Exercise testing in pulmonary arterial hypertension and in chronic heart failure

Exercise capacity is reduced in pulmonary arterial hypertension and in chronic left heart failure, but it is not known whether the cardiopulmonary exercise testing profile is different in the two conditions at the same severity of functional limitation. Nineteen patients with pulmonary arterial hypertension and 19 with chronic heart failure underwent a 6-min walk test and symptom-limited maximal incremental cycle ergometry. The patients with pulmonary arterial hypertension and chronic heart failure did not differ in New York Heart Association Functional Class (mean +/- SEM 2.8 +/- 0.1 versus 2.8 +/- 0.2), 6-min walking distance (395 +/- 30 versus 419 +/- 20 m), peak work-rate, oxygen consumption, ventilation and cardiac frequency. However, patients with pulmonary arterial hypertension exhibited higher dyspnoea scores (5.8 +/- 0.6 versus 3.8 +/- 0.5) higher ventilatory equivalents for carbon dioxide (58 +/- 3 versus 44 +/- 3 at the anaerobic threshold) and lower peak oxygen pulse (5.9 +/- 0.4 versus 8.7 +/- 0.5 mL x beat(-1), or 53 +/- 4 versus 64 +/- 4% of the predicted value). It is concluded that the cardiopulmonary exercise testing profile in pulmonary arterial hypertension differs from that in chronic heart failure by showing more dyspnoea at comparable work-rates, related to greater reductions in ventilatory efficiency and stroke volume.