According to initial post-market surveillance registry results the Zenith Renu AAA Ancillary Graft System (Cook) appears to be a versatile and potentially durable solution when used for aortic endograft fixation failure. The Zenith Renu AAA graft system was developed specifically as an endovascular ‘bail-out’ option to treat proximal endograft fixation failure. Proximal endograft fixation failure leads to migration, Type I endoleak, and aneurysm rupture, with mortality rates for secondary open conversion after endovascular repair reported at 23%.
“One of the most serious long-term complications is device migration caused when a stent ‘slips’ downward within the aorta, which can result in an endoleak and ultimately can lead to a devastating aneurysm rupture,” said Dr Krishna Mannava, lead author and vascular surgical fellow at the Ochsner Clinic Foundation in New Orleans, LA. “One theory as to why this complication occurs is thought to be weakness in the attachment of the proximal portion of the graft to the inside of the aortic wall.”
Between September and December 2005, 65 Renu devices were implanted at multiple US institutions to treat failing endografts. An FDA mandated post-market registry has to date collected data for 44 Renu devices implanted at 32 institutions. The results show that 77.3% (34/44) of previously placed grafts were treated with converters while 22.7% (10/44) were treated with main body extensions. In total, six endovascular graft types were treated. The results showed that one open conversion and death occurred during Renu implantation secondary to aortic perforation, resulting in a procedure-related mortality and conversion rate of 2.3%. At last follow up, five patients treated with the Renu device continued to have proximal fixation failure. One new Type I endoleak developed during Renu implantation.
“At last follow-up, very few cases of persistent proximal fixation failure were reported,” noted Mannava. “Our preliminary evaluation of data suggests that patients with favourable aortic neck anatomy may be less susceptible to persistent proximal failure after treatment with the Renu system than patients with a challenging neck anatomy such as a conical neck shape, a short aortic seal length, or severe angulation.”
Early registry data suggest that the Renu device may be used to successfully treat proximal endograft fixation failure in most patients, particularly in ‘bail-out’ situations for poor surgical candidates. The mean time to treatment in this cohort was 3.6 years, demonstrating the late development of proximal endograft fixation failure and underscoring the need for vigilant surveillance of these patients. This registry is ongoing and further analysis with longer-term follow up is necessary, the researchers added.
Separately, patient enrolment has been completed in the STARZ-TX2 clinical trial (Study of Thoracic Aortic Aneurysm [TAA] Repair with the Zenith TX2 Thoracic TAA Endovascular Graft) and data submission to the FDA is been prepared for later this year.
The STARZ-TX2 trial, which enrolled more than 200 patients at 39 clinical sites around the world, studied the safety and effectiveness the Zenith TX2 for the treatment of thoracic aortic aneurysms. The primary hypothesis for effectiveness, according to Cook, is that patients treated with the Zenith TX2 TAA will have equivalent 30-day rupture-free survival compared to the surgical control. A secondary hypothesis is subjects treated with the Zenith TX2 TAA will have equivalent or fewer complications compared to the surgical control group through 30 days following implant.
All patients enrolled in the STARZ-TX2 trial are being evaluated at regular intervals during the 12 months following either insertion of the Zenith TX2 or open surgery.
While the Zenith TX2 is not yet approved for commercial use in the US, it is approved for sale in Europe, Australia, Brazil, Thailand, Singapore, Argentina, Peru, Mexico, Columbia and New Zealand. Several thousand patients have been treated outside the US for the past six years with the Zenith TX2 Thoracic TAA Endovascular Graft.