title: Baseline regional perfusion impacts exercise response to endobronchial valve therapy in advanced pulmonary emphysema.
abstract: BACKGROUND
  Advanced heterogeneous emphysema with hyperinflation impacts exercise tolerance in COPD. Bronchoscopic lung volume reduction using Zephyr endobronchial valves (EBVs) has been shown to improve lung function in patients with heterogeneous emphysema. It is unclear whether the target lobe perfusion of patients receiving EBV therapy impacts exercise tolerance as measured by the 6-min walk test distance (6MWTD).
  
  
  METHODS
  We performed a retrospective analysis on the treatment group of the Endobronchial Valve for Emphysema Palliation Trial (VENT) to evaluate the impact of perfusion, measured by 99mTc-MAA-perfusion scintigraphy, on the 6-month improvement in 6MWTD. A mixed-model analysis was performed for the treatment outcome, adjusting for other variables such as age, target lobe position, fissure integrity, BMI, sex, destruction score, and lobar exclusion.
  
  
  RESULTS
  Dichotomized at the median, of the 169 patients who received EBV therapy, 88 had a low target lobe regional perfusion and 81 had high target lobe regional perfusion at baseline. Patients with a low target lobe regional perfusion had a significant improvement in 6MWTD when compared with those with a high baseline target lobe regional perfusion (30.24 m vs 3.72 m, P = .03). Shifts in perfusion after EBV therapy occurred only in patients with high baseline perfusion and did not correlate with improved 6MWTD.
  
  
  CONCLUSIONS
  Patients having heterogeneous emphysema with a low baseline target lobe regional perfusion benefit from EBV therapy, independent of the degree of target lobe destruction. This effect is attenuated if the EBV therapy is not occlusive. Characterization of baseline perfusion may enhance clinical results of patients with emphysema undergoing EBV therapy.
  
  
  BACKGROUND
  ClinicalTrials.gov; No.: NCT00000606; URL: www.clincialtrials.gov.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Medical University of South Carolina, Charleston, SC. Electronic address: argula@musc.edu.
authors.forename: Rahul G
authors.initials: RG
authors.lastname: Argula
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Medical University of South Carolina, Charleston, SC.
authors.forename: Charlie
authors.initials: C
authors.lastname: Strange
authors.affiliation: Division of Epidemiology and Biostatistics, Medical University of South Carolina, Charleston, SC.
authors.forename: Viswanathan
authors.initials: V
authors.lastname: Ramakrishnan
authors.affiliation: Department of Radiology, University of California, Los Angeles, CA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Goldin
mesh_terms: D000368:Aged; D001999:Bronchoscopy / Q000379:methods*; D017079:Exercise Tolerance; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D055420:Perfusion Imaging; D011013:Pneumonectomy / Q000379:methods*; D011446:Prospective Studies; D011656:Pulmonary Emphysema / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery; D011788:Quality of Life; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome