Langton D, et al. - The most common adverse effect of bronchial thermoplasty (BT) is short-term aggravation of asthma immediately following the procedure. In this current investigation, it was noted that post-BT deterioration in lung function in patients with very severe asthma was transient and well tolerated. However, it was greatest following upper lobe treatment and was significantly associated with the number of radiofrequency activations applied.