NEW YORK (Reuters Health) – Cutting balloon (CB) therapy is effective and safe for pulmonary artery stenosis resistant to conventional angioplasty techniques, results of a randomized study suggest.
Cutting balloons have microsurgical blades mounted longitudinally on their outer surface. When the balloon is inflated, the blades score the vessel, creating initiation sites for vessel expansion with less pressure than conventional balloon angioplasty. Cutting balloons are marketed by Boston Scientific, which funded the current study.
“While widely available, cutting balloons are more expensive than most balloons without microsurgical blades so should be reserved for required therapy,” Dr. Lisa Bergersen of Children’s Hospital Boston, noted in an email to Reuters Health. “Children and adults with resistant obstruction would benefit most,” she said.
Pulmonary artery stenosis accounts for about 10% of heart defects diagnosed during childhood. It can occur in children with otherwise normal hearts or along with other congenital heart defects such as atrial septal defect or Tetralogy of Fallot.
Low-pressure or high-pressure balloon angioplasty is often used successfully to increase lumen diameter and improve pulmonary blood flow. Yet, a subset of vessels (about 30%) are resistant to conventional balloon techniques. For these vessels, off-label use of CB therapy has been reported to be effective although the risk profile is unclear.
Dr. Bergersen and her colleagues designed a prospective randomized trial to compare the safety and effectiveness of CB therapy with conventional high-pressure balloon (HBP) therapy in children with pulmonary artery stenosis resistant to low-pressure angioplasty.
They enrolled 73 children with pulmonary artery stenosis at eight centers. In these patients 72 of 245 stenotic vessels (29%) responded to low-pressure balloon dilation. Of the remaining 173 vessels, 107 were randomly assigned to CB therapy and 66 to HPB therapy.
CB therapy, the clinicians report, was associated with greater percent increase in lumen diameter (the primary efficacy outcome) than HPB therapy (85% vs 52%; P = 0.004). The absolute change in minimum lumen diameter was 1.3 mm for the CB group and 0.8 mm for the HPB therapy group.
Twenty-six vessels that crossed over to CB therapy after HBP therapy achieved further gains in lumen diameter. Among these crossover vessels, the mean initial lumen diameter measured 1.9 mm and increased to 2.6 mm after HBP therapy.
In some of these vessels, a final lumen diameter of 3.5 mm was achieved. In these vessels, percent change in lumen diameter after HBP therapy was 51% compared with 99% after CB, the investigators note.
The safety profiles for CB and HPB therapy “appear equivalent although the study was not powered to show a difference,” the investigators note. There were no serious adverse events in a study vessel in either treatment group.
There were 14 “somewhat serious” or “not serious” adverse events in the CB group; seven of these were pulmonary edema potentially due to reperfusion after a successful dilation and were classified as not serious in five. There were three “somewhat serious” or “not serious” adverse events in the HBP group; all three were pulmonary edema.
“Clinical studies to support device therapy in pediatrics requires unique study design alternatives, creative analytical techniques to overcome small sample sizes, and active multicenter collaboration and patient enrollment,” Dr. Bergersen commented.
“This study demonstrates the feasibility in the pediatric field of catheterization in congenital heart disease and is one of few emerging studies designed to specifically critically device technology in children,” she said.
Circulation 2011;124.
