Exercise Ventilatory Efficiency in Older and Younger Heart Failure Patients With Preserved Ejection Fraction

Background: Patients with heart failure with preserved ejection fraction (HFpEF) exhibit pulmonary abnormalities, but the studies to date have reported wide variability in the ventilatory equivalent for carbon dioxide ((V) over dot(E)/(V) over dotCO(2)) slope. It is possible that aging may contribute to that variability. We sought to compare ventilatory efficiency and its components in older and younger HFpEF patients during exercise. Methods and Results: Eighteen older (O; 80 +/- 4 y) and 19 younger (Y; 59 +/- 7 y) HFpEF patients performed cardiopulmonary exercise testing to volitional fatigue. Measurements of arterial blood gases were used to derive V-D/V-T, dead space ventilation, and alveolar ventilation. (V) over dot(E)/(V) over dotCO(2) slope was greater in older compared with younger HFpEF patients (O 36 +/- 7 vs Y 31 +/- 7; P = .04). At peak exercise, older HFpEF exhibited greater V-D/V-T compared with younger HFpEF (O 0.37 +/- 0.10 vs Y 0.28 +/- 0.10; P < .01), whereas PaCO2 was not different between groups (P = .58). (V) over dot(E) and alveolar ventilation were similar (P > .23), but dead space ventilation was greater in older compared with younger HFpEF at peak exercise (P = .04). Conclusions: Older HFpEF patients exhibit greater ventilatory inefficiency resulting from elevated physiologic dead space during peak exercise compared with younger HFpEF patients. These results suggest that aging can worsen the pathophysiologic mechanisms underlying ventilatory efficiency during exercise in HFpEF.