Poor relationship between exercise capacity and spirometric measurements in patients with more symptomatic heart failure

BACKGROUND: The origin of exercise limitation in patients with chronic heart failure (CHF) is multifactorial, and the relative contributions of different abnormalities may vary with severity of heart failure symptoms. The aim of the current study was to determine the extent to which spirometric indices predict peak exercise capacity in patients with differing severity of symptoms. METHODS AND RESULTS: A total of 340 patients with left ventricular systolic dysfunction underwent spirometry, and a ramped, maximal exercise treadmill test with metabolic gas exchange measurements. For comparative purposes, a group of 174 aged-matched controls with no major structural heart disease (MSHD) was also included. In a stepwise linear regression model, forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) were independent predictors of peak oxygen uptake (pVO2) in controls (r2= 18-25%; P = .001) and New York Heart Association (NYHA) I-II patients (r2= 16-18%; P = .001). No association between spirometric indices (FEV1/FVC) and pVO2 (r2= 1-2%; P > .05) was found in NYHA III-IV patients. CONCLUSION: In aged-matched controls with no MSHD, spirometric variables (FEV1/FVC) explain 18% to 25% of the variance in pVO2, and 16% to 18% of the variance in patients with NYHA class I-II symptoms. As symptoms worsen, the influence of spirometric variables on peak exercise capacity diminishes, and there is no such relation in the NYHA class III-IV patients.