Changes in dynamic lung mechanics after lung volume reduction coil treatment of severe emphysema

Identifying Responders and Exploring Mechanisms of Action of the Endobronchial Coil Treatment for Emphysema

BACKGROUND

So far, 3 randomized controlled trials have shown that the endobronchial treatment using coils is safe and effective. However, the more exact underlying mechanism of the treatment and best predictors of response are unknown.

OBJECTIVES

The aim of the study was to gain more knowledge about the underlying physiological mechanism of the lung volume reduction coil treatment and to identify potential predictors of response to this treatment.

METHODS

This was a prospective nonrandomized single-center study which included patients who were bilaterally treated with coils. Patients underwent an extensive number of physical tests at baseline and 3 months after treatment.

RESULTS

Twenty-four patients (29% male, mean age 62 years, forced expiratory volume in 1 s [FEV1] 26% pred, residual volume (RV) 231% pred) were included. Three months after treatment, significant improvements were found in spirometry, static hyperinflation, air trapping, airway resistance, treated lobe RV and treated lobes air trapping measured on CT scan, exercise capacity, and quality of life. The change in RV and airway resistance was significantly associated with a change in FEV1, forced vital capacity, air trapping, maximal expiratory pressure, dynamic compliance, and dynamic hyperinflation. Predictors of treatment response at baseline were a higher RV, larger air trapping, higher emphysema score in the treated lobes, and a lower physical activity level.

CONCLUSIONS

Our results confirm that emphysema patients benefit from endobronchial coil treatment. The primary mechanism of action is decreasing static hyperinflation with improvement of airway resistance which consequently changes dynamic lung mechanics. However, the right patient population needs to be selected for the treatment to be beneficial which should include patients with severe lung hyperinflation, severe air trapping, and significant emphysema in target lobes.

Change in Dynamic Hyperinflation After Bronchoscopic Lung Volume Reduction in Patients with Emphysema

BACKGROUND AND PURPOSE

In patients with severe emphysema, dynamic hyperinflation is superimposed on top of already existing static hyperinflation. Static hyperinflation reduces significantly after bronchoscopic lung volume reduction (BLVR). In this study, we investigated the effect of BLVR compared to standard of care (SoC) on dynamic hyperinflation.

METHODS

Dynamic hyperinflation was induced by a manually paced tachypnea test (MPT) and was defined by change in inspiratory capacity (IC) measured before and after MPT. Static and dynamic hyperinflation measurements were performed both at baseline and 6 months after BLVR with endobronchial valves or coils (treatment group) or SoC (control group).

RESULTS

Eighteen patients underwent BLVR (78% female, 57 (43-67) years, FEV₁ 25(18-37) %predicted, residual volume 231 (182-376) %predicted). Thirteen patients received SoC (100% female, 59 (44-74) years, FEV₁ 25 (19-37) %predicted, residual volume 225 (152-279) %predicted. The 6 months median change in dynamic hyperinflation in the treatment group was: + 225 ml (range - 113 to + 803) (p < 0.01) vs 0 ml (- 1067 to + 500) in the control group (p = 0.422). An increase in dynamic hyperinflation was significantly associated with a decrease in residual volume (r = - 0.439, p < 0.01).

CONCLUSION

Bronchoscopic lung volume reduction increases the ability for dynamic hyperinflation in patients with severe emphysema. We propose this is a consequence of improved static hyperinflation.

Endobronchial coils for emphysema: Dual mechanism of action on lobar residual volume reduction

BACKGROUND AND OBJECTIVE

The RENEW trial demonstrated that bronchoscopic lung volume reduction using endobronchial coils improves quality of life, pulmonary function and exercise performance. In this post hoc analysis of RENEW, we examine the mechanism of action of endobronchial coils that drives improvement in clinical outcomes.

METHODS

A total of 78 patients from the RENEW coil-treated group who were treated in one or both lobes that were deemed as the most destroyed were included in this retrospective analysis. Expiratory and inspiratory HRCT scans were used to assess lobar volume change from baseline to 12 months post coil treatment in treated and untreated lobes.

RESULTS

Reduction in lobar RV in treated lobes was significantly associated with favourable clinical improvement. Independent predictor of the change in RV and FEV₁ was the change in lobar RV reduction in the treated lobes and for change in 6MWD the absence of cardiac disease and the change in SGRQ, while the independent predictor of change in SGRQ was the change in 6MWD.

CONCLUSION

Our results suggest that residual lobar volume reduction in treated lobes measured by QCT is the driving mechanism of action of endobronchial coils leading to positive clinical outcomes. However, the improvement in exercise capacity and quality of life seems to be affected by the presence of cardiac disease.

Protocol of a Randomized Controlled Study of the PneumRx Endobronchial Coil System versus Standard-of-Care Medical Management in the Treatment of Subjects with Severe Emphysema (ELEVATE)

BACKGROUND

The PneumRx endobronchial coil system for patients with severe emphysema has been shown to improve quality of life, exercise capacity, and pulmonary function in patients with emphysema. A post hoc analysis of the RENEW trial has identified patient characteristics and lobar selection methods associated with improved outcomes, which have to be confirmed prospectively.

