Measurement of exhaled nitric oxide fails to predict left atrial pressure assessed by E/e ratio in elderly patients

Background During left-sided heart failure, left atrial and pulmonary venous pressure increase, which may lead to pulmonary congestion. Previous cohort studies examining participants with symptomatic heart failure or rheumatic heart disease suggest a relationship between increased left atrial pressure (LAP) and fractional exhaled nitric oxide (FeNO).

Aim In this study, we examined the strength of association between FeNO and echocardiographic assessment of LAP by the E/e’ ratio to determine if FeNO could be used to identify those with elevated LAP. Office-based diagnostic testing for heart failure could be improved if such a relationship exists, as FeNO can be measured using a portable hand-held analyser.

Design and Setting This cross-sectional cohort study examined a subset of the OxVALVE cohort aged >65 years. Data collection was undertaken in primary care practices in central England.

Method Each participant underwent a focused cardiovascular history and clinical examination. Standard transthoracic echocardiographic (TTE) assessment was performed on all participants, with the E/e’ ratio calculated to obtain a validated surrogate of LAP. FeNO was measured in 227 participants.

Results FeNO was higher in men and no different in participants with asthma, chronic obstructive airways disease, or using inhaled steroids. Participants with a high E/e’ (>14) were older with a higher proportion of women. There was no relationship between E/e’ and FeNO, either when measured as a continuous variable or in the group with high E/e’.

Conclusion FeNO is not an accurate predictor of elevated left atrial pressure in a primary care setting.