Volume changes after segmental vapor ablation and associated improvements in FEV1

Introduction: The recent STEP-UP trial showed clinically relevant improvements in lung function and quality of life associated with segmental upper lobe vapor ablation. Objective: To correlate changes in segmental volumes of treated and untreated segments with FEV1. Methods: In the STEP-UP study patients with bilateral, upper-lobe predominant emphysema underwent vapor ablation of 1-2 segments of each upper lobe. Quantitative software (VIDA, Coralville, IA) was used to assess relative segmental volume changes from baseline to 6-month follow-up CT scans. Results: Data from 40 treated patients (21f/19m, FEV1 34±8%, RV 236±41%) with complete data sets were included. Vapor ablation resulted in a statistically significant 36±17% segmental volume reduction at emphysematous treatment sites and an 8±9% volume increase of untreated preserved lung segments (p < 0.01) Volume reduction of treated segments correlated positively with the absolute improvement in FEV 1 at 6 months (r=0.47) Conclusions: Targeted segmental vapor ablation and subsequent volume reduction of the most diseased upper lobe segments induced expansion of preserved, relatively healthy upper lobe segments.