Acute intramural hematoma of the aorta: A mystery in evolution

Abstract

Conclusion: There is a 5-7% prevalence of intramural hematoma (IMH) in patients with acute aortic syndromes with 16% of patients evolving to classic aortic dissection (AD) on subsequent imaging studies and a 40% mortality rate of ascending aorta IMH. Summary: Acute aortic syndromes are characterized by a sudden onset of thoracic pain and consist of both classic AD and intramural aortic hemorrhage. There is an incomplete knowledge of the natural history of IMH. The International Registry of Aortic Dissection (IRAD) involves eighteen referral centers in six countries. Potential patients for inclusion in IRAD are identified prospectively or retrospectively by searching hospital discharge records. Diagnosis of acute aortic syndrome is suspected on history and physical examination and confirmed by imaging study or surgical exploration or post mortem examination. The current study represents 1,1010 patients enrolled between January 1, 1996 and November 19, 2001. Fifty-eight (5.7%) of patients had IMH. Patients with IMH tended to be older (68.7 years) than those with classic AD (61.7 years, P < 0.001). Patients with IMH were also more likely to have distal aortic involvement than patients with classic AD (60.3% versus 35.3%; P < 0.001). Patients with IMH described more severe initial pain than those with classic AD. Patients with IMH, however, were less likely to have pulse deficits, ischemic leg pain, or aortic valvular insufficiency. Overall, mortality of IMH was similar to AD (20.7% versus 23.9%; P = 0.57). Mortality of patients with IMH of the descending aorta was 8.3% versus 13.1% of patients with AD of the descending aorta (P = 0.60). Mortality of patients with IMH of the ascending aorta was 39.1% versus 29.9% of patients with classic AD of the ascending aorta; P = 0.34. Sixteen percent of patients with an initial diagnosis of IMH progressed to AD on serial imaging studies. Comment: The natural history of acute IMH of the aorta as well as its prevalence is difficult to determine. The current study suggests that the prevalence of IMH in patients with non-traumatic acute aortic syndromes is about 6%. This is lower than previously reported. Overall, however, this study, and others suggest, that despite the more limited aortic involvement of IMH and the absence of true dissection flaps at initial presentation, the overall natural history of the disease is similar to that of classic AD. At this point the known natural history of IMH suggests treatment and follow up should be similar to AD.