Although there are many possible triggers, an acute asthma attack is usually characterized by contraction of the smooth muscle in the airway wall. Bronchial thermoplasty, a novel bronchoscopic treatment approach, aims to reduce smooth muscle contraction as a potential therapy for asthma.
We studied the safety of bronchial thermoplasty with the Alair System in 16 subjects with a range of asthma severity. Accessible airways distal to main bronchi and 3mm in diameter or greater were treated. Baseline and 12-week post treatment measurements included spirometry, methacholine challenge, and daily diary recording of peak flow, symptoms and rescue medication usage. The diary was maintained through 12 weeks. Objective measures of lung function were performed at subsequent annual visits. A patient survey designed to retrospectively assess the patient’s quality of life and satisfaction was administered after the one-year follow-up visit.
Each patient was treated with approximately 120 total activations performed during three or four 30-minute treatment sessions. Side effects of the procedure were transient and typical of the types expected following bronchoscopy in patients with asthma. At 12 weeks, symptom-free days (p=0.012) and peak flow measurements (p<0.010) were improved over baseline. All patients had improvements in PC20 over baseline; the mean increase was 2.4 doubling doses (p<0.001). For the patients tested, PC20 values at the yearly follow-up demonstrated persistence of improvement over baseline out to 2 years. The patient survey was administered 14 to 36 months after the last treatment session. Seventy-five percent (75%) of patients believed they were less limited in their daily activities than they were before treatment; 25% believed they experienced no change. All 16 patients indicated that they would probably or definitely undergo the procedure again and would recommend the procedure to a friend or family member.
This experience suggests that bronchial thermoplasty is well tolerated in selected subjects with asthma with follow-up to beyond one year.
The efficacy of this procedure remains to be established through further controlled studies.
G. Cox, Asthmatx Inc.