Acute abdominal aortic dissection: insight from the International Registry of Acute Aortic Dissection (IRAD).

Background: Isolated acute dissection of the abdominal aorta is an unusual event that may present with several different clinical scenarios. Because its incidence is low, the natural history is unknown. We report data from the International Registry of Acute Aortic Dissection (IRAD), the largest group of patients treated for acute aortic dissections. The aim of this study was to identify clinical characteristics, therapeutic approaches, risk factors for mortality, in-hospital outcome, and long-term results of this cohort, thus clarifying its natural history.

Methods: A comprehensive analysis of 290 clinical variables on 18 patients affected by isolated acute abdominal aortic dissection (IAAAD) was performed. Among 1417 patients enrolled in the IRAD from 1996 to 2003, 532 (37.5%) had an acute type B dissection, of which 18 (1.3%) had an IAAAD. Theor mean age was 67.7 +/- 13.3 years, with a male predominance (n = 12, 67%). Aortic aneurysms pre-existed in 5 patients (28%). IAAAD was iatrogenic in 2 cases (11%).

Results: Compared with patients with type B aortic dissections, abdominal pain, mesenteric ischemia or infarction, limb ischemia, and hypotension as initial clinical signs were significantly more frequent in patients with IAAAD, whereas chest pain was more typical in patients with type B dissections. No neurologic symptoms, such as ischemic spinal cord damage or ischemic peripheral neuropathy, occurred in the IAAAD cohort. The 18 IAAAD patients were medically, surgically, or percutaneously managed in 12 (66.6%), five (27.8%), and one (5.6%) cases, respectively. The overall in-hospital mortality rate was 5.6% (n = 1). The patient who died was medically managed. No deaths were reported among patients who underwent surgery or had an endovascular procedure, irrespective of their preoperative status. A mean follow-up of 5 years (range, 1 month to 9 years) was completed for 71% (12 of 17) of the patients. Four patients (33.3%) died during the 9-year follow-up period. Overall survival was 93.3% +/- 12.6% at 1 year and 73.3% +/- 27.2% at 5 years. All patients who died during the follow-up period had in-hospital medical management (P = .04).

Conclusions: IAAAD is a condition that may present differently compared with classic type B aortic dissections. IAAAD patients treated with surgical or endovascular procedures had a lower unadjusted in-hospital and long-term mortality rate compared with medically managed patients. On the basis of the present natural history report, continued surveillance appears mandatory. To improve the life expectancy of patients with IAAAD, aggressive surgical or endovascular management seems justified.