Zenith AAA endovascular graft: intermediate-term results of the US multicenter trial

Abstract

Purpose: The intent of this study was to assess the safety and effectiveness of the Zenith AAA Endovascular Graft compared with conventional aneurysm repair.

Material and methods: The study was conducted in a prospective, multicenter, nonrandomized, concurrent control manner. Physiologically similar patients with infrarenal abdominal aortic aneurysms (AAAs) underwent either open surgery or repair with the Zenith AAA Endovascular Graft. Separate analyses of physiologically challenged patients were performed. Follow-up was conducted at hospital discharge and at 1, 6, and 12 months (endovascular repair group) or 1 and 12 months (open surgical repair group). Evaluation included computed tomography, abdominal radiography, laboratory tests, and physical examination. Mortality (AAA-related and overall), morbidity, in-hospital recovery, renal function, and secondary interventions were assessed. Patients in the endovascular repair group were evaluated for change in aneurysm size, endoleak, graft migration, conversion, rupture, and device integrity. Statistical analyses were performed with the Kaplan-Meier method, Blackwelder test, propensity score assessment, two-sample t test, Yates-corrected Pearson chi(2) test, and Fisher exact test.

Results: Conventional open surgery was used in 80 patients, and 200 patients underwent repair with the Zenith AAA Endovascular Graft. Technical success was accomplished in 98.8% of patients in the open repair group and 99.5% in the endovascular repair group. Patients in the endovascular repair group had fewer significant adverse events within 30 days (80% vs 57%; P <.001). All-cause mortality was similar (endovascular, 3.5%; open surgery, 3.8%). Aneurysm-related mortality was higher with conventional surgery at 12 months (3.8% vs 0.5%; P =.04). In-hospital recovery and procedural measures were better for endovascular repair in all categories (P <.001). The incidence of endoleak was 17% at 30 days, 7.4% at 12 months, and 5.4% at 24 months. Aneurysm shrinkage (>5 mm) was noted in more than two thirds of patients at 12 months and three fourths of patients at 24 months. Renal dysfunction rate did not differ between groups. Migration (>5 mm) was detected in four (2%) patients through 12 months; none was greater than 10 mm or associated with adverse events through 24 months. Three conversions were performed within 12 months, one because of aneurysm rupture. Secondary procedures were more common in the endovascular group (11% vs 2.5%; P =.03). In total, 351 patients had endografts implanted, and 6 patients were noted to have barb separations through 12-month follow-up. No stent fractures were noted.

Conclusions: The Zenith AAA Endovascular Graft is safe and effective for treatment of infrarenal AAAs. The high likelihood of decrease in aneurysm size provides evidence that treatment of aneurysms with this device reverses the natural history of aneurysmal disease. The importance of long-term follow-up is underscored by the small but defined incidence of barb separation and the potential for unforeseen failure modes.