Natural history of spontaneous isolated superior mesenteric artery dissection derived from follow-up after conservative treatment

Objectives Optimal treatment of spontaneous isolated superior mesenteric artery dissection (SISMAD) has not been established in part because the natural history of this rare vascular disease is not well established. We attempted to determine the natural history of SISMAD by observing patients who underwent conservative treatment. Methods Among 58 consecutive patients with SISMAD, 46 who underwent conservative treatment and periodic follow-up of computed tomography (CT) angiography (CTA) were included for this study. Our first-line treatment for SISMAD patients was conservative (n = 53), reserving interventional treatment, either endovascular (n = 1) or surgical (n = 4), for patients with persistent abdominal pain despite conservative treatment or signs of bowel ischemia. We retrospectively investigated changes of the length, type, or remodeling of the dissection and superior mesenteric artery patency on multidetector CT scan. To evaluate clinical course, presence of persistent or recurrent abdominal symptoms was queried on an outpatient base. Results After 23.0 (median, range 6.5-74.2) months, follow-up CT angiograms showed diminished extent of the false lumen size in 19 (41.3%), no change in 20 (43.5%), diminished length of dissection in 11 (23.9%), and complete remodeling of dissection in seven (15.2%) patients. No patient showed dissection progression on follow-up angiogram. During the follow-up period, 10 (26.3%) patients reported nonspecific, mild abdominal discomfort, however, no patient developed recurrent abdominal pain following conservative treatment. There was no mortality related with SISMAD. Conclusions After conservative treatment of SISMAD, we have observed that the majority of patients showed improvement or no change on both angiogram and clinical examination. We believe this observation supports an approach of conservative treatment for patients with SISMAD.