BRIEF REPORT Delayed Intimal Blowout after Endovascular Repair of Aortic Dissection Anirudh Mirakhur, MD, Jehangir J. Appoo, MDCM, FRCSC, William Kent, MD, MSc, Eric J. Herget, MD, FRCPC, and Jason K. Wong, MD, FRCPC ABSTRACT The authors have seen four cases of asymptomatic delayed intimal injury adjacent to a stent graft diagnosed 7 to 16 months after thoracic endovascular aortic repair. Endovascular repeat intervention was successfully performed in three of the four cases as described in the present report. A second consecutive “intimal blowout” in one patient remains under close radiologic surveillance. Possible causes for the intimal blowouts, including stent-graft size, landing zone anatomy, and intrinsically weak aortic tissue, are discussed. ABBREVIATIONS AD = aortic dissection, TAA = thoracic aortic aneurysm, TEVAR = thoracic endovascular aortic repair Following the initial experience of Dake and colleagues (1) with stent-graft exclusion of thoracic aortic aneur- ysms (TAAs), thoracic endovascular aortic repair (TEVAR) has emerged as a viable treatment option for a broader spectrum of aortic disease. One such application is for patients with life-threatening compli- cations of acute type B dissection (2–4). However, the use of TEVAR for treatment of uncomplicated acute aortic dissection (AD) and chronic AD with aneurysmal degeneration remains controversial, as no clear survival benefit has been demonstrated despite favorable mor- phologic outcomes, with results of long-term follow-up still pending (3–7). An important determinant of the morphologic success of endovascular therapy for ADs is the nature of long-term remodeling changes that occur in the stent-implanted segment and adjacent native aorta. The mechanical forces associated with stent grafts and their effects on the adjacent aortic tissues, especially over the long term, are not yet fully understood (4–6). Formation of a new intimal tear with resultant pseudoaneurysm formation or dissection at the proximal or distal margin of the stent graft has been previously described in patients undergoing TEVAR for AD (7–12). It is generally believed to occur more frequently during the perioperative rather than the late postoperative period and in cases of acute rather than chronic AD (7,10,11). However, the exact mechanism responsible for the formation of these intimal tears has not been clearly elucidated to date. In our experience with TEVAR for complicated acute and chronic aneurysmal AD (in a total of 24 patients), we have encountered four cases of intimal disruption, which occurred in a delayed fashion in three patients, at the proximal and distal margins of the stent graft. In all cases, these lesions progressed to intimal flap/pseudo- aneurysm formation. We believe this phenomenon, defined in this report as an “intimal blowout,” needs to be recognized as an important clinical consequence of stent-graft therapy in a dissected aorta. MATERIALS AND METHODS The ethics review board at our institution approved the present case review. Patient characteristics and TEVAR details are described in the Table. All three patients & SIR, 2013 J Vasc Interv Radiol 2013; 24:1471–1475 http://dx.doi.org/10.1016/j.jvir.2013.05.066 From the SIR 2012 Annual Meeting. J.K.W., J.J.A., and E.H.J. are paid consultants for W.L. Gore and Associates (Flagstaff, Arizona). J.K.W. receives conference travel grants from Cook (Bloomington, Indiana). Neither of the other authors has identified a conflict of interest. From the Division of Interventional Radiology, Department of Diagnostic Imaging (A.M., E.J.H., J.K.W.), Foothills Medical Centre; and Division of Cardiac Surgery, Libin Cardiovascular Institute of Alberta (J.J.A., W.K.), University of Calgary, 1403 29th St. NW, Room G29, Calgary, Alberta, Canada T2N 2T9. Received January 28, 2013; final revision received May 27, 2013; accepted May 28, 2013. Address correspondence to A.M.; E-mail: ani. mirakhur@gmail.com