Aldabayan, Yousef; (2019) Pulmonary Rehabilitation and Cardiovascular Risk in COPD. Doctoral thesis (Ph.D), UCL (University College London.

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Abstract

Introduction: Patients with chronic obstructive pulmonary disease (COPD) have elevated cardiovascular risk, and cardiovascular disease is a major cause of death in COPD. The current literature indicates that changes in cardiovascular risk during pulmonary rehabilitation (assessed using aortic stiffness) are heterogeneous, suggesting that there may be sub-groups of patients who do and do not benefit. In COPD, cardiovascular comorbidity is common in patients hospitalised with exacerbations of COPD and this may negatively affect exacerbation recovery. Aim: To investigate the characteristics of COPD patients who do and do not experience aortic stiffness reduction during pulmonary rehabilitation, examine how changes relate to physical activity and exercise capacity, and assess whether changes in aortic stiffness are maintained at six weeks following rehabilitation. To identify the possibility of subsequent CV risk reduction during hospitalisation (from admission towards discharge). Methods: Firstly, a systematic review was conducted to assess the existing literature on the influence of pulmonary rehabilitation on cardiovascular risk in COPD measured by aortic pulse wave velocity. Next, we conducted a repeatability study to assess and understand the aPWV values generated by Vicorder (Skidmore Medical, Bristol, UK) software in healthy subjects prior to using it on patients. To better understand our population, we conducted a pre-pulmonary rehabilitation study to identify the associations of baseline cardiovascular risk in COPD patients, measured using aPWV, and to compare the results between groups with and without a reported history of CVD. The listed projects enabled the formulation of the research question and main PhD hypothesis, tested using a prospective cohort trial. Participants were enrolled in a PR course consisting of sessions two hours long, twice each week for six weeks, with complete pre- and post-measures, including aPWV. Next, we conducted a follow-up study to identify if there were any alterations in aortic stiffness following the completion of pulmonary rehabilitation. Lastly, we conducted a pilot study to understand whether cardiovascular risk (measured by aortic stiffness) is reduced in hospitalised COPD patients during exacerbation recovery towards discharge. Results: Existing studies that measured aPWV prior to and post-PR were small and heterogeneous with different sample sizes and programme length. The elevated aortic stiffness in COPD was independent from CVD history. Whilst on average there was no influence of PR on aortic stiffness, we report that 56% of patients responded with a significant reduction in aortic stiffness (11.5 vs 10.4m/s, p=<0.001). The change in aortic stiffness during rehabilitation was associated with both increased physical the respondents, 92% of the responders who attended maintained this response six week later. Finally, the elevated aortic stiffness seen in COPD hospitalised due to exacerbation was reduced at discharge (10.3 vs 10.1m/s, p=0.04). Conclusion Elevated aortic stiffness in COPD is potentially modifiable in a subgroup of patients during pulmonary rehabilitation and is associated with increased physical activity; this reduction is maintained at least six weeks later. In contrast, patients who appeared to have an increase in their aortic stiffness during PR were more likely to have a delayed PR response. For those COPD patients hospitalised due to exacerbation, aortic stiffness is reduced toward discharge.

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