LAUSR

Objective: This study aimed to determine the natural history of spontaneous isolated abdominal aortic dissection (SIAAD) and to establish an optimal management strategy for patients with SIAAD. Methods: We searched the database of thoracoabdominal computed tomography (CT) performed at a single institution from January 2003 to July 2016 using the keywords “aortic dissection” and “dissection AND aorta.” Once a diagnosis of SIAAD was made, we investigated the initial clinical and morphologic features and aorta‐related events for all patients and morphologic changes of the aortic dissection (AD) during the follow‐up period for the patients who underwent follow‐up CT scans. We compared characteristics of the patients, frequencies of clinical events (aortic rupture, intervention, death), and morphologic changes (false lumen enlargement, progression of AD, remodeling of AD, and involvement of iliac or visceral artery) during the follow‐up period according to the location of AD (infrarenal vs suprarenal), symptom status (symptomatic vs asymptomatic), and gender. Results: There were 210 (10.7%) patients (median age, 69.4 years [interquartile range, 61.3–74.7]; male, 73.3%) who were diagnosed with SIAAD among 1958 patients with AD. SIAAD was most frequently located at the infrarenal aorta (86.2%), extended to the iliac (12.4%) or visceral artery (2.9%), and was symptomatic in 13.3% of patients. During the study period, aortic rupture developed in two patients (0.9%), aortic intervention was required in five (2.4%), and aorta‐related deaths were identified in three (1.4%). Among 138 (65.7%) patients who underwent follow‐up CT scans, 81.9% showed no morphologic change or remodeling during the follow‐up period (median, 25 months; range, 1–158 months; interquartile range, 12.3–49.1 months). In the meantime, false lumen enlargement and longitudinal progression of AD developed in 8.7% and 6.5% of patients, respectively. However, newly developed visceral artery extension was not found in any of the patents. When characteristics of the patients and frequencies of clinical events or late morphologic changes of AD were compared on the basis of the location of AD, symptom status, and gender, female gender, presence of symptoms, and suprarenal SIAAD were more frequently associated with aorta‐related mortality. False lumen enlargement was more frequent in the suprarenal AD group than in the infrarenal AD group. Conclusions: Based on our observation, the majority of symptomatic and asymptomatic SIAAD patients can be managed conservatively unless they present with aortic rupture, concomitant large aortic aneurysm, or underlying connective tissue disease. However, a more proactive management strategy may be required for female, symptomatic patients or those with suprarenal SIAAD.