The role of aortomesenteric angle in occurrence of spontaneous isolated superior mesenteric artery dissection

Background: This study investigated whether anatomical factors affect the occurrence of SISMAD by measuring the aortomesenteric angle (AMA). Methods: The study population is comprised of 3 distinct population; Korean SISMAD patients, two control groups from a medical checkup database of 4997 Korean and 317 Caucasian patients from 2011 to 2016. The patient group (PG) included 26 symptomatic patients and 19 Korean diagnosed with SISMAD during medical checkup. The control group was selected based on propensity score similarities calculated by using the following covariates: Sex, age, body mass index, drinking, smoking, hypertension, diabetes, and cancer. We compared PG with equal numbers of two control groups comprised of Koreans (KG) and Caucasians (FG), respectively. Results: The mean (SD) AMA was 74.9o (17.5) (range, 45.9-110.9o) in the PG, 56.8o (19.5 (range, 10.2o -91.9o) in the FG, and 62.4o (19.1) (range, 25.4-110.8o) in the KG. A significant difference was observed between PG and the two control groups (P<0.001). The AMA in the FG was significantly more acute than the AMA in Korean patients including those in the PG and KG (P=0.001). Conclusions: Large AMA is considered to be an important etiologic factor in SISMAD.