Study objectives: The aim of this study was to examine the role of resting pulmonary function and hemodynamic parameters as predictors of exercise capacity in patients with chronic heart failure.
Measurements and results: Fifty-one patients with chronic heart failure underwent resting pulmonary function testing, including inspiratory capacity (IC) and symptom-limited, treadmill cardiopulmonary exercise testing (CPET). Right-heart catheterization and radionuclide ventriculography were performed within 2 days of CPET. Mean (± SD) left ventricular ejection fraction was 31 ± 12% and cardiac index was 2.34 ± 0.77 L/min/m2. Percentage of predicted FEV1 was 92 ± 14%, percentage of predicted FVC was 94 ± 15%, FEV1/FVC was 81 ± 4%, and percentage of predicted IC was 84 ± 18%. Mean peak oxygen uptake (peak V̇o2) was 17.9 ± 5.4 mL/kg/min. Analysis of variance among the three functional Weber classes showed statistically significant differences for pulmonary capillary wedge pressure (PCWP) and IC. Specifically, the more severe the exercise intolerance, the lower was IC and the higher was PCWP. In a multivariate stepwise regression analysis, using peak V̇o2 (liters per minute) as the dependent variable and the pulmonary function test measurements as independent variables, the only significant predictor selected was IC (r = 0.71, p < 0.0001). In a final stepwise regression analysis including all the independent variables of the resting pulmonary function tests and hemodynamic measurements, the two predictors selected were IC and PCWP (r2 = 0.58).
Conclusions: In patients with chronic heart failure, IC is inversely related to PCWP and is a strong independent predictor of functional capacity.