Differences in exercise capacity in patients with chronic left heart failure and chronic right heart failure.

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