Covered CP Stents for the Prevention or Treatment of Aortic Wall Injury Associated With Coarctation of the Aorta

Overview

Coarctation of the aorta (CoA) is a congenital abnormality producing obstruction to blood flow through the aorta. Coarctation can occur in isolation, in association with bicuspid aortic valve or with major cardiac malformations. CoA accounts for 5-8% of the 8/1000 (4-6/10,000) children born with congenital heart disease. Most CoA is newly diagnosed in childhood; \< 25% recognized beyond 10 yrs. CoA is mostly repaired in childhood by surgery or by balloon catheter dilation. Recurrence rates range from 5-20%. Recurrence is often not recognized until adolescence. Balloon expandable stents have become the predominant therapy in the USA and Europe for CoA treatment in this age group. There are no FDA approved stents for this use. Biliary stents are currently being used off label. Enrollment into a trial of bare metal Cheatham Platinum (CP) Stents, designed for use in CoA, is completed. The Coarctation of the Aorta Stent Trial (COAST) aims to confirm safety and efficacy of CP Stent for native and recurrent CoA. There are CoA patients with clinical situations that place them at high risk of aortic wall injury during bare metal stenting. Extreme narrowing, genetic aortic wall weakness and advanced age are examples. Patients may present with aortic wall injury (aneurysm) related to prior CoA repair. The occurrence after surgical repair is 3-4% and after balloon dilation 10-20%. Repair of these aneurysms is surgically challenging. The use of fabric-covered CP Stents to prevent or repair aortic wall injury has become the treatment of choice in Europe and recently in the US through the FDA Compassionate Use process. There are no alternative devices available in the US. COAST II will test safety and efficacy of Covered CP Stents to repair or prevent aortic wall injury associated with CoA. Funding Source-FDA OOPD

There are no prior trials of preventing or treating aortic injury associated with CoA and thus no basis for comparison. A single outcome assessment will not suffice since patients can receive a device for either indication. A 3-category Severity of Illness Scale (SIS) was developed based on clinical judgment of a panel of pediatric cardiologists and reviewed by a Data \& Safety Monitoring Board (DSMB) and the FDA Office of Device Evaluation. Five levels of severity have been defined for each of the 3 illness categories, including: Upper extremity hypertension, Upper to lower extremity pressure difference, and Severity of aortic wall injury. The DSMB will assign a level of illness from the SIS for each patient at baseline and one year follow up. Improvement by at least one level will indicate clinical importance. Safety is evaluated by identifying adverse events and comparing their occurrence to surgical repair of CoA in similar age groups reported in the medical literature.