BACKGROUND: The 6-minute walk test (6-MWT) assesses exercise capacity in patients with chronic obstructive pulmonary disease. A recent study revealed that selected patients with an advanced emphysema and a baseline walking distance of =140 m in 6-MWT benefit from endoscopic lung volume reduction with valves (ELVR) with a remarkable improvement in walking distance. However, the reasons for these improvements remain unexplained. STUDY DESIGN AND METHODS: We retrospectively analyzed 54 patients with severe emphysema undergoing ELVR at Charite-Universitaetsmedizin Berlin. Patients were stratified into 2 groups by baseline walking distance: those with 6-MWT =140 m and those with 6-MWT 140-450 m. Changes in lung function, quality of life, and 6-MWT parameters (peripheral oxygen saturation (SpO(2)), heart rate (HR), and walking distance) were evaluated using Generalized Estimating Equations (GEE). RESULTS: While lung function and quality of life improved comparably in both groups, patients with 6-MWT =140 m showed a significantly greater improvement in walking distance versus the 6-MWT 140-450 m group (105.6 +/- 123.2 m versus 12.1 +/- 80.8 m, p=0.027). GEE analysis indicated that this improvement was accompanied by a significantly greater reduction in DeltaHR from baseline to follow-up compared to the 6-MWT 140-450 m group (p=0.023), while changes in SpO(2) were similar. CONCLUSION: Patients with very limited exercise capacity (=140 m) improved their walking distance disproportionately after ELVR. The concomitant decrease in HR suggests an associated cardiovascular benefit in this subgroup. Therefore, a 6-MWT of =140 m should not be considered an exclusion criterion for ELVR, as these patients can achieve meaningful clinical improvements.
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