Respiratory filter reduces the cardiovascular effects associated with diesel exhaust exposure: a randomized, prospective, double-blind, controlled study of heart failure (FILTER-HF Trial)

BACKGROUND: Air pollution is considered a risk factor for heart failure (HF) decompensation and mortality. The effects of respiratory filters on patients with HF exposed to air pollution have not been established. OBJECTIVE: To test the effects of a respiratory filter intervention (filter) during controlled pollution exposure METHODS: Double-blind, randomized to order and 3-way crossover study with 26 HF patients and 15 control volunteers. Participants were exposed in three separate sessions to: clean air, diesel exhaust exposure (DE) or filtered-DE. Endpoints were endothelial function via reactive hyperemia index (RHi), and arterial stiffness (Aix), serum biomarkers, variables from submaximal cardiopulmonary exercise test (sixminute walk test [6mwt]; oxygen uptake [VO2]; ventilation and carbon dioxide production ratio [VE/VCO2 slope]; oxygen uptake per heart beat [O2Pulse]), and heart rate variability (HRV). RESULTS: In patients with HF, DE was associated with a worsening in RHi [from 2.17 (IQR: 1.8-2.5) to 1.72 (IQR: 1.5-2.2); p=0.002]; a decline in VO2 [from 11.0±3.9 to 8.4±2.8ml/Kg/min; p<0.001], 6mwt [from 243.3±13.0 to 220.8±13.7m; p=0.030] and O2Pulse [from 8.9±1.0 to 7.8±0.7ml/beat; p<0.001] and a rise in BNP [from 47.0pg/ml (IQR: 17.3-118.0) to 66.5pg/ml (IQR: 26.5-155.5); p=0.004]. Filtration reduced the particulate concentration (from 325±31 to 25±6µg/m3; p<0.001 vs. DE). In the HF group, filter was associated with an improvement in RHi [2.06 (IQR: 1.5-2.6); p=0.019 vs. DE]; an increase in VO2 (10.4±3.8ml/Kg/min; p<0.001 vs. DE) and O2Pulse (9.7±1.1ml/beat; p<0.001 vs. DE); and also a decrease in BNP [44.0pg/ml (IQR: 20.0-110.0); p=0.015 vs. DE]. In both groups DE decreased Aix, however filtration did not change these responses. In both groups, filtration was associated with higher pulmonary ventilation and CO2 rebreathing. Other variables as VE/VCO2 slope and HRV did not differ between exposure protocols. CONCLUSION: Air pollution adversely affects cardiovascular performance in HF patients. To our knowledge, this is the first trial demonstrating that a simple respiratory-filter can prevent endothelial dysfunction; exercise intolerance and BNP rise in patients with HF during DE. Given these potential benefits, the widespread use of filters in HF subjects exposed to traffic-derived air pollution may have beneficial public health impacts and reduce the burden of HF.