METHODS

The ELEVATE trial is a prospective, multicenter, open label, randomized (2:1), controlled trial comparing outcomes in patients treated with endobronchial coils (treatment) to a medically managed control group (control). The trial aims to enroll 210 patients (140 in the treatment group and 70 in the control group) with severe emphysema. Control patients will be eligible to crossover to coil treatment after 6 months of follow-up. The co-primary effectiveness endpoints are percent change in forced expiratory volume in 1 s and quality of life measured by change in St. George's Respiratory Questionnaire from baseline to 6 months. Secondary objectives are determination of responder rates of clinical endpoints and mean change in other functional and physiologic endpoints. All patients will be followed for 24 months after initial treatment. Adverse events will be collected on an ongoing basis throughout the trial.

DISCUSSION

The primary objective of the ELEVATE trial is to prospectively confirm the safety and effectiveness profile of the coil system for the treatment of severe emphysema in consideration of the findings of previous randomized controlled trials. Secondary objectives are the determination of responder rates in all clinical endpoints and mean change in physiologic endpoints.

Predictors of Response to Endobronchial Coil Therapy in Patients With Advanced Emphysema

BACKGROUND

The Lung Volume Reduction Coil Treatment in Patients With Emphysema (RENEW) trial reported improvements in quality of life, pulmonary function, and exercise performance following endobronchial coil treatment.

OBJECTIVES

The purpose of this post hoc analysis was to identify baseline predictors, including quantitative CT measures, that identify patients most likely to significantly benefit from endobronchial coil therapy.

METHODS

Quantitative CT analysis by an independent radiology laboratory and a qualitative evaluation by five blinded experts of the baseline thoracic CT imaging were performed. Univariate and multivariate logistic regression analyses were performed to elucidate characteristics associated with clinical response.

RESULTS

In total, 125 patients underwent coil treatment and had evaluable 12-month follow-up results. Of these, 78 patients received treatment of lobes with the highest emphysematous destruction determined by quantitative CT analysis (quantitative visual match [QVM]+), and 47 received treatment in at least one lobe that was not the most destroyed (QVM-). From the 78 patients with QVM+ treatment, a subgroup of 50 patients (64%) was identified with baseline residual volume > 200% predicted, emphysema score > 20% low attenuation area, and absence of airway disease. In this subgroup, greater lobar residual volume reduction in the treated lobes was achieved, which was associated with significant mean ± SE improvement in FEV₁ (15.2 ± 3.1%), St. George's Respiratory Questionnaire (-12 ± 2 points), and residual volume (-0.57 ± 0.13 L).

DISCUSSION

This post hoc analysis found that both significant hyperinflation (residual volume ≥ 200% predicted) and CT analysis are critical for patient selection and treatment planning for endobronchial coil therapy. Quantitative CT analysis is important to identify optimal lobar treatment and to exclude patients with insufficient emphysema (< 20% low attenuation area), whereas visual assessment identifies patients with signs of airway disease associated with worse outcomes.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01608490; URL: www.clinicaltrials.gov.

Cost-effectiveness of lung volume reduction coil treatment in patients with severe emphysema: results from the 2-year follow-up crossover REVOLENS study (REVOLENS-2 study)

BACKGROUND

The REVOLENS study compared lung volume reduction coil treatment to usual care in patients with severe emphysema at 1 year, resulting in improved quality-adjusted life-year (QALY) and higher costs. Durability of the coil treatment benefit and its cost-effectiveness at 2 years are now assessed.

METHODS

After one year, the REVOLENS trial's usual care group patients received coil treatment (second-line coil treatment group). Costs and QALYs were assessed in both arms at 2 years and an incremental cost-effectiveness ratio in cost per QALY gained was calculated. The uncertainty of the results was estimated by probabilistic bootstrapping.

RESULTS

The average cost of coil treatment in both groups was estimated at €24,356. The average total cost at 2 years was €9655 higher in the first-line coil treatment group (p = 0.07) and the difference in QALY between the two groups was 0.127 (p = 0.12) in favor of first-line coil treatment group. The 2-year incremental cost-effectiveness ratio (ICER) was €75,978 / QALY. The scatter plot of the probabilistic bootstrapping had 92% of the replications in the top right-hand quadrant.

CONCLUSION

First-line coil treatment was more expensive but also more effective than second-line coil treatment at 2 years, with a 2-year ICER of €75,978 / QALY.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT01822795 .

Bronchoscopic lung volume reduction: recent updates

Emphysema causes significant morbidity and mortality, incurring both financial and psychosocial costs. Alternatives to medical therapy and surgical lung volume reduction surgery (LVRS) have increased interest in bronchoscopic techniques. Bronchoscopic lung volume reduction (BLVR) is still in its infancy and additional trials and follow-up are critical. However, several new randomized clinical trials (RCTs) have demonstrated improvement in lung function, quality of life and exercise capacity in select patients receiving endobronchial valves and coil therapy. This article highlights recent data regarding bronchoscopic treatment of emphysema.