Acute and Chronic Complications of Aortic Intramural Hematoma on Follow-up Computed Tomography: Incidence and Predictor Analysis

Objective: To ascertain the incidence of acute and chronic complications of aortic intramural hematoma (IMH) and to analyze the predictors of the development of each complication. Materials and Methods: This retrospective study includes 107 consecutive patients diagnosed with aortic IMH by means of computed tomography (CT) during the period from January 1998 to December 2003 and followed up with serial CT examinations (median follow-up period, 320 days). There were 36 patients with type A and 71 with type B IMH. Initial and follow-up CT scans were reviewed, with special attention given to the development of complications, such as increase in the thickness of IMH, clinical and hemodynamic evolution requiring urgent surgery, and development of aortic dissection and/or aneurysm. If each complication developed within 30 days after the initial episode, we classified it as an acute complication; the others were classified as chronic complications. The time interval between the initial and the subsequent CT examination showing each complication was recorded. To identify the predictors of each complication, we analyzed the demographic and CT findings with regard to the following factors: age, sex, maximum thickness of the hematoma, maximum aortic diameter on initial CT examination, ulcerlike projection (ULP) on initial and follow-up CT examinations, and the degree of atherosclerosis. The Cox proportional hazards regression model with stepwise multivariate analyses was used to determine the significant predictors of each complication. Results: Sixteen patients had acute complications consisting of aortic dissection (n = 7), aortic aneurysm (n = 6), and acute clinical and hemodynamic evolution requiring operation (n = 3). Three additional patients with aortic dissection (n = 1) and aneurysm (n = 2) underwent emergency surgery. Twenty-three patients with chronic complications had aortic dissection (n = 3), and aortic aneurysm (n = 20). Cox proportional hazards regression model revealed that the maximal diameter of involved aorta is the only significant predictor of the development of acute complications (P = 0.006), whereas the age (P = 0.040), type A IMH (P = 0.015), presence of ULP (P = 0.015), and newly developed ULP as revealed on follow-up CT examination (P = 0.032) were significant predictors of the development of chronic complications. With regard to the aortic dissection in 10 patients (9.3%; type A/B ratio, 5:5; median time interval, 34 days), Cox proportional hazards regression model revealed that the maximal thickness of the hematoma is the only significant predictor (P = 0.018). Twenty-one saccular and 5 fusiform aneurysms (24.3%) developed, as revealed on follow-up CT examinations (median time interval, 180 days). The presence of ULP (P = 0.030), type A (P = 0.038) and the maximal thickness of the hematoma (P = 0.017) were significant predictors for the development of an aneurysm. Conclusions: The maximum thickness of a hematoma on the initial CT is the significant factor predicting the development of aortic dissection and aortic aneurysm. Patients with type A IMH and ULP, as revealed by initial and short-term follow-up CT examinations, should be carefully followed up with subsequent CT examination to monitor the development of an aortic aneurysm, which is a relatively common chronic complication of IMH.