Initial results from a US study with the Valiant thoracic stent graft system (Medtronic) demonstrate early safety and effectiveness for the treatment of thoracic aortic aneurysms. The data were presented at the VEITHsymposium, in New York, USA.
Approved by the FDA under an investigational device exemption (IDE), the prospective, single-arm study involved 160 patients at 24 US medical centres. Called VALOR II, the study was designed to evaluate the safety and effectiveness of the Valiant device for thoracic endovascular aortic repair (TEVAR) for aneurysms in the descending thoracic aorta.
Through 30 days of follow up in VALOR II, rates of site-reported endoleaks were low: 0.7% for type I, 3.4% for type II, and zero percent for both type III and IV. In addition, no patients’ treatment plans were converted from TEVAR to open surgery, and no patients experienced aneurysm rupture. The rate of all-cause mortality through 30 days was 3.1%.
“These compelling interim data from VALOR II show great promise for the Valiant thoracic stent graft,” said the study’s principal investigator, Ronald Fairman, professor of surgery and chief of the division of vascular surgery and endovascular therapy at the Hospital of the University of Pennsylvania. “We look forward to seeing whether these results persist at the primary endpoint of 12 months and supply the evidence needed so that clinicians in the United States can use the Valiant stent graft in their practice.”
The study’s primary safety and effectiveness endpoints are 12-month all-cause mortality and 12-month successful aneurysm treatment, defined as the absence of aneurysm growth (>5mm) at one and 12 months and type I and/or type III endoleak for which a secondary procedure was performed or recommended at or before the 12 month visit. The one-year results of VALOR II will be presented in mid-2011, along with unprecedented five-year TEVAR data from VALOR.
The Valiant device differs from the Talent thoracic stent graft in several ways:
- The Valiant graft is a modular device consisting of a polyester graft sutured to the outside (as opposed to the inside on Talent) of a self-expanding nitinol wire stent comprised of eight peaked springs stacked in a tubular configuration. With an outside suture, the raised surface of the springs provides additional mechanical interference when apposing to the aortic wall for improved sealing and fixation.
- The proximal and distal stent has an eight-peak crown (as compared to the five-peak configuration of Talent) that distributes radial force across more points of contact allowing for excellent sealing characteristics and a softer interface with the aortic wall.
- To increase graft flexibility and conformability, the longitudinal connecting bar of Talent has been eliminated in Valiant, and the spring spacing has been redesigned to allow adjacent peaks to contact each other and provide the necessary column strength for deployment.
The Valiant device is currently used to treat patients with thoracic aortic aneurysms and injuries in more than 90 countries around the world. The leading thoracic stent graft outside the United States, it received the CE mark in October 2009. The Valiant stent graft System is an investigational device in the United States, where its clinical use is limited to studies approved by the FDA. VALOR II data will be used in Medtronic’s submission to the FDA for pre-market approval (PMA) of the Valiant stent graft.