Abstract 334: Narrative Review of the Incidence, Course and Treatment of In Stent Stenosis after Flow Diverter Placement

IntroductionFlow diversion has evolved as a standard treatment for aneurysms with giant, wide necked or fusiform morphology. Flow Diverters promote aneurysm treatment by intrasaccular stasis and thrombus formation within the aneurysm and endothelialization of the stent leading to reconstruction of the parent artery1. In stent stenosis (ISS) of the parent artery is one complication with flow diverters. We aim to describe the incidence, definition, radiographic and clinical courses and treatment paradigms as described in the literature.MethodsA literature search was conducted using Nested Knowledge with keywords related to “flow diverter,” and “in stent stenosis”. Studies were then reviewed by two independent reviewers who screened the selected articles. Articles were excluded if they included less than 5 patients, did not report stenosis rates, contained non‐clinical data or used MRA/CTA for follow up. If duplicate data from the same center was identified the larger study was used. A standardized data collection form was utilized. Data on rates of incidence and definition of ISS on follow up, progression, clinical complications and treatments of ISS were collected.ResultsThe incidence of ISS on follow up varied significantly (Figure 1) with most studies reporting an incidence of between 0 to 20 percent on angiographic follow up. ISS was measured as the lumen inside the stent construct over healthy adjacent lumen, stent borders, lumen prior to stent placement or other in 5/47, 9/47, 3/27 and 2/47 studies respectively. 28/47 studies did not define how ISS was measured. Time of angiographic follow up varied from 2‐36 months with a median of 6 months. 18 out of 47 studies reported on radiographic course on subsequent follow up with all studies showing a majority of patients showing stability or improvement of ISS. Clinical complications from ISS developed in a minority of patients. Intervention was pursued in a minority of patients and balloon angioplasty was the most common treatment.ConclusionIncidence of ISS varied greatly due to a lack of uniform measurement definition, wide range of angiographic follow up and types of devices used. Only a minority of patients developed clinical complications from ISS and a majority of patients showed radiographic improvement or stability. A uniform definition of ISS such as NASCET criteria in carotid stenosis may be helpful in order to better evaluate the phenomenon of ISS.1. Dandapat S, Mendez‐Ruiz A, Martìnez‐Galdámez