Tran and Khoynezhad If the diagnosis of a complicated type B AAD is conﬁrmed, patients should be immediately brought to a hybrid operating room for endovascular and/or surgical treatment options. Endovascular or surgical options may be offered to hemodynamically stable patients with a complicated type B AAD. Table 3 lists the indications for endovascular or surgical intervention in patients with type B AAD. Outcome The short term prognosis for patients with type B AAD is better than those with type A and the medical management of type B AAD is associated with less mortality compared to the open surgical intervention approach. Overall, 89% of patients with type B AAD survive to hospital discharge, although the in-hospital survival rates were as low as 29% for the highest risk group, 64% for the intermediate, and 97% for the lowest risk group.6,36 Aortic rupture, shock, and malperfusion are the most important in-hospital risks leading to poor outcome in up to 20% of these patients.6,35 Of survivors, 80% will develop aneurysmal dilatation of the false lumen, requiring cardio- thoracic surgical intervention in one third of the cases.35,37,38 Therefore, although medical management of patients with type B AAD is the standard of care at the moment, it is far from being an option with acceptable results to patients with uncomplicated type B AAD. The long term prognosis for patients with type B AAD is poor. Data from IRAD indicated about 1 out of 4 patients with type B dissection died at the 3-year mark regardless of the mode of therapy. The 3-year rates of survival were 77.6%, 82.8%, and 76.2% for patients treated medically, surgically, and with endovascular therapy, respectively.36 Umana and colleauges reported the outcome of 189 patients with type B aortic dissection over a 36-year period. Actuarial survival for all patients was 71%, 60%, 35% and 17% at one, ﬁve, 10, and 15 years regardless of medical or surgical therapy.33 A diameter 4 cm, patent false lumen, and a partially throm- bosed false lumen are independent predictors of poor long term outcome for type B dissection.39,40 Table 3 Indications for endovascular or surgical intervention in patients with type B AAD • Persistent or recurrent pain despite adequate antiimpulsive and anti- hypertensive therapy (at least two parenteral agents at moderate to high dose) • Acute expansion of the false lumen • Periaortic or mediastinal hematoma (contained rupture) • Visceral, renal or limb malperfusion syndrome Neurological deﬁcits (relative indication). 62 Future development Given the disappointing results of medical and surgical therapy in uncomplicated type B AAD, there has been inter- est in use of endovascular stenting along with antiimpulsive and antihypertensive treatment. The endovascular therapy is based on the concept that obliteration and thrombosis of the false lumen may result in improved long-term outcome. The INSTEAD trial was designed to address this question, but was associated with methodological ﬂaws by including patients with chronic type B aortic dissection.41 Ongoing and future trials will shed light on this issue. For complicated type B AAD, endovascular therapies are becoming the standard of care in the Centers of Excellence, because they have shown to have a better outcome compared to the open repair approach.29,42,43 Disclosure The authors report no conﬂicts of interest in this work. References 1. Osler W, Silverman ME, Murray TJ, et al. American College of Physicians. The quotable Osler. Philadelphia: American College of Physicians, 2003. 2. Coady MA, Rizzo JA, Goldstein LJ, et al. Natural history, pathogenesis, and etiology of thoracic aortic aneurysms and dissections. Cardiol Clin. 1999;17:615–35. 3. 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