RS22 - Spontaneous Isolated SMA Dissection: Natural History in A Large Contemporary Cohort

Objectives: Spontaneous isolated superior mesenteric artery dissection (SISMAD) is uncommon, and evidence guiding surveillance and intervention thresholds remains heterogeneous. We evaluated presentation, management, and longitudinal imaging outcomes in a large single-institution cohort of primary SMA dissection.

Methods: We retrospectively identified 237 patients diagnosed with primary SMA dissection between 2001–2024, defined as a dissection originating in the SMA without extension from an aortic dissection. Demographics, comorbidities, presenting symptoms, management strategy (conservative, endovascular, open), and longitudinal imaging outcomes were analyzed. Imaging outcomes were categorized as: stable (unchanged morphology or partial morphologic improvement on follow-up imaging), remodeling (complete radiographic resolution), and occlusion (complete SMA occlusion).

Results: The cohort was predominantly male (74.3%) with a mean age of 67.3 ± 13.2 years (Table I). Abdominal pain was the most common presenting symptom (57%), while 36.3% of cases were incidentally identified (Table II). Computed tomography angiography (CTA) was the primary diagnostic modality used in nearly all patients (97.5%) (Table III). Nearly half of the cohort had isolated primary SMA dissection (48.9%). Among the remaining patients, 22.4% had an aneurysm in another vascular territory, 14.8% had a dissection in a different vessel, and 13.9% had both aneurysmal and dissecting lesions in other vessels suggesting frequent multi-territory arteriopathy (Table I). Initial management was conservative in 90.7%, with endovascular repair in 3.0% and open repair in 6.3%, the primary indication for intervention was acute or acute on chronic mesenteric ischemia. On follow-up imaging, 70.5% demonstrated stable dissection, 23.2% achieved complete remodeling, and 3.4% progressed to SMA occlusion (Table IV).

Conclusions: In this large cohort, primary (spontaneous isolated) SMA dissection most often followed a favorable course with conservative medical management, with high rates of stability/remodeling and a low incidence of occlusion. These data support conservative therapy with structured imaging surveillance as first-line management, reserving intervention for defined clinical or morphologic triggers.