Use of Quantitative CT Imaging to Identify Bronchial Thermoplasty Responders

BACKGROUND

Bronchial thermoplasty (BT) is a treatment for patients with poorly controlled, severe asthma. However, predictors of treatment response to BT are defined poorly.

RESEARCH QUESTION

Do baseline radiographic and clinical characteristics exist that predict response to BT?

STUDY DESIGN AND METHODS

We conducted a longitudinal prospective cohort study of participants with severe asthma receiving BT across eight academic medical centers. Participants received three separate BT treatments and were monitored at 3-month intervals for 1 year after BT. Similar to prior studies, a positive response to BT was defined as either improvement in Asthma Control Test results of ≥ 3 or Asthma Quality of Life Questionnaire of ≥ 0.5. Regression analyses were used to evaluate the association between pretreatment clinical and quantitative CT scan measures with subsequent BT response.

RESULTS

From 2006 through 2017, 88 participants received BT, with 70 participants (79.5%) identified as responders by Asthma Control Test or Asthma Quality of Life Questionnaire criteria. Responders were less likely to undergo an asthma-related ICU admission in the prior year (3% vs 25%; P = .01). On baseline quantitative CT imaging, BT responders showed less air trapping percentage (OR, 0.90; 95% CI, 0.82-0.99; P = .03), a greater Jacobian determinant (OR, 1.49; 95% CI, 1.05-2.11), greater SD of the Jacobian determinant (OR, 1.84; 95% CI, 1.04-3.26), and greater anisotropic deformation index (OR, 3.06; 95% CI, 1.06-8.86).

INTERPRETATION

To our knowledge, this is the largest study to evaluate baseline quantitative CT imaging and clinical characteristics associated with BT response. Our results show that preservation of normal lung expansion, indicated by less air trapping, a greater magnitude of isotropic expansion, and greater within-lung spatial variation on quantitative CT imaging, were predictors of future BT response.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01185275; URL: www.

CLINICALTRIALS

gov.

129Xe MRI and Oscillometry of Irritant-Induced Asthma After Bronchial Thermoplasty

Irritant-induced asthma (IIA) may develop after acute inhalational exposure in individuals without preexisting asthma. The effect of bronchial thermoplasty to treat intractable, worsening IIA has not yet been described. We evaluated a previously healthy 52-year-old man after inhalation of an unknown white powder. His pulmonary function and symptoms/quality of life worsened over 4 years, despite maximal guidelines-based asthma therapy. We acquired 129Xe MRI and pulmonary function test measurements on three occasions including before and after bronchial thermoplasty treatment. Seven months after bronchial thermoplasty, improved MRI ventilation and oscillometry small airway resistance were observed. Spirometry and asthma control did not improve until 19 months after bronchial thermoplasty, 5.5 years postexposure. Together, oscillometry measurements of the small airways and 129Xe MRI provided effort-independent, sensitive, and objective measurements of response to therapy. Improved MRI and oscillometry small airway resistance measurements temporally preceded improved airflow obstruction and may be considered for complex asthma cases.

Safety and efficacy of bronchial thermoplasty in Australia 5 years post-procedure

BACKGROUND AND OBJECTIVE

Outside clinical trials, there is limited long-term data following bronchial thermoplasty (BT). In a cohort of real-world severe asthmatics in an era of biological therapy, we sought to evaluate the safety and efficacy of BT 5 years post-treatment.

METHODS

Every patient treated with BT at two Australian tertiary centres were recalled at 5 years, and evaluated by interview and record review, Asthma Control Questionnaire (ACQ), spirometry and high-resolution CT Chest. CT scans were interpreted using the modified Reiff and BRICS CT scoring systems for bronchiectasis.

RESULTS

Fifty-one patients were evaluated. At baseline, this cohort had a mean age of 59.0 ± 11.8 years, mean ACQ of 3.0 ± 1.0, mean FEV1 of 55.5 ± 18.8% predicted, and 53% were receiving maintenance oral steroids in addition to triple inhaler therapy. At 5 years, there was a sustained improvement in ACQ scores to 1.8 ± 1.0 (p < 0.001). Steroid requiring exacerbation frequency was reduced from 3.8 ± 3.6 to 1.0 ± 1.6 exacerbations per annum (p < 0.001). 44% of patients had been weaned off oral steroids. No change in spirometry was observed. CT scanning identified minor degrees of localized radiological bronchiectasis in 23/47 patients with the modified Reiff score increasing from 0.6 ± 2.6 at baseline to 1.3 ± 2.5 (p < 0.001). However, no patients exhibited clinical features of bronchiectasis, such as recurrent bacterial infection.

CONCLUSION

Sustained clinical benefit from BT at 5 years was demonstrated in this cohort of very severe asthmatics. Mild, localized radiological bronchiectasis was identified in a portion of patients without clinical features of bronchiectasis.

The efficacy and safety of bronchial thermoplasty in severe persistent asthma on extended follow-up

BACKGROUND

Asthma is a common condition and there remains a subset of patients who are poorly controlled on maximal therapy. Bronchial thermoplasty (BT) is a bronchoscopic therapy using radiofrequency energy to reduce airway smooth muscle, which has been shown to improve asthma control although further evidence regarding long-term efficacy and safety is required.

AIM

We aimed to demonstrate safety and efficacy of BT on extended follow-up. Our initial experience with this group was previously reported in 2016, where patients were shown to have a significant improvement in asthma control test (ACT) scores 1-year post-treatment.

DESIGN

We carried out a retrospective observational study of seven patients who underwent BT between 2012 and 2013 in an Irish severe asthma centre. The primary endpoint was change in ACT scores from baseline to present.

METHODS

Seven patients underwent BT at a tertiary referral centre in Ireland. ACT scores and data on hospital admissions, exacerbations, maintenance corticosteroid requirements, rescue bronchodilator use and forced expiratory volume for 1 s (FEV1) prior to the procedure and on extended follow-up were collected. Mean follow-up was 49.42 months.

RESULTS

A trend towards improvement was seen in median hospitalisations (respective values for median over 12 months 3, 1 P = 0.059) and ACT scores, from 9 to 13 (P = 0.249). Mean FEV1 was 1.68 l prior to treatment and 1.46 l 4 years post-treatment (P = 0.237). There was no mortality among the group.

CONCLUSIONS

These data support the safety of BT and suggest extended efficacy.