High-dose IV iron reduces rate of MI in patients undergoing hemodialysis
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Among patients undergoing maintenance hemodialysis, high-dose IV iron reduced the rate of fatal or nonfatal MIs over 2 years compared with lower-dose iron, according to an analysis of the PIVOTAL trial published in Cardiovascular Research.
The PIVOTAL trial
In the PIVOTAL trial, patients undergoing hemodialysis with ferritin concentration less than 400 µg/L and a transferrin saturation less than 30% were randomly assigned to high-dose or low-dose IV iron.
As Healio previously reported, use of higher-dose IV iron in patients undergoing hemodialysis reduced erythropoiesis-stimulating agent dose requirements and did not increase toxicity, mortality or the incidence of nonfatal CV events.
“Concerns have been expressed that intravenous (IV) iron could increase the prevalence or severity of coronary artery disease, and even increase coronary artery events,” Mark C. Petrie, professor of cardiology at the Institute of Cardiovascular and Medical Sciences at the University of Glasgow, and colleagues wrote. “These concerns have emerged from observational studies in humans, animal studies and small mechanistic studies. Others have suggested that IV iron may not increase coronary events, but there are no data to suggest that IV iron might reduce MIs.”
PIVOTAL subanalysis
In this prespecified analysis, researchers evaluated the association between secondary endpoints of the PIVOTAL randomized trial, including fatal or nonfatal MI and IV iron supplementation at high compared with low doses.
During a median follow-up of 2.1 years, 8.4% of PIVOTAL participants experienced a MI, most of which occurred in older patients (P < .001). The rate of death after nonfatal MI at 1 year was 40% among patients undergoing hemodialysis and receiving IV iron and increased to 60% at 2 years.
Researchers observed a more than twofold greater rate of fatal and nonfatal type 1 MIs than fatal and nonfatal type 2 MIs (3.3 vs. 1.3 per 100 patient-years), and a sixfold greater rate of nonfatal non-STEMIs than fatal and nonfatal STEMIs (3.3 vs. 0.5 per 100 patient-years).
Overall, MI was the cause of 5% of all-cause deaths in the cohort.
Following a time-to-first event analysis, researchers observed that fatal or nonfatal MIs occurred in fewer participants in the high-dose IV iron group compared with the low-dose group (7.1% vs. 9.7%; HR = 0.69, 95% CI, 0.52-0.93; P = .01), as did nonfatal MIs alone (HR = 0.69; 95% CI, 0.51-0.93; P = .01).
According to the study, fatal or nonfatal type 1 MI occurred in 5.7% in the high-dose IV iron group compared with 7.6% of the low-dose group (HR = 0.71; 95% CI, 0.51-0.99; P = .04).
After an analysis isolated to recurrent events, researchers observed that only fatal and nonfatal type 1 non-STEMIs were reduced by high-dose IV iron compared with low-dose (HR = 0.71; 95% CI, 0.51-1; P = .05)
“In patients who had started hemodialysis less than 12 months prior to enrollment, MI was a common event, with 8% having a fatal or nonfatal MI over 2 years of follow-up,” the researchers wrote. “IV iron administered in a high-dose regimen reduced acute fatal and nonfatal MI compared with low-dose iron. High-dose IV iron is the first therapy to reduce MIs in patients undergoing maintenance hemodialysis.”
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