Oral Nitrate Reducing Capacity and Aerobic Fitness is Impaired in Older Individuals with Heart Failure with Reduced Ejection Fraction

Background: Nitric oxide (NO) is essential for cardiovascular health and is purported as an ergogenic aid. Endothelial dysfunction and reduced endogenous NO production are hallmarks of heart failure (HF), which may contribute to impaired exercise capacity. Oral inorganic nitrate supplementation offers an exogenous route to increase bioavailable NO via reduction of nitrate by oral commensal bacteria. However, individuals with HF with reduced ejection fraction (HFrEF) display blunted increases in plasma nitrite and inconsistent improvements in exercise tolerance following supplementation. Thus, the purpose of this study was to examine whether bacterial oral nitrate reducing capacity (ONRC) and markers of exercise capacity are impaired in patients with HFrEF compared with age-matched, healthy controls. Methods: Nine individuals with HFrEF (Age: 74.89±7.40y., VO 2peak : 15.17±4.23 ml/kg/min; 5 females, 4 males) and 9 healthy controls (CON) (Age: 71.89±4.23y., VO 2peak : 24.25±2.86 ml/kg/min; 4 females, 5 males) completed a VO 2peak test, ONRC assessment, and measures of salivary and plasma N-oxides. Results: ONRC and saliva nitrite were lower in HFrEF ( p=0.010 and p=0.018, respectively). ONRC for all participants was correlated with VO 2peak (ρ=0.68; p=0.002) and VO 2 at VT ( ρ=0.81; p< 0.001), though this relationship was not significant within groups. Conclusion: These data are first to suggest that ONRC may be impaired in HFrEF compared to age-matched, healthy adults. Future research in a larger sample is needed to determine if ONRC is associated with functional capacity in HFrEF.