Effect of type II endoleaks and antiplatelet therapy on abdominal aortic aneurysm shrinkage after endovascular repair

Objective: Endovascular repair of abdominal aortic aneurysm (EVAR) has been shown to be safe, and its use is increasing rapidly, but the long-term results of this procedure remain unclear. A decrease in the diameter of the aneurysm sac is considered to represent successful exclusion of the aneurysm from the circulation, but it has been reported that aneurysm shrinkage occurs in only about 60% of patients who have undergone EVAR. We analyzed several factors to determine whether they were related to aneurysm shrinkage after EVAR. Methods: From March 2007 to January 2010, EVAR was performed in 65 patients, 58 of whom underwent an enhanced computerized tomographic evaluation 6 months after the procedure. One patient was found to have a type Ia endoleak and was excluded from the study. In the remaining 57 patients, univariate and multiple regression analyses were used to determine whether there was a relationship between aneurysm shrinkage and various patient characteristics, aneurysm dimensions, and procedural outcomes. Aneurysm shrinkage was defined as a decrease in diameter of at least 4 mm. Results: On univariate analysis, a lack of aneurysm shrinkage by 7 days and 6 months after EVAR was significantly associated with hyperlipidemia, ongoing multiagent antiplatelet therapy with clopidogrel, ticlopidine, or cilostazol as well as aspirin, length of the proximal neck of the aneurysm, preprocedure maximum aneurysm diameter, and the presence of a type II endoleak. On multiple regression analysis, only multiagent antiplatelet therapy and type II endoleak were significantly related to a lack of aneurysm shrinkage 6 months after EVAR. Multiagent antiplatelet therapy and type II endoleak 6 months after EVAR were not significantly associated with each other. Conclusion: Patients with a persistent type II endoleak and patients undergoing multiagent antiplatelet therapy are at an increased risk of a lack of aneurysm shrinkage 6 months after EVAR.