OBJECTIVE To clarify the relative contribution of resting haemodynamic profile and pulmonary function to exercise capacity in patients with heart failure.

SETTING Cardiology department and cardiac rehabilitation unit in a tertiary centre.

DESIGN 161 male patients (mean (SD) age 59 (9) years) with heart failure (New York Heart Association class II–IV, left ventricular ejection fraction 23 (7)%) underwent spirometry, alveolar capillary diffusing capacity (DLCO), and mouth inspiratory and expiratory pressures (MIP, MEP, respectively, in 100 patients). Right heart catheterisation and a symptom limited cardiopulmonary exercise test were performed in 137 patients within 3–4 days.

RESULTS Mean peak exercise oxygen consumption (V˙o ₂) was 13 (3.9) ml/kg/min. Among resting haemodynamic variables only cardiac index showed a significant correlation with peakV˙o ₂. There were no differences in haemodynamic variables between patients with peakV˙o ₂ ⩽ or > 14 ml/kg/min. There was a moderate correlation (p < 0.05) between several pulmonary function variables and peak V˙o ₂. Forced vital capacity (3.5 (0.9) v 3.2 (0.8) l, p < 0.05) and DLCO (21.6 (6.9) v 17.7 (5.5) ml/mm Hg/min, p < 0.05) were higher in patients with peakV˙o ₂ > 14 ml/kg/min than in those with peak V˙o ₂ ⩽ 14 ml/kg/min. Using a stepwise regression analysis, the respiratory and haemodynamic variables which correlated significantly with peakV˙o ₂ were DLCO, MEP, and cardiac index, with an overall R value of 0.63.

CONCLUSIONS The data confirm previous studies showing a poor correlation between resting indices of cardiac function and exercise capacity in heart failure. However, several pulmonary function variables were related to peak exerciseV˙o ₂. In particular, lung diffusing capacity and respiratory muscle function seem to affect exercise tolerance during heart failure.