Résumé : Left ventricular (LV) function was studied, using echocardiography, radionuclide angiography and right catheterization, in 20 patients (mean age 60.9 +/- 1.5 years) with severe stable chronic obstructive pulmonary disease (COPD) and without known heart disease. The diagnosis of LV failure, suspected on clinical grounds in 8 of these patients, was confirmed by raised pulmonary capillary wedge pressure (PCWP) in only one patient. Nineteen subjects had normal PCWP and LV ejection fraction (LVEF) values, radionuclide LVEF and end diastolic LV dimension being the most powerful discriminators between the single abnormal patient and the others. Echocardiograms of sufficient quality were obtained in 11 out of the 19 normal patients and constantly showed LV dimensions in the lowest part of the normal range. The stroke volume index (SVI) - cardiac output being measured by thermodilution - was found to be decreased in 9 of 14 patients with normal LVEF values. We conclude that in patients with severe COPD (1) LV failure is quite unfrequent and the empirical use of digitalis should not be recommended, (2) radionuclide angiography is the most useful procedure for routine evaluation of LV function and (3) a decreased SVI is frequently found in patients with a small LV cavity and a normal LVEF, suggesting some degree of diastolic dysfunction of the left ventricle.