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

OBJECTIVES: Patients with Stanford type B dissection who have been treated successfully with medical hypotensive therapy during the acute phase (< 14 days) have the risk of surgery during the chronic phase because of enlargement of the dissected aorta. The objective of this retrospective analysis is to determine the predictors of surgical indications for acute type B aortic dissection by studying chronic-phase enlargements of aortic dissection in patients treated successfully with medical hypotensive therapy.

METHODS: Altogether, 131 patients with type B aortic dissection were treated medically during the acute phase between 1987 and 2004. Multivariate factor analyses were performed to determine the predictors of chronic-phase enlargement (> or = 55 mm, as defined for our surgical criteria) of the dissected aorta.

RESULTS: Overall dissection-related mortality was 17.6%. Patency of the false lumen was an independent risk factor for dissection-related death (P = 0.0238, hazard ratio 2.594, confidence interval 1.009-6.122) and for dissection-related events (P = 0.0157, hazard ratio 1.870, confidence interval 1.116-3.133). The incidence of patients treated surgically during the chronic phase was 32.8%. The predictors for aortic enlargement during the chronic phase were the condition of maximum aortic diameter > or = 45 mm with a patent false lumen during the acute phase. The rates of freedom from aortic enlargement (> or = 55 mm) for patients with maximum diameter (> or = 45 mm) with a patent false lumen during the acute phase at 1, 5, and 10 years were 72.6%, 66.0%, and 42.8%, respectively, whereas in patients with a maximum aortic diameter of < 45 mm with a thrombosed false lumen the values were 100%, 94.7%, and 89.2%, respectively (P < 0.005).

CONCLUSIONS: These data suggest that patients with acute type B dissection with a patent false lumen or a diameter > or = 45 mm (or both) during the acute phase are at risk for enlargement of the dissecting aorta. The patients with dissecting aortas > or = 45 mm or a patent false lumen (or both) therefore require close follow-up to detect enlargement of the dissecting aorta, whereas patients with a maximum aortic diameter of < 45 mm with a thrombosed false lumen can stay on conservative therapy.