Background: An aortic intramural hematoma (IMH) is a form of aortic dissection (AD). IMHs regress with time or completely disappear in some patients, whereas they progress to overt AD in other patients. The purpose of the present study was to investigate how IMHs change serially during a follow-up period.
Methods and results: We analyzed 44 consecutive medically treated patients with IMHs, in whom transesophageal echocardiography (TEE) was performed serially at both 1 and 6 months after the onset. After TEE, the patients were followed with interviews (mean follow-up 1552+/-539 days). IMHs disappeared at 6 months in 21 patients (48%) (disappearance group), whereas IMHs were still demonstrated at 6 months in 20 patients (45%) (persistent group); in the disappearance group, IMHs disappeared at 1 month in 8 patients (18%). In 3 patients (7%) in whom an IMH was demonstrated at 1 month, overt AD occurred until 6 months. The disappearance group was younger than the persistent group (64+/-11 versus 72+/-8 years, P:<0.01), and the maximum diameter of the aorta was smaller in the disappearance group than in the persistent group (33+/-5 versus 42+/-7 mm, P:<0.01). During the long-term follow-up, overt AD occurred at 7 and 11 months in 2 patients, and progressive aortic dilatation that required surgical treatment occurred at 12 and 24 months in 2 of the persistent group patients, whereas neither overt AD nor progressive aortic dilatation occurred in the disappearance group. In the patients in whom overt AD occurred, the maximal aortic diameter was >45 mm and an IMH was demonstrated at 1 month. On the other hand, those with a maximal aortic diameter of <45 mm or a disappeared IMH did not have overt AD.
Conclusions: IMHs disappeared until 1 month in 18% and until 6 months in 48% of patients with IMHs. The disappearance of IMHs was related to the maximum diameter of the aorta and age. Both a disappeared IMH and a maximal aortic diameter of <45 mm suggest a good prognosis.