Purpose: The safety and efficacy of the Zenith (Cook Inc, Bloomington, Ind) endovascular graft was assessed based on the United States multicenter trial through 5 years of follow-up.
Methods: Between 2000 and 2003, the pivotal study enrolled patients to open surgery (control) or the Zenith endovascular graft (endovascular). A separate continued access study arm enrolled endovascular patients using the same inclusion/exclusion criteria. Both studies were designed for 2-year follow-up, and the pivotal endovascular patients had the option of extending the study follow-up through 5 years. All endovascular patients were stratified by physiologic risk into high-risk and standard-risk groups to assess overall mortality, rupture, conversion, endoleaks, secondary interventions, and sac enlargement. The entire endovascular cohort was pooled to assess device integrity, limb occlusion, component separation, and migration. The suboptimal endovascular result (SER) was established as an end point to assess late adverse outcomes. Statistical analyses included Kaplan-Meier estimations and Cox regression to assess factors contributing to sac enlargement and SER.
Results: The study enrolled 739 endovascular patients (352 pivotal, 387 continued access); 158 patients in the pivotal study reconsented to be followed up for 5 years. For the patients at standard and high risk at 5 years, the respective survival estimate was 83% and 61%, aneurysm-related death was 2% and 4%, and freedom from rupture was 100% and 99.6%, respectively. Cumulative risk of conversion, limb occlusion, migration >10 mm, or component separation was < or =3% at 5 years. Cumulative risk of late endoleak was 12% to 15%, representing the primary indication for secondary interventions which occurred in 20% of standard-risk patients and 25% of high-risk patients through 5 years. Sac enlargement was very rare and associated with advanced age and larger aneurysms. SER was predicted by advanced age and internal iliac artery occlusion.
Conclusion: These middle- and long-term data support long-term durability of the Zenith endovascular graft. Risk of aneurysm-related death or rupture was exceptionally low, and complications of migration, limb occlusion, and device integrity issues were uncommon. Incidence of late endoleaks and association of endoleaks with sac growth underscore the need for long-term follow-up of patients treated with endovascular grafts, although the sequelae of such events are unknown.