Key result
In non-obstructive patients with exercise intolerance and coronary artery disease, a one standard deviation increase in FEV1 was associated with a 1.4 ml/kg/min higher peak oxygen uptake.
Why the study?
Reduced VO2peak in CAD is assumed to reflect cardiovascular limitation, but the influence of normal pulmonary function on overall exercise capacity remained unclear.
Are normal values of lung function measures (FEV1, TLCO, TLCO/VA) associated with peak oxygen uptake (VO2peak) in patients with coronary artery disease and exercise intolerance?
Cross-Sectional (n=93)
No
Are normal values of lung function measures (FEV1, TLCO, TLCO/VA) associated with peak oxygen uptake (VO2peak) in patients with coronary artery disease and exercise intolerance?
In non-obstructive patients with CAD and exercise intolerance, normal lung function measures are positively associated with peak oxygen uptake, suggesting pulmonary function influences exercise capacity even without overt lung disease.
Pulmonary measures may influence exercise capacity in non-obstructive CAD; hypothesis-generating, prospective studies needed before clinical adoption.
In coronary artery disease (CAD), exercise intolerance with reduced oxygen uptake at peak exercise (VO2peak) is assumed to primarily reflect cardiovascular limitation. However, oxygen transport and utilization depends on an integrated organ response, to which the normal pulmonary system may influence overall capacity. This study aimed to investigate the associations between normal values of lung function measures and VO2peak in patients with exercise intolerance and CAD. We hypothesized that forced expiratory lung volume in one second (FEV1), transfer factor of the lung for carbon monoxide (TLCO) and TLCO/alveolar volume (TLCO/VA) above lower limits of normal (LLN) are associated with VO2peak in these patients. We assessed patients with established CAD (n = 93; 21 women) referred for evaluation due to exercise intolerance from primary care to a private specialist clinic in Norway. Lung function tests and cardiopulmonary exercise testing (CPET) were performed. Z-scores of FEV1, FEV1/forced vital capacity (FVC), TLCO and TLCO/VA were calculated using the Global Lung Function Initiative (GLI) software and LLN was defined as the fifth percentile (z = -1.645). Non-obstructive patients, defined by both FEV1 and FEV1/FVC above LLN, were assessed. The associations of FEV1Z-score, TLCOZ-score and TLCO/VAZ-score above LLN with VO2peak were investigated using linear regression models. Mean VO2peak ± standard deviation (SD) was 23.8 ± 6.4 ml/kg/min in men and 19.7 ± 4.4 ml/kg/min in women. On average, one SD increase in FEV1, TLCO and TLCO/VA were associated with 1.4 (95% CI 0.2, 2.6), 2.6 (95% CI 1.2, 4.0) and 1.3 (95% CI 0.2, 2.5) ml/kg/min higher VO2peak, respectively. In non-obstructive patients with exercise intolerance and CAD, FEV1, TLCO and TLCO/VA above LLN are positively associated with VO2peak. This may imply a clinically significant influence of normal lung function on exercise capacity in these patients.
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Rasch-Halvorsen et al. (2020) conducted a cross-sectional in Coronary artery disease with exercise intolerance (n=93). Normal lung function (FEV1 above lower limits of normal) was evaluated on Peak oxygen uptake (VO2peak) (Beta 1.4, 95% CI 0.2, 2.6). In non-obstructive patients with exercise intolerance and coronary artery disease, a one standard deviation increase in FEV1 was associated with a 1.4 ml/kg/min higher peak oxygen uptake.
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