July 3, 2008 - A multicenter trial with up to five years of follow-up continues to support the mid- and long-term durability and safety of the Zenith endovascular graft used for aneurysm repair.
“Our study showed that the risk of aneurysm-related death or rupture were exceptionally low, and complications of migration, limb occlusion and device integrity issues were uncommon,” said Roy Greenberg, M.D., director of endovascular research at The Cleveland Clinic Foundation.
Between 2000 and 2003, a 739 endovascular patients were enrolled in open surgery. Of these, 352 were in the pivotal (control) group and 287 were in the endovascular continued access group where the Zenith endovascular graft was implemented. Both studies were designed for two-year follow up; however 158 patients in the pivotal study re-consented to be followed for five years.
All endovascular patients were divided into both physiologic high-risk (HR) and standard-risk (SR) groups to assess overall mortality, rupture, conversion, endoleaks, secondary interventions and sac enlargement. The entire endovascular cohort was assessed for device integrity (determined by holes in the fabric, separation/fracture of barbs and fractures of z-stents), limb occlusion, component separation and migration. A suboptimal endovascular endpoint (SER) was established to assess the risk of late adverse outcomes.
For the patients at HR and SR at five years, the respective percentages included survival estimate was 83 percent and 61 percent; aneurysm-related death was 2 percent and 4 percent; and freedom from rupture was 100 percent and 99.6 percent. Cumulative risk of conversion, limb occlusion, migration more than 10 mm, or component separation was 3 percent or less for all patient groups.
Endoleak represented the most common indication for a secondary intervention, and the cumulative risk of late endoleak was 12 to 15 percent. Secondary interventions were performed in 20 percent of standard risk patients and 25 percent of high-risk patients followed through five years.
“This study, detailed in the July issue of the Journal of Vascular Surgery, found the long-term durability of the Zenith endovascular graft superior for patients amenable to open surgical repair as well as those considered to be at high physiological risk,” Dr. Greenberg said. “The lack of late ruptures, the small number of conversions and low risk of migration, limb thrombosis, component separation and stent fracture relate to the quality of implant construct and patient selection.”
Dr. Greenberg noted that in the study sac enlargement was very uncommon. Of the 31 patients who experienced sac enlargement, 25 were related to early or late endoleaks (80 percent of which were type II in nature), and definitive explanations for cause of sac enlargement was present for all but three patients. Predictors for sac size enlargement included advanced patient age and larger initial aneurysm size.
“Although we fully support the use of the Zenith endovascular graft, sac behavior and late endoleak incidence underscore the need of further investigation for long-term follow-up of patients treated with an endovascular graft,” said Dr. Greenberg.
For more information: www.jvascsurg.org, www.VascularWeb.org