| Summary: | Dongxing Zhao,1,2 Asghar Abbasi,1 Richard Casaburi,1 Alessandra Adami,3 Nicholas B Tiller,1 Wei Yuan,1,4 Christopher Yee,5 Nicholas G Jendzjowsky,1 David M MacDonald,6,7 Ken M Kunisaki,6,7 William W Stringer,1 Janos Porszasz,1 Barry J Make,8 Russell P Bowler,8 Harry B Rossiter1 On behalf of the COPDGene Investigators1Rehabilitation Clinical Trials Center, Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, USA; 2State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, 510120, People’s Republic of China; 3Department of Kinesiology, University of Rhode Island, Kingston, RI, USA; 4Respiratory Medicine Department, Beijing Friendship Hospital Affiliated of Capital Medical University, Beijing, 100050, People’s Republic of China; 5MemorialCare Long Beach Medical Center, Long Beach, CA, USA; 6Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, University of Minnesota, Minneapolis, MN, USA; 7Minneapolis VA Health Care System, Minneapolis, MN, USA; 8National Jewish Health, Denver, CO, USACorrespondence: Harry B Rossiter Email hrossiter@ucla.eduBackground: Slow heart rate recovery (HRR) after exercise is associated with autonomic dysfunction and increased mortality. What HRR criterion at 1-minute after a 6-minute walk test (6MWT) best defines pulmonary impairment?.Study Design and Methods: A total of 5008 phase 2 COPDGene (NCT00608764) participants with smoking history were included. A total of 2127 had COPD and, of these, 385 were followed-up 5-years later. Lung surgery, transplant, bronchiectasis, atrial fibrillation, heart failure and pacemakers were exclusionary. HR was measured from pulse oximetry at end-walk and after 1-min seated recovery. A receiver operator characteristic (ROC) identified optimal HRR cut-off. Generalized linear regression determined HRR association with spirometry, chest CT, symptoms and exacerbations.Results: HRR after 6MWT (bt/min) was categorized in quintiles: ≤ 5 (23.0% of participants), 6– 10 (20.7%), 11– 15 (18.9%), 16– 22 (18.5%) and ≥ 23 (18.9%). Compared to HRR≤ 5, HRR≥ 11 was associated with (p< 0.001): lower pre-walk HR and 1-min post HR; greater end-walk HR; greater 6MWD; greater FEV1%pred; lower airway wall area and wall thickness. HRR was positively associated with FEV1%pred and negatively associated with airway wall thickness. An optimal HRR ≤ 10 bt/min yielded an area under the ROC curve of 0.62 (95% CI 0.58– 0.66) for identifying FEV1< 30%pred. HRR≥ 11 bt/min was the lowest HRR associated with consistently less impairment in 6MWT, spirometry and CT variables. In COPD, HRR≤ 10 bt/min was associated with (p< 0.001): ≥ 2 exacerbations in the previous year (OR=1.76[1.33– 2.34]); CAT≥ 10 (OR=1.42[1.18– 1.71]); mMRC≥ 2 (OR=1.42[1.19– 1.69]); GOLD 4 (OR=1.98[1.44– 2.73]) and GOLD D (OR=1.51[1.18– 1.95]). HRR≤ 10 bt/min was predicted COPD exacerbations at 5-year follow-up (RR=1.83[1.07– 3.12], P=0.027).Conclusion: HRR≤ 10 bt/min after 6MWT in COPD is associated with more severe expiratory flow limitation, airway wall thickening, worse dyspnoea and quality of life, and future exacerbations, suggesting that an abnormal HRR≤ 10 bt/min after a 6MWT may be used in a comprehensive assessment in COPD for risk of severity, symptoms and future exacerbations.Keywords: autonomic dysfunction, chest computed tomography, COPD exacerbation, exercise, spirometry
|
|---|
