Rationale: Bronchial thermoplasty (BT) reduces the potential for smooth muscle-mediated bronchoconstriction by reducing the mass of smooth muscle in the walls of conducting airways.
Objectives: This study was conducted to examine the safety and impact on lung function and airway responsiveness of BT over 2 yr.
Methods: The safety of BT was studied in 16 subjects with mild to moderate asthma. Baseline and 12-wk post-treatment measurements included spirometry, methacholine challenge, daily diary recordings of peak flow, symptoms, and medication usage. Subjects completed follow-up evaluations at 12 wk, 1 yr, and 2 yr.
Measurements and main results: The procedure was well tolerated; side effects were transient and typical of what is commonly observed after bronchoscopy. All subjects demonstrated improvement in airway responsiveness. The mean PC(20) increased by 2.37 +/- 1.72 (p < 0.001), 2.77 +/- 1.53 (p = 0.007), and 2.64 +/- 1.52 doublings (p < 0.001), at 12 wk, 1 yr, and 2 yr post-procedure, respectively. Data from daily diaries collected for 12 wk indicated significant improvements over baseline in symptom-free days (p = 0.015), morning peak flow (p = 0.01), and evening peak flow (p < or = 0.007). Spirometry measurements remained stable throughout the study period.
Conclusions: BT is well tolerated in patients with asthma and results in decreased airway hyperresponsiveness that persists for at least 2 yr.