You probably know the feeling of running out of breath faster than you used to.
For older adults living with heart failure, that breathlessness can make even a short walk feel like a hill. A quiet shortage of one mineral may be part of the reason.
A single intravenous dose of iron improved exercise capacity by about 10 percent in patients with the most common form of heart failure. Researchers at Mass General Brigham and Harvard Medical School reported the finding in Circulation.
The trial enrolled 65 adults with heart failure with preserved ejection fraction, a form in which the heart muscle has stiffened but still pumps. All of them were also low on iron.
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What the Harvard team actually measured
Participants received one 1,000-milligram infusion of ferric derisomaltose, an intravenous iron drug sold as Monoferric.
Their peak oxygen uptake rose by about 1.2 milliliters per kilogram per minute at twelve weeks.
Those who got a placebo infusion showed essentially no change. Peak oxygen uptake is a standard measure of exercise capacity in cardiology, tracking how much oxygen the body can use at maximum effort.
On other measures the pattern held. Walking distance in a six-minute test improved more in the iron group than in the placebo group.
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The New York Heart Association symptom class, a standard rating of how much daily life is limited by heart failure, also improved after the infusion. Patient-reported quality-of-life scores, however, showed no significant difference between the two groups.
"The improvement we observed in peak VO2 represents a clinically meaningful increment for patients with heart failure," said Rajeev Malhotra, associate professor of medicine at Harvard Medical School.
The comments came in a statement from Mass General Brigham.
Why so many patients with heart failure run short on iron
Iron deficiency is common in heart failure and often missed. Broader research suggests it affects between 37 and 75 percent of heart failure patients, depending on the setting and the cutoff used.
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In this trial, iron deficiency was defined as a ferritin level below 100 nanograms per milliliter, or below 300 with low transferrin saturation.
Despite how common it is, few patients are screened for it.
One review of a large urban hospital system found that fewer than two percent of patients admitted for heart failure had their iron levels checked. Fatigue and breathlessness overlap with symptoms of heart failure itself.
What the study does not settle
The trial was small. Only 65 people took part, the median age was 68, 72 percent were women, and almost all were white.
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The authors say the results need to be confirmed in larger and more diverse groups, and over follow-up longer than twelve weeks.
No serious adverse events were reported in the iron group during the trial. The infusion was given once, in a clinic, over roughly a quarter of an hour.
Patients with heart failure who want to know their status can ask their cardiologist for an iron panel, which checks ferritin and transferrin saturation from a routine blood draw.
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This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.