Clinical characteristics and outcomes in patients with acute type A aortic intramural hematoma.

Background: Although type A acute aortic dissection (AAD) including classic double-channel aorta and intramural hematoma (IMH) is a life-threatening condition, the prognostic impact and predictors of IMH remain to be established. The present study evaluated the prevalence, baseline characteristics, and outcomes of IMH as compared with classic non-thrombosed type A AAD.

Methods: This multicenter registry in Japan retrospectively included 703 patients with type A AAD. IMH was defined as a crescentic or circular area along the ascending aortic wall without contrast enhancement on computed tomography (CT). Non-thrombosed type A AAD was defined as the classic double-channel ascending aorta on contrast-enhanced CT. The primary endpoint was in-hospital mortality.

Results: Of the 703 patients with type A AAD, 312 (44.3%) had IMH. Older age was an only baseline patient factor significantly associated with the presence of IMH in the multivariable analysis. The longitudinal extent of dissection was greater in patients with classic non-thrombosed AAD than those with IMH, resulting in an increased risk of end-organ malperfusion in the classic AAD group. During the hospitalization, 41 (13.1%) and 85 (21.7%) patients with and without IMH died (p < 0.001). IMH was associated with lower in-hospital mortality in a multivariable model, irrespective of age and the implementation of surgery.

Conclusions: The present study showed that IMH on CT was frequent among patients with type A AAD. Although IMH was more likely to be present in the elderly, its effect on the better survival was independent of age and surgical treatment.