Associations of Small-Airway Disease with Exercise Intolerance and Long-Term Outcomes in Patients with Heart Failure...

Small airway is reportedly more susceptible than central airways in heart failure (HF), which may cause poor outcomes. We investigated clinical significance of small-airway disease (SAD) on exercise intolerance and clinical events in patients with HF and reduced or preserved left ventricular ejection fraction (LVEF).

We studied consecutive patients with HF admitted for medical treatment and measured maximum mid-expiratory flow (MMEF) on spirometry and 6-min walking distance (6MWD) at hospital discharge. SAD and exercise intolerance were defined by MMEF relative to <60% of the predicted value and 6MWD <300 m, respectively. Endpoint was composite clinical events of all-cause death and/or HF readmission.

Among 1,016 studied patients, 478 (47.0%) had SAD, the prevalence of which was higher in patients with LVEF ≥40% than LVEF <40%. SAD correlated to 6MWD <300 m (adjusted odds ratio [aOR]: 4.23, 95% confidence interval [CI]: 2.49-7.19). This correlation was consistently observed in both LVEF <40% (aOR: 3.99, 95% CI: 1.59-9.98) and LVEF ≥40% (aOR: 4.50, 95% CI: 2.22-9.13). SAD also showed significant associations with high incidences of clinical events in all patients (adjusted hazard ratio [aHR]: 1.35, 95% CI: 1.05-1.72) and in LVEF <40% (aHR: 1.76, 95% CI: 1.21-2.54) but not in LVEF ≥40% (aHR: 1.10, 95% CI: 0.78-1.53).

The prevalence of SAD is high in patients with HF, which is associated with exercise intolerance regardless of LVEF. Additionally, SAD may have a predictive significance for clinical events in these patients, especially in LVEF <40%.