Exercise impairment is common in chronic left heart failure and pulmonary arterial hypertension (PAH). Exercise impairment degree is a strong predictor of clinical outcome. Our purpose was to evaluate differences in exercise capacity using cardiopulmonary exercise testing (CPX) in patients with chronic left and right heart failure, and determine which factors were related to exercise impairment.

102 patients with class II/III New York Heart Association were involved in the study (41 with chronic left heart failure, 61 with chronic right heart failure secondary to PAH). All patients underwent CPX to evaluate exercise capacity.

Patients with right heart failure had significantly lower peak oxygen uptake (VO₂), peak VO₂/kg ratio, peak oxygen uptake/heart rate (VO₂/HR) ratio and increases in oxygen uptake/increase in work rate (ΔVO₂/ΔWR) slope, and had higher minute ventilation/CO₂ production ratio and peak dead space volume/tidal volume during exercise. In patients with left heart failure, peak VO₂/HR ratio was positively correlated with ΔVO₂/ΔWR slope. However, VO₂ and VO₂/HR ratio were positively correlated with ΔVO₂/ΔWR slope in patients with right heart failure.

Compared with left heart failure, patients with right heart failure showed worse exercise capacity resulting from worse pulmonary and cardiovascular adaptation to exercise.