Relationship of Lung Function and Inspiratory Strength with Exercise Capacity and Prognosis in Heart Failure

Abstract

Background: Spirometry is underused in heart failure (HF) and the extent to which each defect associates with exercise capacity and prognosis is unclear. Objective: To determine the distinct relationship of continuous %predicted FVC (ppFVC) and FEV1/FVC with: 1) maximal inspiratory pressure (MIP), left ventricular ejection fraction (LVEF), exercise performance; and 2) prognosis for the composite of cardiovascular death, heart transplantation or left ventricular assist device implant. Methods: A cohort of 111 HF participants (AHA stages C/D) without diagnosed pneumopathy, spirometry, manovacuometry and maximum cardiopulmonary test. The association magnitudes were verified by linear and Cox (HR; 95% CI) regressions, age/sex adjusted. A p<0.05 was considered significant. Results: Age was 57±12 years, 60% men, 64% in NYHA III. Every 10%-point increase in FEV1/FVC [β 7% (95% CI: 3–10)] and ppFVC [4% (2-6)] associated with ventilatory reserve (VRes), however only ppFVC associated with MIP [3.8 cmH2 O (0.3-7.3)], LVEF [2.1% (0.5-3.8)] and VO2 peak [0.5 mL/kg/min (0.1–1.0)], accounting for age/sex. In 2.2 years (mean), 22 events occurred, and neither FEV1/FVC (HR 1.44; 95% CI: 0.97–2.13) nor ppFVC (HR 1.13; 0.89–1.43) was significantly associated with the outcome. Only in the LVEF ≤50% subgroup (n=87, 20 events), FEV1/FVC (HR 1.50; 1.01–2.23), but not ppFVC, was associated with greater risk. Conclusions: In chronic HF, reduced ppFVC associated with lower MIP, LVEF, VRes and VO2 peak, but no distinct poorer prognosis over 2.2 years of follow-up. Distinctively, FEV1/FVC was associated only with VRes, and, in participants with LVEF ≤50%, FEV1/FVC reduction proportionally worsened prognosis. Therefore, FEV1/FVC and ppFVC add supplementary information regarding HF phenotyping.