INSTEAD and IRAD – What have we learned?
The preliminary conclusion of the INSTEAD study, presented by Dr Christoph Nienaber, Germany, is that for uncomplicated type B dissection a primary strategy of tailored anti-hypertensive medical treatment and serial imaging is justified, with deferred stentgraft implantation as an option for patients failing to respond to medical management.
Nienaber said that it is known the majority of deaths after hospitalisation with acute type B dissection occur within the first seven days. He added that what is not known is, after presentation, which medically treated patients are at increased risk of abrupt or accelerated deterioration (early) or developing an important complication (late) that might potentially benefit from endograft management during initial hospitalisation. He pointed that, in the IRAD registry, TEVAR improves survival in acute complicated type B dissection but that randomised data are needed for support this notion.
Dr Matthew Thompson added that EVAR of chronic dissections are technically possible but there is little data to support use in long-term, new techniques reveal alarming gap in disease definition, and longitudinal studies will define role.
ADSORB trial update
Dr Jan Brunkwall, University Hospital Cologne, Germany, presented an update on the Trial Comparing Endografting with Best Medical Treatment (BMT) for Acute Type B Aortic Dissections (ADSORB). According to Brunkwall, due to refinement of the protocol and safety issues study centres have just been initiated so that enrollment may start.
The European study is designed with 250 patients, randomised in two groups. The inclusion criteria are presence of acute (symptom onset to diagnosis ?14 days) uncomplicated type B aortic dissection. The test group (n=125) will have BMT and the Gore TAG device; the control group (n=125) will have BMT alone. The primary outcome will measure composite of false lumen thrombosis, aortic rupture, and aortic dilatation. ADSORB will have three years of follow-up, which will be evaluated by CT, chest X-ray and BP monitor.
STABLE trial update
An update on the STABLE trial (Study for Thoracic Aortic Type B Dissection using EndoLuminal Repair), conducted in the US, was presented by Dr Joseph Lombardi, Thomas Jefferson University Hospital, Philadelphia. He presented the dissection stents mode of action: maximise true lumen diameter/patency, altered false lumen flow dynamics, reduction of flap mobility, alleviates obstruction, potentially enhances false lumen thrombosis, long-term remodelling of true lumen, options for further intervention if needed.
The downside is that long-term data for metal stents in a dissected field is lacking, medium and long-term follow-up is needed and secondary/tertiary procedures may be needed to achieve goals. One of the conclusions is that petticoat concept for type B aortic dissection has advantages for patients with persistent obstruction after primary entry point coverage.
The STABLE trial uses the Zenith Dissection Endovascular System, from Cook.