Determining surgical indications for acute type B dissection based on enlargement of aortic diameter during the chronic phase.

BACKGROUND: In patients with Stanford type B dissection who have been treated successfully with medical hypotensive therapy during the acute phase, a large number have incurred the risk of surgery during their chronic phases because of enlargement of the dissected aorta. The purpose of this study was to determine the indications for surgical treatment of acute type B dissection by studying chronic-phase enlargements of aortic dissections in patients treated successfully with medical hypotensive therapy during the acute phase.

METHODS AND RESULTS: In 41 patients with type B dissection who had been treated medically during the acute phase, univariate and multivariate factor analyses were made to determine the predominant predictors for chronic-phase enlargement (> or = 60 mm) of the dissected aorta. Computed tomography was performed every 4 to 14 months to observe whether there was enlargement of the maximum aortic diameter. The predominant predictors for aortic enlargement in the chronic phase were the existence of a maximum aortic diameter of > or = 40 mm during the acute phase (P < .001) and a patent primary entry site in the thoracic aorta (P = .001). The values of actuarial freedom from aortic enlargement for the patients with a large aortic diameter (> or = 40 mm) during the acute phase and a patent primary entry site in the thorax at 1, 3, and 5 years were 70%, 29%, and 22%, respectively. No aortic enlargement was observed in the other patients throughout the entire follow-up period.

CONCLUSIONS: These data suggest that patients with acute type B dissection who have a large aortic diameter (> or = 40 mm) and a patent primary entry site in the thorax should be treated surgically during the acute phase on the condition that the surgical risk in this phase is limited.