Descending aortic aneurysmal changes following surgery for acute DeBakey type I aortic dissection.

OBJECTIVE: The aim of the study was to determine the risk factors for descending aortic aneurysmal changes following surgery for acute DeBakey type I aortic dissection.
METHODS: A total of 129 patients who underwent surgery for acute type I aortic dissection between 2000 and 2010 were evaluated by contrast-enhanced computed tomography (CT) at least 6 months later (median follow-up 29.5 months, interquartile range 16.3-49.3 months). The study endpoint was the development of aortic aneurysms (diameter >55 mm). Risk factors for aortic aneurysms were determined by Cox regression analysis.
RESULTS: Aortic dilatation occurred in 23 of the 129 (17.8%) patients. Aortic aneurysms were observed at the proximal descending in 19 (14.7%) patients, the mid descending in 12 (9.3%) patients, the distal descending in seven (5.4%) patients and at the abdominal aorta in one (0.8%) patient. Multivariate analysis showed that the luminal diameter of the proximal descending aorta on initial CT was the only significant and independent factor predicting aneurysm formation (hazard ratio 1.12, 95% confidence interval [CI] 1.02-1.22, P = 0.014). Receiver operating curves assessing the ability of preoperative proximal descending aorta diameter to predict aortic aneurysms showed an area under the curve of 0.72 (95% CI 0.60-0.84, P = 0.001), with a greatest accuracy at 40.95 mm (sensitivity 65.2%, specificity 78.3%). The 5-year freedom from aortic aneurysm rates in patients with proximal descending diameters ≤ 40 and >40 mm were 84.4 ± 6.6 and 55.6 ± 11.1%, respectively (P = 0.001).
CONCLUSIONS: The proximal descending aorta was the major site of aneurysm formation following surgery for acute type I aortic dissection. The large proximal descending aortic diameter on initial CT predicted the late aneurysm, suggesting that adjunctive procedures combined with aortic replacement are needed to prevent the late aneurysm.