PURPOSE: Advanced heterogeneous pulmonary emphysema with hyperinflation impacts exercise tolerance in COPD. We evaluated whether baseline perfusion to the target lobe of patients receiving Zephyr® endobronchial valves (EBV) was associated with improvement in 6 minute walk test distance (6MWTD).
METHODS: We performed a retrospective analysis on the treatment group of the VENT trial (N Engl J Med 2010; 363:1233) to evaluate the impact of baseline perfusion, measured by 99mTc-MAA perfusion scintigraphy, on six-month improvement in 6MWTD. A mixed model analysis (SAS, Cary, NC) was performed for the treatment outcome adjusting for other variables such as fissure integrity, target lobe site, age and sex.
RESULTS: Of the 220 patients who received EBV therapy, 193 had complete perfusion scintigraphy data available. Dichotomized at the median, 99 had a low baseline target lobe perfusion and 94 had high target lobe perfusion. Among EBV patients with complete lobar exclusion at follow-up, a low baseline target lobe perfusion was associated with a significant improvement in 6MWTD when compared to high baseline target lobe perfusion (31.1 Vs. 0.9 meters, p < 0.02). The mixed model analysis also suggested interactions with sex, fissure integrity and CT documented target lobe volume reduction.
CONCLUSIONS: Patients having heterogeneous emphysema with a low baseline target lobe perfusion benefit from EBV therapy. This effect is attenuated if the valves are not occlusive and lobar volume fails to decline. Characterization of baseline perfusion may enhance clinical results of emphysema patients undergoing EBV therapy.
CLINICAL IMPLICATIONS: 1) Our findings could potentially help with selection of suitable patients for EBV therapy, resulting in improvement in exercise tolerance and improved quality of life for patients with severe emphysema. 2) Help design future clinical trials comparing EBV therapy with the current standard of care.
DISCLOSURE: The following authors have nothing to disclose: Rahul Argula, Viswanathan Ramakrishnan, Charlie Strange
I will be discussing the use of an endobronchial valve based therapy for severe emphysema. My presentation should be considered as investigational research as this device has not yet been approved for use in patients with emphysema.