The differences and similarities between intramural hematoma of the descending aorta and acute type B dissection

This retrospective analysis compares outcomes in patients with aortic intramural hematoma type B (IMHB) to those with type B aortic dissection (ABAD) in patients enrolled in the International Registry of Acute Aortic Dissection (IRAD).  There was no difference in in-hospital mortality between the two groups.  Patients with IMHB required surgical intervention less frequently than ABAD, with the indications for intervention being the same for the two groups (rupture, malperfusion, refractory pain or hypertension).  Periaortic hematoma was observed more often in patients with IMHB and was identified as a risk factor for rupture.  Patients with ABAD had significantly more dilation of the descending aorta during follow up and more often had extension into the abdominal aorta than those with IMHB.  The authors concluded that IMHB may have a more indolent clinical course than ABAD.