Respiratory filters may reduce endothelial dysfunction and B-type natriuretic peptide (BNP) increases in patients with heart failure (HF) exposed to air pollution, as suggested by results of the FILTER-HF trial suggest, published in JACC: Heart Failure.

Air pollution is a worldwide health hazard, responsible for approximately 3.7 million premature deaths in 2012, as estimated by the World Health Organization. Fine particulate pollutants are most often associated with adverse cardiovascular events. The combustion-derived particulate in diesel exhaust exposure (DE) is a major source, according to background information in the study.

FILTER-HF trial investigators noted that previous studies have focused more on links between air pollution and myocardial infarction, despite air pollution being associated with an increased risk for HF decompensation. Therefore, they tested whether a respiratory filter could reduce endothelial dysfunction, as well as other adverse cardiovascular events related to DE.


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Twenty-six patients with HF and 15 controls were randomly assessed in 3 sessions conducted at least 48 hours apart. They were assigned to a controlled inhalation protocol in each session: clean air obtained from compressed-air breathing, unfiltered pollution obtained from dilute DE, standardized by maintaining the particulate matter (PM) 2.5 concentration at 300 μg/m3, and filtration obtained from DE passed through a mask filter intervention. Endothelial function was measured in 3 stages: baseline, brachial arterial occlusion, and post-occlusion recording of induced reactive hyperemia response (RHi).

A shift in endothelial function served as the primary end point, while secondary end points included arterial stiffness, blood biomarker analysis, changes in exercise testing, and heart rate variability.

RHi decreased by 21% during DE (P=.002, clean air vs DE) in the HF group and improved by 20% during filtration (P=.019, DE vs filter). DE also decreased arterial stiffness in the HF group, compared with clean air (P=.007, clean air vs DE), as well as in the control group (P=.069, clean air vs DE), but there were no differences between filtered and unfiltered DE

DE was also associated with shorter 6-minute walking test distance vs clean air in both groups, but was not improved during filtration. BNP levels increased by 41.5% in the HF group after diesel particulate inhalation (P=.004, clean air vs DE) and during filtration, decreased by 33.8% (P=.015, DE vs filter). 

“To our knowledge this is the first randomized study to show that a simple filter intervention could reduce endothelial dysfunction and BNP increases associated with short-term exposure to DE in patients with HF,” the researchers noted. “Our findings suggest that PM2.5 is the most important cause of endothelial dysfunction associated with air pollution exposure.”

Given the results, this trial could provide a new strategy for treatment and prevention of pollution-related HF morbidities. Researchers encouraged testing filters in larger samples of patients with controlled exposure to DE.

Reference

Vieira JL, Guimaraes GV, de Andre PA, Cruz FD, Nascimento Saldiva PH, Bocchi EA. Respiratory filter reduces the cardiovascular effects associated with diesel exhaust exposure. A randomized, prospective, double-blind, controlled study of heart failure: The FILTER-HF Trial. JACC Heart Fail. 2016;4(1):55-64. http://dx.doi.org/10.1016.j.jchf.2015.07.018.