Outcomes Research in Review

Endobronchial Valves for Severe Emphysema

Kemp SV, Slebos DJ, Kirk A, et al; for the TRANSFORM Study Team. A multicenter randomized controlled trial of Zephyr endobronchial valve treatment in heterogeneous emphysema (TRANSFORM). Am J Respir Crit Care Med 2017;196:1535–43.


 

References

Study Overview

Objective. To evaluate the efficacy and safety of Zephyr endobronchial valves (EBVs) in patients with heterogeneous emphysema and absence of collateral ventilation.

Design. Multicenter, randomized, nonblinded clinical trial.

Setting and participants. This study was conducted at 17 sites across Europe between 2014 and 2016. Patients with severe emphysema who were ex-smokers and ≥ 40 years old were recruited. Key inclusion criteria were post-bronchodilator FEV1 between 15%–45% predicted despite optimal medical management, total lung capacity greater than 100% predicted, residual volume ≥ 180% predicted, and a 6-minute walk distance of between 150 and 450 meters. Heterogenous emphysema was defined as a greater than 10% difference in destruction score between target and ipsilateral lobes as measured by high-resolution CT. All eligible patients underwent Chartis pulmonary assessment (Pulmonx, Redwood City, CA) assessment to determine the presence of collateral ventilation between the target and adjacent lobes, and patients with collateral ventilation were excluded.

Intervention. Patients were randomized 2:1 to either EBV plus standard of care (intervention) or standard of care alone (control) by blocked design and concealed envelopes. The EBV group underwent immediate placement of Zephyr EBVs with the intention of complete lobar occlusion.

Main outcome measures. The primary outcome at 3 months post-procedure was the percentage of subjects with FEV1 improvement from baseline of 12% or greater. Changes in FEV1, residual volume, 6-minute walk distance, St. George’s Respiratory Questionnaire score and modified Medical Research Council score were assessed at 3 and 6 months and target lobe volume reduction on chest CT at 3 months.

Main results. 97 subjects were randomized to the intervention (n = 65) or control group (n = 32). At 3 months, 55.4% of intervention and 6.5% of control subjects had an FEV1 improvement of 12% or more (P < 0.001). Improvements were maintained at 6 months: intervention, 56.3%, versus control, 3.2% (P < 0.001), with a mean ± SD change in FEV1% at 6 months of 20.7 ± 29.6% and –8.6 ± 13.0%, respectively. A total of 89.8% of intervention subjects had target lobe volume reduction greater than or equal to 350 mL (mean, 1.09 ± 0.62 L; P < 0.001). The differences in outcomes between the intervention and control groups were statistically significant, with the following measured differences: residual volume, –700 m; 6-minute walk distance, +78.7 m; St. George’s Respiratory Questionnaire score, –6.5 points; modified Medical Research Council dyspnea score, –0.6 points; and BODE (body mass index, airflow obstruction, dyspnea, and exercise capacity) index, –1.8 points (all P < 0.05). Pneumothorax was the most common adverse event, occurring in 19 of 65 (29.2%) of intervention subjects.

Conclusion. Endobronchial valve treatment in hyperinflated patients with heterogeneous emphysema without collateral ventilation resulted in clinically meaningful benefits in lung function, dyspnea, exercise tolerance and quality of life, with an acceptable safety profile.

Commentary

Patients with severe emphysema are difficult to manage. Optimal medical management is required to maintain their lung function and quality of life, with combination bronchodilators (long-acting beta 2 agonists, long-acting anticholinergics, and inhaled corticosteroids), roflumilast (selective phosphodiesterase-4 inhibitors), oral corticosteroids or macrolide antibiotics when indicated, long-term oxygen, and noninvasive ventilator support. Palliative team care consultation and support, adequate nutritional support, influenza and pneumococcal vaccination, and pulmonary rehabilitation/graded exercise training are important aspects of emphysema treatment [1].

To help patients with severe emphysema who experience further decline despite intensive medical management, a lung volume reduction strategy was devised. In 2003, the NETT trial was conducted [2]. In this study, lung volume reduction surgery was performed in 608 patients, who were followed for 29 months. This study revealed a lack of survival benefit with significant immediate postoperative mortality and complication rate. Despite this disappointing result, a subgroup of patients (upper-lobe predominant disease and low baseline exercise capacity) had a statistically significant mortality benefit from surgery.

Since then, many have sought to determine a less invasive method of lung volume reduction. So far, one-way endobronchial valves, self-activating coils, and targeted destruction and remodeling of emphysematous lung with vapor or sealant methods have been studied. Several studies have examined the efficacy and safety of coils, with reasonable improvement of 6-minute walk distance and FEV1; however, complications including death, pneumothorax and pneumonia were noted. Vapor ablation (STEP-UP trial) [3] and lung sealant [4] were also attempted in order to achieve lung volume reduction, but increased infection was problematic. The 2017 GOLD guidelines suggested lung volume reduction by endobronchial one-way valve or lung coils as interventional bronchoscopic options for lung volume reduction [1].

Two types of endobronchial valves have been introduced to date: the intra bronchial valve, developed by Olympus, and the Zephyr valve by Pulmonx. Endobronchial valves are deployed to the bronchi via bronchoscopic guidance, and limit airflow to the portions of the lung distal to the valve while allowing mucus and air movement in the proximal direction. The VENT study, the largest endobronchial valve trial using the Zephyr valve, was published in 2010 [5]. This study demonstrated the efficacy of endobronchial valve treatment, especially in patients with heterogeneous emphysema and complete interlobar fissures as opposed to homogeneous emphysema and incomplete interlobar fissures. Subsequent studies demonstrated the importance of absence of collateral ventilation, measured by the Chartis system, when considering endobronchial valves [6].

The current study by Kemp et al is the first multicenter randomized endobronchial valve trial conducted in Europe. The study was able to demonstrate remarkable improvement in FEV1 (mean 140 mL decrease vs 90 mL increase) and 6-minute walk distance (mean +36.2 meter vs –42.5 meter) after endobronchial valve treatment in severe emphysema patients. The amount of volume reduction was reaching up to 2 liters. Patients in the control group were given the opportunity to receive endobronchial valve after the 6 months study follow-up period and 30 out of 32 patients opted for the endobronchial valve treatment. The authors concluded that the endobronchial valve therapy resulted in clinically meaningful benefits in lung function, dyspnea, exercise tolerance and quality of life with an acceptable safety profile.

It is notable that the authors included only selected patients, limited to those with presence of heterogeneous emphysema, absence of collateral ventilation, low risk of COPD exacerbation or infection, and patients who were likely able to tolerate pneumothorax. Despite this, 13 patients developed pneumothorax and death occurred in 1 patient, leading to a significantly longer average length of hospital stay in the treatment group. Although this rate of complications is not higher than prior endobronchial valve studies, it is important to note when broadly applying the outcomes of this study to patient care. Lack of long-term follow-up and the nonblinded study design also limit the strength of this study.

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