Partial thrombosis of the false lumen in patients with acute type B aortic dissection.

BACKGROUND: Patency or thrombosis of the false lumen in type B acute aortic dissection has been found to predict outcomes. The prognostic implications of partial thrombosis of the false lumen have not yet been elucidated. METHODS: We examined 201 patients with type B acute aortic dissection who were enrolled in the International Registry of Acute Aortic Dissection between 1996 and 2003 and who survived to hospital discharge. Kaplan-Meier mortality curves were stratified according to the status of the false lumen (patent, partial thrombosis, or complete thrombosis) as determined during the index hospitalization. Cox proportional-hazards analysis was performed to identify independent predictors of death. RESULTS: During the index hospitalization, 114 patients (56.7%) had a patent false lumen, 68 patients (33.8%) had partial thrombosis of the false lumen, and 19 (9.5%) had complete thrombosis of the false lumen. The mean (+/-SD) 3-year mortality rate for patients with a patent false lumen was 13.7+/-7.1%, for those with partial thrombosis was 31.6+/-12.4%, and for those with complete thrombosis was 22.6+/-22.6% (median follow-up, 2.8 years; P=0.003 by the log-rank test). Independent predictors of postdischarge mortality were partial thrombosis of the false lumen (relative risk, 2.69; 95% confidence interval [CI], 1.45 to 4.98; P=0.002), a history of aortic aneurysm (relative risk, 2.05; 95% CI, 1.07 to 3.93; P=0.03), and a history of atherosclerosis (relative risk, 1.87; 95% CI, 1.01 to 3.47; P=0.05). CONCLUSIONS: Mortality is high after discharge from the hospital among patients with type B acute aortic dissection. Partial thrombosis of the false lumen, as compared with complete patency, is a significant independent predictor of postdischarge mortality in these patients.