Efficacy of bronchoscopic thermal vapor ablation and lobar fissure completeness in patients with heterogeneous emphysema

Background: Bronchoscopic thermal vapor ablation (BTVA) ablates emphysematous tissue through a localized inflammatory response followed by contractive fibrosis and tissue shrinkage leading to lung volume reduction that should not be influenced by collateral ventilation. Objectives: To determine the correlation of clinical data from a trial of BTVA with fissure integrity visually assessed by computed tomography (CT). Methods: We conducted a single-arm study of patients with upper lobe-predominant emphysema (n = 44). Patients received BTVA either to the right upper lobe or left upper lobe, excluding the lingula. Primary efficacy outcomes were forced expiratory volume in 1 s (FEV₁) and St. George's Respiratory Questionnaire (SGRQ) at 6 months. Lobar volume reduction from CT was another efficacy outcome measurement. The fissure of the treated lobe was analyzed visually on preinterventional CT. Incompleteness of the small fissure, the upper half of the right large fissure and the whole left large fissure were estimated visually in 5% increments, and the relative amount of fissure incompleteness was calculated. Pearson correlation coefficients were calculated for the association between fissure incompleteness and change in efficacy outcomes (baseline to 6 months) of BTVA. Results: A total of 38 out of 44 patients (86%) had incompleteness in the relevant fissure. Calculated relevant fissure incompleteness was a mean of 13% of fissure integrity (range 0-63). Correlation coefficients for the association of incompleteness with outcomes were as follows: FEV₁ = 0.17; lung volume reduction = -0.27; SGRQ score = -0.10; 6-min walk distance = 0.0; residual volume (RV) = -0.18, and RV/total lung capacity = -0.14. Conclusions: Lobar fissure integrity has no or minimal influence on BTVA-induced lung volume reduction and improvements in clinical outcomes.