This clinical trial is a prospective, multicenter, open label study designed to evaluate the effectiveness and the safety of the Allay® Aortic Stent as adjunctive endovascular treatment of Type B aortic dissection in patients eligible for thoracic endovascular aortic repair with stent grafts.

Thoracic endovascular repair (TEVAR) with stent grafts is recommended for patients with acute complicated or high-risk type B aortic dissection (TBAD) as part of standard of care per current medical guidelines. Although the benefits of TEVAR with stent grafts are well established, there remains a significant risk of late complications, including aortic growth requiring reinterventions, or progression and/or rupture.

In the present clinical investigation, the investigational procedure of adjunctive thoracic stent graft extension with the Allay® Aortic Stent will consist of the placement of a CE-marked Thoracic Stent Graft in the descending thoracic aorta (proximal to the celiac trunk) followed by the implantation of the Allay® Aortic Stent as adjunctive treatment of TBAD.

The study objective is to demonstrate that the Allay® Aortic Stent, used as adjunctive endovascular treatment of Type B aortic dissection in patients eligible for thoracic endovascular aortic repair with stent grafts, results in a low rate of aortic growth requiring secondary reintervention, including open conversion, or aortic rupture in the treated abdominal segment at 12 months. The study will also allow to evaluate the incidence of Major Adverse Events (MAE) following TEVAR, at 30 days post-implantation of the Allay® Aortic Stent.

Based on available data on similar devices, the objective performance goal is set to an expected proportion of 85% freedom from aortic growth requiring secondary reintervention or aortic rupture of the abdominal segment at 12 months.

Inclusion Criteria:

• Have a type B aortic dissection extending to the celiac trunk or beyond
• Are eligible for thoracic endovascular treatment with stent grafts as per local guidelines, and physician's decision
• Have been elected for treatment with commercially available stent graft as per their IFU within 90 days of dissection symptoms onset

Exclusion Criteria:

• General Exclusion Criteria:

  • Age < 18 years
  • Pregnant, breast-feeding or planning on becoming pregnant during the entire duration of the study
  • Unable to provide written informed consent
  • Unable or unwilling to comply with the requirements of the study protocol
  • Taking part already in an investigational device or drug study that could interfere with the outcomes being studied
  • Active drug addiction or known history of drug abuse within one year of treatment

• Medical Exclusion Criteria:

  • Aortic rupture, free or contained including haemothorax, increasing periaortic hematoma, or mediastinal hematoma
  • Aortic fistula
  • Suspicion of bowel necrosis or irreversible visceral ischemia
  • Stage 5 chronic kidney disease
  • Life expectancy of less than 2 years due to any other medical condition than the dissection to be treated
  • Active malignancy
  • Known sensitivities or allergies to the device materials (including cobalt, chromium, nickel)
  • Known sensitivities or allergies to contrast materials that cannot be pre-medicated
  • Mycotic aortic aneurysm or active systemic infection that may place the patient at increased risk of endovascular infection
  • American Society of Anaesthesiologists (ASA) class V (moribund patient not expected to live 24 hours with or without operation)
  • Diagnosed or suspected congenital degenerative connective tissue disease (e.g., Marfan's, Loeys-Dietz or Ehlers-Danlos syndrome)
  • Uncorrectable coagulopathy, bleeding diathesis or refusal of blood transfusion
  • Any major cardiovascular or cerebrovascular ischemic event, including myocardial infarction or stroke, or treatment of such event, within 90 days prior to enrolment
  • Any aortic-related interventional or surgical procedure within 30 days prior to enrolment
  • Any planned aortic-related interventional or surgical procedure within 30 days after the study procedure

• Anatomical Exclusion Criteria:

  • Aneurysmal dilatation of the false lumen defined as maximum transaortic diameter >55 mm in women or >60 mm in men in the thoraco-abdominal segment or >50 mm in women or >55 mm in men in the abdominal segment, measured inner-wall to inner-wall;
  • Inadequate proximal landing zone for the stent graft, such zone being <20 mm long
  • Inadequate proximal landing zone geometry for the Allay® Aortic Stent (e.g. aortic kink)
  • Planned implantation of a stent graft with a distal diameter >38 mm or <20 mm
  • Aorta or iliac anatomy not allowing the advancement of the delivery system
  • Subject in whom the thoracic stent graft is either 1) not implanted in its intended position and/or 2) leads to any serious device complication, and/or who has 3) persistent static obstruction of the visceral or both renal arteries, prior to Allay® Aortic Stent implantation, will not be implanted with the Allay® Aortic Stent and will be withdrawn from the study