quality of life is so difficult to measure and the confidence intervals around any sort of quality-of-life measurement are so wide that you need massive amounts of people in a trial to detect a clinically significant effect,” he said. “The counterargument is that’s because there was no effect, but one of the reasons why we saw an effect [on the primary endpoint in MINT] is because it was the biggest, most comprehensive study done. It’s even still possible that it’s not big enough to detect quality-of-life effects.”