Impact of chronic obstructive pulmonary disease on exercise ventilatory efficiency in heart failure

Abstract

Background: Heart failure (HF) and chronic obstructive pulmonary disease (COPD) coexistence increases morbidity and mortality. the intercept of ventilation ((V) over dotEint) on the (V) over dotE vs. carbon dioxide production ((V) over dot CO2) relationship during exercise has been found to vary in proportion with dead space (VD) in HF. Considering that increased VD is the key pathophysiological abnormality in COPD but a secondary finding in HF we hypothesized that a high (V) over dotEint would be useful in suggesting COPD as HF co-morbidity. Our aim was to assess whether an elevated (V) over dotEint suggests the presence of COPD in HF.Methods: in a multicenter retrospective study, the (V) over dotE-(V) over dotCO(2) relationship was analyzed both as slope and intercept in HF (n = 108), HF-COPD (n = 106) and COPD (n = 95). Patients with pulmonary arterial hypertension (PAH) (n= 85) and healthy subjects (HF) (n= 56) served as positive and negative controls relative to (V) over dotE-(V) over dotCO(2) abnormalities, respectively.Results: Slope and (V) over dotEint varied in opposite directions in all groups (p < 0.05) being (V) over dotE-(V) over dotCO(2) slope highest and lowest in PAH and healthy subjects, respectively. No slope differences were observed among HF, HF-COPD and COPD (32 +/- 7, 31 +/- 7, and 31 +/- 6, respectively). (V)over dotEint was higher in HF-COPD and COPD compared to HF, PAH and controls (4.8 +/- 2.4 L/min, 5.9 +/- 3.0 L/min, 3.0 +/- 2.6 L/min, 2.3 +/- 3.3 L/min and 3.9 +/- 2.5 L/min, respectively; p < 0.01). A (V) over dotEint >= 4.07 L/min identified patients with high probability of having COPD or HF-COPD (sensitivity of 71.6% and specificity of 72.0%).Conclusion: These data provide novel evidence that a high (V) over dotEint (>= 4.07 L/min) should be valued to suggest coexistent COPD in HF patients. (C) 2015 Elsevier Ireland Ltd. All rights reserved.