Stent grafts in type B aortic dissection – negative results

Stent grafts in type B aortic dissection – negative results

Stent grafts in type B aortic dissection – negative results: The INvestigation of STEnt Grafts in Aortic Dissection (INSTEAD) Trial [1], a randomized comparison of strategies for Type B aortic dissection found that thoracic endovascular aortic repair (TEVAR) failed to improve 2-year survival and adverse event rates in spite of favorable aortic remodeling.

An accompanying editorial in Circulation [2], while commenting that this trial has provided level 1 evidence, raised a concern that the negative result could be because the study was underpowered to evaluate the mortality endpoint. The study needed 28 events to have an adequate power while only 11 events were observed. The study randomized 140 persons with type B aortic dissection which was stable for at least 2 weeks into stent grafting vs optimal medical treatment strategies. The primary endpoint was all cause mortality at 2 years while secondary endpoints were aorta related death, progression (needing conversion or additional endovascular or open surgery) and aortic remodeling. In the TEVAR group there was 1 paraplegia, 1 stroke and 1 transient paraparesis while there was one paraparesis in the medical treatment group. Aortic remodeling with recovery of true lumen and thrombosis of thoracic false lumen occurred in 91.3% of TEVAR vs 19.4% in medical treatment group (P<0.001). There was no difference in the aorta related death rate nor was there any difference in the risk of the combined end point of aorta related death (due to rupture) and progression, including the need for further procedures.

Though the initial report was negative, the 2-5 year result was heartening [3]. TEVAR was associated with improved 5 year aorta-specific survival and delayed disease progression. Stent graft induced false lumen thrombosis was noted in 90.6% of cases.

References

  1. Christoph A Nienaber, Hervé Rousseau, Holger Eggebrecht, Stephan Kische, Rossella Fattori, Tim C Rehders, Günther Kundt, Dierk Scheinert, Martin Czerny, Tilo Kleinfeldt, Burkhart Zipfel, Louis Labrousse, Hüseyin Ince, INSTEAD Trial. Randomized comparison of strategies for type B aortic dissection: the INvestigation of STEnt Grafts in Aortic Dissection (INSTEAD) trial. Circulation. 2009 Dec 22;120(25):2519-28.
  2. Christopher J Kwolek, Michael T Watkins. The INvestigation of STEnt Grafts in Aortic Dissection (INSTEAD) trial: the need for ongoing analysis. Circulation. 2009 Dec 22;120(25):2513-4.
  3. Nienaber CA, Kische S, Rousseau H, Eggebrecht H, Rehders TC, Kundt G, Glass A, Scheinert D, Czerny M, Kleinfeldt T, Zipfel B, Labrousse L, Fattori R, Ince H; INSTEAD-XL trial. Endovascular repair of type B aortic dissection: long-term results of the randomized investigation of stent grafts in aortic dissection trial. Circ Cardiovasc Interv. 2013 Aug;6(4):407-16.