A systematic review and meta-analysis of isolated abdominal aortic dissection

Objective: Isolated abdominal aortic dissection (IAAD) has remained poorly understood because of its rarity. We explored the prevalence, clinical characteristics, risk factors, imaging characteristics, and treatment strategy of IAAD to facilitate its diagnosis and treatment. Methods: We performed a meta-analysis of 17 studies, with single-arm-based and network meta-analysis as the main data synthesis method. The Medline, Embase, and Cochrane library were searched from their inception to July 2018. A total of 9163 patients with aortic disease were enrolled, with IAAD identified in 491 patients. Results: The pooled prevalence of IAAD among cases of aortic dissection overall, type B aortic dissection, and type A aortic dissection was 1.7% (95% confidence interval [CI], 0.9%-3.4%), 4.1% (95% CI, 2.5%-6.6%), and 2.0% (95% CI, 0.7%-3.9%), respectively. Abdominal pain was the most common symptom (50.8%), followed by back pain (30.5%), and chest pain (21.7%). Up to 41.0% of the patients with IAAD did not present with any clinical symptoms, and up to 71.0% of these patients had negative findings on physical examination. The top three most prevalent risk factors for IAAD were hypertension, hyperlipidemia, and smoking. Most cases of IAAD were limited to the aorta inferior to the renal arteries (81.7%), and the average aortic diameter was 4 cm. No statistically significant difference was observed between open surgery, endovascular aortic repair, and conservative management for both early and late mortality. Conclusions: The results from the present meta-analysis regarding IAAD support the following conclusions and recommendations. First, IAAD is rare and predominantly affects males. Second, symptoms (pain) might or might not be present, and physical findings will rarely be found on abdominal examination. Third, hypertension is the most prevalent risk factor. Fourth, most cases IAAD will be infrarenal. Finally, a complication-specific approach, similar to that for type B aortic dissection, would be appropriate.