ADSORB: a prospective randomised study on the efficacy of endovascular grafting vs. best medical treatment in uncomplicated acute dissection of the descending aorta.

Many of the arterial lesions that vascular surgeons treat are on the decline, and those that currently are may soon be offered more effective drug therapy. In contrast, dissections of the aorta are increasing and are likely to represent a significant future workload and challenge for vascular surgeons. Traditionally acute Stanford type B dissections of the aorta were managed by a variety of specialists, often cardiologists. Vascular surgeons only became involved where peripheral ischaemia supervened. Dake demonstrated the feasibility of placing endovascular stentgrafts in to dissected aortas. 1 This approach appeared to offer an attractive alternative to traditional open surgical approaches for complicated aortic dissection which carried high rates of complications. 2 Consequently stent-grafts have been used increasingly in this group of patients. 3 Early efforts to reduce mortality from acute type B dissection demonstrated that effective blood pressure control in the early stages reduced mortality. Medical therapy did not necessarily prevent long-term aortic related complications. The INSTEAD Trial attempted to answer the question whether there was any benefit from placing a stent-graft in type B aortic dissection in the subacute phase (2e52 weeks). 4 There was no reduction in aortic related mortality 2 years after the initial dissection but preliminary data from INSTEAD suggests that stent-grafting might be protective in the longer term (5 years). The next question is whether there would be any additional benefit (or harm) from stenting patients within the first 2 weeks of their initial uncomplicated type B dissection? There remains scope for improvement in the 10% in-hospital mortality when treated with medical therapy. 5 It is possible that stenting might reduce mortality. However, concerns remain (due in part to a lack of data) that stenting within the first 2 weeks may be associated with significant risks even when the aortic dissection is uncomplicated. It is for these reasons that we have been following the development of the ADSORB trial keenly since its inception in 2002. Recruitmenthasbeenslow,suggestingalackofclinicalequipoiseand the change of power calculation is regrettable but seems realistic if the triallists are to complete their study. It is a pity that the trial will not have the power to demonstrate significant differences in the more robustclinicalendpoints (aortic relatedorall-causemortality). It is not clear whether the primary trial composite endpoint of a variety of aortic related events (false lumen thrombosis, aortic dilatation >5 mm, aortic rupture) at 1-year will be a clinically relevant one for patients. In the INSTEAD Trial 20% of patients managed non-operativelyachievedfalselumenthrombosis.Itisquite possible that this group of patients receiving early stent-grafting in the ADSORBtrialmightnotderiveanybenefitatall(andmaybeharmed).