RS27 - Natural History and Long Term Follow up of 890 Splenic Artery Aneurysms

Objectives: Though splenic artery aneurysms are the most common visceral aneurysm, there is a paucity of literature on the natural history of SAAs. The objective of this study was to review the natural history of patients with SAA.

Methods: This single-institution retrospective analysis studied all patients with SAA diagnosed by CT imaging between 2015 and 2019, identified by our radiology database. Imaging, demographic, and clinical data was obtained via the EMR.

Results: The cohort consists of 853 patients with 894 SAA. 693 were female (81.2%), with 37 (5.3%) of them of childbearing age (15-50 years). Mean age at diagnosis was 70.9 (28-100) years. Medical comorbidities included hypertension (70.2%), prior smoking (32.2%), and hypercholesterolemia (54.7%) (Table I). Imaging indications included abdominal pain (37.3%), unrelated follow-up (28.0%) and follow-up of a previously noted visceral artery aneurysm (8.6%).

Mean diameter at diagnosis was 13.3±6.3mm. 81 patients (9.0%) had more than one SAA. Anatomical locations included the splenic hilum (36.0%), distal splenic artery (30.3%), mid splenic artery (23.9%), and proximal splenic artery (9.7%). Radiographically, majority were saccular aneurysms (72.4%). Additional characteristics included calcification (88.5%) and thrombus (13.9%). Associated imaging findings included aortic atherosclerosis (58.7%), abdominal aortic aneurysms (7.0%), and additional visceral aneurysms (4.1%). One patient (38-year-old female) was initially diagnosed at the time of rupture of a 25mm aneurysm; this patient underwent immediate endovascular intervention with no complications.

Mean clinical follow-up among 812 patients was 4.1±4.0 years. Mean radiological follow-up among 514 patients was 3.8±6.8 years. Of these, 122 patients (23.7%) experienced growth, with mean growth of 2.5mm. Aneurysm growth rates for initial sizes < 10mm (n=123), 10-19mm (n=353), 20-29mm (n=34), and >30mm (n=4) were 0.166 mm/yr, 0.172 mm/yr, 0.383 mm/yr, and 0.246 mm/yr, respectively. Of the entire cohort, 27 patients (3.2%) eventually underwent intervention (81.5% endovascular), with the most common indications including size/growth criteria (70.4%) and symptom development (18.5%).

On multivariate analysis, only prior tobacco use (p=.028) was significantly associated with aneurysm growth. Data stratified by sex and childbearing age are presented in Table II.

Conclusions: The majority of SAAs in this cohort remained stable in size, with few patients requiring intervention over mean follow-up of 4 years. Current guidelines recommending treatment of asymptomatic aneurysms >30mm appear appropriate given their slow progression. Despite societal recommendations for intervention for all SAAs among women of childbearing age, only a minority underwent intervention in this series, indicating that these recommendations may not be well known in the general medical community.