Nature, frequency, and predictors of secondary procedures after endovascular repair of abdominal aortic aneurysm.

OBJECTIVES: Endovascular stent grafting offers a potentially less invasive option for treatment of abdominal aortic aneurysm. Clinical benefit has been demonstrated with respect to early parameters such as blood transfusion, return of gastrointestinal function, and length of hospital stay. Endovascular repair, however, has been criticized on the basis of inferior long-term outcome. Secondary procedures may be necessary to address durability issues such as migration, high-pressure endoleak, graft limb thrombosis, and degeneration of the stent-fabric structure itself, issues that may compromise the primary goal of aneurysm repair, protection from rupture.
METHODS: Between 1996 and 2002, 703 patients underwent endovascular treatment of infrarenal abdominal aortic aneurysm at The Cleveland Clinic Foundation. During this time, five devices were used: Ancure, AneuRx, Excluder, Talent, and Zenith. Outcome was assessed with physical examination, lower extremity arterial studies, plain abdominal radiography, and computed tomography at discharge, at 1, 6, and 12 months postoperatively, and annually thereafter. Secondary procedures were defined as any procedure, exclusive of diagnostic angiography, performed after stent graft implantation, directed at treatment of aneurysm-related events. Multivariable statistical techniques for censored data (Cox proportional hazards modeling) were used to determine baseline parameters associated with need for secondary procedures over follow-up, with calculation of hazards ratio (HR) and 95% confidence interval (CI).
RESULTS: Patient follow-up averaged 12.2 +/- 11.7 months. Patient survival was 90% +/- 1.4% at 1 year, 78% +/- 2.6% at 2 years, and 70% +/- 3.8% at 3 years. Aneurysm rupture occurred in 3 patients (0.4%), accounting for rupture risk of 1.4% over the first 2 years of follow-up (Kaplan-Meier method). Overall, 128 secondary procedures were required in 104 patients (15%), with a cumulative risk of 12% +/- 1.5% at 1 year, 24% +/- 2.8% at 2 years, and 35% +/- 4.4% at 3 years after stent graft implantation. Among the secondary procedures, new stent grafts and extensions were placed in 34 patients (27%), embolization of endoleak was performed in 33 patients (26%), and open surgical conversion was undertaken in 11 patients (9%). Periprocedural mortality of secondary procedures was 8% overall, but was 18% for patients undergoing open surgical conversion. Multivariable modeling identified the date the procedure was performed (HR, 1.53 per 3-month period of study; CI, 1.22-1.92; P <.001) and aneurysm size (HR, 1.35 per centimeter of minor axis; CI, 1.13-1.60; P <.001) as independent predictors of need for secondary procedures.
CONCLUSIONS: Current endovascular devices are associated with a relatively high rate of complications over mid-term follow-up, culminating in frequent need for secondary remedial procedures. With strict follow-up imaging compliance, however, risk for rupture and aneurysm-related death remain exceedingly low. Newer technology may achieve improved durability and a lower requirement for secondary procedures, while maintaining the minimally invasive nature of presently available devices.