Acute non-A-non-B aortic dissection: surgical or conservative approach?

Objective: The indications for surgical approach in both type A and type B acute aortic dissections are widely recognized and accepted, but little is known about non-A-non-B dissection in which the aortic arch dissection is not accompanied by the involvement of the ascending aorta.

Methods: Between July 2002 and August 2014, all patients referred to our clinic with acute aortic dissection (n=281) were classified prospectively, taking into consideration the extent of dissection and the location of the intimal tear in three main segments of the aorta: the ascending aorta including the root, the transverse arch and the descending aorta. Accordingly, a total of 8 patients with a non-A-non-B dissection (isolated arch dissection, 1, or descending aorta and arch dissection, 7) were identified in addition to 187 type A and 86 type B dissections. Four patients (median age 62, range 61-81 years) with an entry in the arch underwent surgery, and 4 (median age 67, range 54-74 years) with an entry in the descending aorta were treated conservatively.

Results: All operated patients survived the surgery and remained alive without relevant clinical events during the median follow-up time of 40 months (range, 30-141). In contrast, 3 patients treated conservatively died 1, 3 and 28 months after onset of dissection, respectively. The cause of death was aortic rupture in 1 and progression of dissection with subsequent malperfusion in 2. Due to progressive enlargement of the chronic dissected aorta, a fourth patient underwent a complete replacement of the entire thoracic aorta via a clamshell approach 7 years after onset of acute dissection and was still alive at the last follow-up (30 months after surgery).

Conclusions: Compared with conservative therapy, surgery of an acute aortic dissection involving the arch but sparing the ascending aorta (non-A-non-B dissection) seems to offer improved clinical outcomes, especially from the long-term point of view, and it can be considered as a preferred therapeutic option. For further evidence, more observations are necessary, using clearly and unambiguously defined classifications that consider the extent of dissection and the site of intimal tear.