Can the Number of Radiofrequency Activations Predict Serious Adverse Events after Bronchial Thermoplasty? A Retrospective Case-Control Study.

INTRODUCTION: Bronchial thermoplasty (BT) is a bronchoscopic procedure that involves the delivery of thermal radiofrequency energy to the bronchial wall for treating severe asthma. It has been suggested that too many radiofrequency activations could induce serious adverse events (SAEs) at an early stage. We aimed to examine the number of radiofrequency activations at each session and early lung function changes from baseline to determine whether these are related to SAEs. METHODS: We retrospectively investigated 13 consecutive patients who underwent three sessions each of BT for severe asthma from February 2015 to January 2016. Lung function tests were performed on the day before and after each BT procedure. Since we compared the number of activations and lung function changes from baseline after each session, a total of 39 sessions were reviewed. The relationship between the number of radiofrequency activations and each lung function change from baseline was also examined by linear regression analysis. RESULTS: A total of 10 SAEs (4 of pneumonia, 3 of atelectasis, 2 of bronchial asthma exacerbation and 1 of hemoptysis) were observed following the 39 BT sessions. When we compared sessions with and without SAEs, there were no differences in the number of activations (mean ± SD, 71.5 ± 28.6 times in sessions with SAEs; 66.5 ± 25.1 times in sessions without SAEs; p = 0.772) and lung function changes (mean changes in FVC/%FVC/FEV1/%FEV1/%PEF from baseline; - 0.49 l/- 14.2%/- 0.36 l/- 11.7%/- 9.6% in sessions with SAEs; - 0.43 l/- 13.3%/- 0.34 l/- 12.1%/- 9.4% in sessions without SAEs; p > 0.05 for all the above). Increase in the number of activations correlated with decreased FEV1 (R2 = 0.17, p = 0.0088) and %FEV1 (R2 = 0.11, p = 0.0357). CONCLUSIONS: Increase in the number of radiofrequency activations during BT is related to a decrease in FEV1 and %FEV1 from baseline. The number of radiofrequency activations, however, is not associated with SAEs after BT.