SALT LAKE CITY Oct 26 (Reuters) The removal of muscle tissue in the hyperactive airways of asthma patients by exposing the tissue to heat reduces disease exacerbations and significantly improves the patients' quality of life, Canadian investigators announced here during CHEST 2006, the annual meeting of the American College of Chest Physicians.
The Asthma Intervention Research trial involved 108 patients, who were an average of 39.4 years old, with poorly controlled moderate-to-severe asthma. The subjects' asthma persisted despite optimal drug therapy with corticosteroids and long-acting beta-agonists.
At study entry, the patients had FEV1 levels between 60 and 80 percent of normal. FEV1 (forced expiration volume in 1 second) is a test commonly used to assess lung function.
Dr Michel Laviolette of Laval University in Sainte-Foy, Quebec, and colleagues across Canada randomly assigned the patients to continue drug treatment (the control group) or to undergo bronchial thermoplasty, in which a catheter with a thermal energy tip is used to reduce smooth muscle mass in all accessible airways. Thermoplasty was performed in three 30-minute sessions, with approximately 45 activations delivered during each session.
Patients were evaluated 3, 6, and 12 months after thermoplasty.
FEV1 was measured at each evaluation. Patients also refrained from using long-acting beta-agonists for two weeks before each assessment to destabilize disease ''and capture true disease activity and get a better assessment of the efficacy of thermoplasty,'' Laviolette explained.
There was a 50-per cent reduction in exacerbation rates in the thermoplasty group compared with the controls, Laviolette announced. The need for asthma medication was also significantly reduced and quality of life scores were significantly higher in thermoplasty patients.
''There was a significant change in disease exacerbation in thermoplasty patients. There was no change or a worsening of exacerbations in controls,'' he said. ''The change in quality of life was really clinically significant.'' Adverse effects with thermoplasty typically include a worsening of asthma symptoms within a day after the procedure, but clearing within a few weeks.
''There was almost no smooth muscle left after thermoplasty,'' Laviolette reported while showing tissue slides of airways before and after the thermoplasty.
He said that animal studies of thermoplasty show that the positive changes in airways have persisted for at least three years so far.
''This is clearly one of the most original studies that I heard here,'' Dr Peter R Smith of Long Island College Hospital in Brooklyn, New York told Reuters Health. Smith participated in the discussion that followed Laviolette's presentation. ''As a pulmonologist in a tertiary care hospital, I am still faced with no other options in asthmatics on maximal (drug) therapy.'' REUTERS LL BST0931