Cardiovascular Response During 6-Minute Walk Test in Patients with Stable COPD

<bold>Introduction:</bold> The 6-minute walk test (6MWT) is a submaximal exercise test used for functional assessment in COPD. We examined the cardiovascular response during 6MWT in stable COPD patients stratified according to the GOLD ABE classification. <bold>Methods:</bold> Stable consecutive COPD patients were recruited and classified as per GOLD groups based on symptom scores and history of exacerbations. Spirometry and 6 MWT were performed as per standard protocols. The following definitions were used: Heart rate recovery (HRR) is the difference in maximum HR during 6MWT and 1 minute later. Slow heart rate recovery (SHRR) was defined as HRR <10. <bold>Results:</bold> We included 205 COPD patients, with a mean age of 63.25 years. The majority of our patients were from Group B (55.12%), followed by Group E (26.82%). The SHRR was observed in 41.5% of patients. We found a significant difference in 6MWD (405.81 meters vs. 363. 30 meters, p<0.05), heart rate immediately after 6MWT (105 bpm vs. 111 bpm, p<0.05), HR 1 minute after 6MWT (91 bpm vs. 100 bpm, p<0.05), HR 2 minutes after 6MWT (88 bpm vs. 96 bpm, p<0.05), and percentage of predicted heart rate reserve (33.35% vs. 27.67%, p<0.05) between groups A and E. Also, there were significant differences in post-6MWT oxygen saturation (92.83 vs. 90.16, p<0.05) and post-6MWT Borg score (1.89 vs. 3.65, p<0.05) between groups A and E. We did not notice any significant difference in systolic and diastolic blood pressure between these groups. <bold>Conclusion:</bold> Slow heart rate recovery is seen in a substantial number of COPD patients. Higher GOLD groups have a poor cardiovascular response after 6 MWT.