Background-Aortic intramural hematoma (IMH) is a variant of overt aortic dissection. The predictors of progression of IMH to dissection and rupture are still unknown, and strategies for management are not established. Methods and Results-A multicenter study was conducted comprising 66 patients with IMH and hospital admission Յ48 hours after onset of initial symptoms. Among these, progression to aortic dissection or rupture occurred in 30 (45%) and death occurred in 13 (20%) patients within 30 days. Late progression was noted in 14 (21%) and death in 11 (17%) patients, yielding a 1-, 2-, and 5-year survival of 76%, 73%, and 43%, respectively. In a set of 9 variables, multivariate analysis identified IMH location in the ascending aorta (type A; Pϭ0.02) and moderately ectatic aortic diameters (49Ϯ13 mm with progression versus 57Ϯ16 mm without progression; Pϭ0.03) as independent predictors of early progression. In type A IMH, early mortality was 8% with swift surgery versus 55% without surgery (Pϭ0.004). The risk of late progression of IMH was independently associated with age at index diagnosis (Pϭ0.01) and absence of ␤-blocker therapy during follow-up (Pϭ0.03). Kaplan-Meier analysis confirmed improved 1-year survival of IMH with ␤-blocker therapy (95% versus 67% without ␤-blockers; Pϭ0.004). Conclusions-Regardless of aortic diameter, IMH of the ascending aorta (type A) is at high risk for early progression, and, thus, undelayed surgical repair should be performed. Moreover, oral ␤-blocker therapy may improve long-term prognosis of IMH independent of anatomical location.

Background-Aortic intramural hematoma (IMH) is a variant of overt aortic dissection. The predictors of progression of IMH to dissection and rupture are still unknown, and strategies for management are not established. Methods and Results-A multicenter study was conducted comprising 66 patients with IMH and hospital admission Յ48 hours after onset of initial symptoms. Among these, progression to aortic dissection or rupture occurred in 30 (45%) and death occurred in 13 (20%) patients within 30 days. Late progression was noted in 14 (21%) and death in 11 (17%) patients, yielding a 1-, 2-, and 5-year survival of 76%, 73%, and 43%, respectively. In a set of 9 variables, multivariate analysis identified IMH location in the ascending aorta (type A; Pϭ0.02) and moderately ectatic aortic diameters (49Ϯ13 mm with progression versus 57Ϯ16 mm without progression; Pϭ0.03) as independent predictors of early progression. In type A IMH, early mortality was 8% with swift surgery versus 55% without surgery (Pϭ0.004). The risk of late progression of IMH was independently associated with age at index diagnosis (Pϭ0.01) and absence of ␤-blocker therapy during follow-up (Pϭ0.03). Kaplan-Meier analysis confirmed improved 1-year survival of IMH with ␤-blocker therapy (95% versus 67% without ␤-blockers; Pϭ0.004). Conclusions-Regardless of aortic diameter, IMH of the ascending aorta (type A) is at high risk for early progression, and, thus, undelayed surgical repair should be performed. Moreover, oral ␤-blocker therapy may improve long-term prognosis of IMH independent of anatomical location.

According to our experience, magnetic resonance imaging is the most accurate method for the diagnosis of an IMH.