Incidence and Predictors of Sac Enlargement after Endovascular Repair of Abdominal Aortic Aneurysms
Gregory Tsougranis, BS, Thomas FX O'Donnell, MD, Emel Ergul, MS, W. Darrin Clouse, MD, Mark F. Conrad, MD.
Massachusetts General Hospital, Boston, MA, USA.
OBJECTIVES: A large multicenter observational study of patients undergoing endovascular repair of abdominal aortic aneurysms (EVAR) found that 30-60% of patients are treated outside the instructions for use (IFU) with an associated sac enlargement of 41% at 5 years. These results seemed high so we sought to document the incidence and predictors of sac enlargement after EVAR in a large single center experience with long-term follow-up.
METHODS: All patients who underwent infrarenal EVAR at a single institution between 1999-2009 were identified. Patients with pre-operative and at least 1 post-operative axial imaging study were included. Aortic characteristics were characterized by two reviewers, and change in maximum sac diameter was followed over time. A >5mm change was used to define sac enlargement or shrinkage. Demographic and anatomic predictors of sac change were evaluated with multivariate analysis.
RESULTS: We identified 772 EVAR during the study period. 80% were male,76% had hypertension and 25% had COPD. If liberal IFU parameters were used, 117 (23%) patients were treated outside the IFU and 51% met conservative IFU parameters. The most common violation was neck angle >45 in 171 (38%) followed by proximal seal zone <15mm in 83 (17%). Sac enlargement was seen in 92 (12%) patients and shrinkage was seen in 347 (42%) patients. The remaining 333 (40%) showed no change over time. Endoleaks were present in 33% of patients; most (83%) were type II. The only predictor of sac growth was persistent endoleak.
CONCLUSIONS: Sac growth after EVAR was much rarer in this study than frequently reported and was driven by the presence of a persistent endoleak. Although 23% of patients were treated outside of the liberal IFU parameters, no individual violation was predictive of sac growth.
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