Abstract
Rationale: The chronotropic index quantifies the proportion of the expected heart rate increase that is attained during exercise. The relationship between the chronotropic index and acute exacerbations of chronic obstructive pulmonary disease (AECOPDs) has not been evaluated. Objectives: To determine whether a higher chronotropic index during a 6-minute walk (CI-6MW) is associated with lower risk of AECOPD and whether the CI-6MW is a marker of susceptibility to adverse effects of metoprolol in chronic obstructive pulmonary disease (COPD). Methods: We analyzed data from the BLOCK COPD (Beta-Blockers for the Prevention of AECOPDs) trial. We used Cox proportional hazards models to investigate the relationship between the CI-6MW and the time to AECOPDs. We also tested for interactions between study group assignment (metoprolol vs. placebo) and the CI-6MW on the time to AECOPDs. Results: Four hundred seventy-seven participants with exacerbation-prone COPD (mean forced expiratory volume in 1 second, 41% of predicted) were included in this analysis. A higher CI-6MW was independently associated with a decreased risk of AECOPDs of any severity (adjusted hazard ratio per 0.1 increase in CI-6MW of 0.88; 95% confidence interval, 0.80–0.96) but was not independently associated with AECOPDs requiring hospitalization (adjusted hazard ratio, 0.94; 95% confidence interval, 0.81–1.05). There was a significant interaction by treatment assignment, and in a stratified analysis, the protective effects of a higher CI-6MW on AECOPDs were negated by metoprolol use. Conclusions: A higher CI-6MW is associated with a decreased risk of AECOPDs and may be an indicator of susceptibility to the adverse effects of metoprolol.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1795-1802 |
| Number of pages | 8 |
| Journal | Annals of the American Thoracic Society |
| Volume | 18 |
| Issue number | 11 |
| DOIs | |
| State | Published - Nov 2021 |
Bibliographical note
Funding Information:*These authors contributed equally to this work. A complete list of BLOCK COPD Study Investigators may be found in the online supplement. The BLOCK COPD (Beta-Blockers for the Prevention of Acute Exacerbations of Chronic Obstructive Pulmonary Disease) trial was supported by a grant from the Department of Defense (W81XWH-15-1-0705). D.M.M. was supported by the University of Minnesota T32 Training in Lung Science training grant (2T32HL007741-26A1). This material is also the result of work supported with resources and the use of facilities at the Minneapolis Veterans Affairs Medical Center, Minneapolis, Minnesota. The views expressed in this article are those of the authors and do not reflect the views of the U.S. Government, the Department of Defense, the Department of Veterans Affairs, or any of the authors’ affiliated academic institutions.
Funding Information:
The BLOCK COPD (Beta-Blockers for the Prevention of Acute Exacerbations of Chronic Obstructive Pulmonary Disease) trial was supported by a grant from the Department of Defense (W81XWH-15-1-0705). D.M.M. was supported by the University of Minnesota T32 Training in Lung Science training grant (2T32HL007741-26A1). This material is also the result of work supported with resources and the use of facilities at the Minneapolis Veterans Affairs Medical Center, Minneapolis, Minnesota. The views expressed in this article are those of the authors and do not reflect the views of the U.S. Government, the Department of Defense, the Department of Veterans Affairs, or any of the authors? affiliated academic institutions.
Publisher Copyright:
© 2021 by the American Thoracic Society
Keywords
- Cardiac chronotropy
- Chronic obstructive
- Disease exacerbation
- Pulmonary disease
