Abstract 16541: Clinical and Imaging Phenotypes From a Registry of Segmental Arterial Mediolysis

Abstract

Background: Segmental arterial mediolsyis (SAM) is a non-inflammatory arteriopathy that is increasingly being recognized; however, its clinical characteristics and natural history remain poorly defined. Methods: A retrospective, single-institution review of 20 patients presenting with arterial dissection, intramural hematoma, aneurysm, or occlusion between 2015 and 2020 was performed. To establish a non-invasive diagnosis of SAM, patients with FMD, inflammatory, or genetic arteriopathy were excluded by clinical, laboratory, and imaging criteria according to multidisciplinary guidelines. Patient demographics, clinical features, imaging findings, and management were assessed. Results: The average age of patients was 56 years; 75% were male. CAD was present in 15% of patients and 45% had hypertension; 55% were current or prior smokers. In patients without diagnosed CAD, the 10-year ASCVD risk score was 8.7% and the Framingham risk score was 6.8%. The average hemoglobin A1c was 5.6%. Acute onset abdominal pain (70%) was the most frequent presenting symptom. On average, two different arterial beds were affected at the time of diagnosis, most often in the abdomen. Arterial dissection was present in 75% of patients, and intramural hematoma was seen in 35% of cases. The most affected vessel was the superior mesenteric artery (50%), followed by the celiac, renal, and iliac arteries (35% each). Over a mean follow-up period of 20 months, all patients survived; two patients required intervention due to worsening clinical symptoms. Anticoagulation (AC) was utilized in 50% of cases, most commonly for one month. Long-term follow-up imaging was available in 11 patients; 3 patients (27%) had progression in lesion size over the first month. By 1 year, only 1 patient continued to show enlargement, with all others showing regression. Conclusions: This cohort provides longitudinal follow-up on both clinical and imaging characteristics of non-invasively diagnosed SAM. The condition shows a male predominance, typically manifesting in middle-aged patients with low to intermediate cardiovascular risk. While a subset of patients shows growth in size of the affected vascular segment over the first month, longer follow-up imaging demonstrates regression.