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

OBJECTIVES 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.