Critical issues in endovascular stent grafting

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The 11th international symposium concerning ‘Critical Issues in endovascular stent grafting’, took place in Groningen, The Netherlands, between May 31 and June 2, 2007. The meeting began with a series of live cases in which the controversies and issues surrounding fenestrated stent grafting were debated.

The symposium then highlighted current concerns regarding critical limb ischaemia (CLI). Dr John Anderson’s overview on CLI was particularly interesting, in which he concluded that curing restenosis for simple lesions in the calf was possible with drug-eluting stents. Professor Jim Reekers reviewed recent CLI studies and stated that there was no scientific data to prove that stents improved patency and therefore concluded that there was little clear evidence to prove that stents below the knee improve clinical outcomes.

Next, Dr Marc Bosiers outlined why surgeons should treat patients with CLI and pointed out that at a diagnosis level patients are almost always referred to vascular surgeons. Furthermore, vascular surgeons could make an unbiased opinion of possible treatment options, which could be surgical, endovascular or hybrid. Finally, Bosiers stated that it was the vascular surgeon who was capable of close monitoring and early intervention, if required.

Carotid artery stenting

The subsequent session discussed the critical issues surrounding carotid stenting. After Giorgio Biasi explained when it should be possible to stent a carotid artery, Bosiers examined which stent to use in symptomatic patients. “Stents with a small free cell area is the direction most stent manufacturers are moving towards,” Bosiers stated, adding that stents with better scaffolding were a positive move but nevertheless, he cautioned that carotid stenting has been pushed too far by industry. He also warned that carotid stenting should not be pushed too strongly until there is more experience in the area, as centres with the most experience clearly have better results than those that have less.

Dr Pergorgio Cao followed with his views on carotid stenting. He showed results from his centre demonstrating a major complication rate of less than 2%. He believed that advances in technical expertise, knowledge of technical progress and optimal imaging technology were essential to improve outcomes.

Clark Zeebregts who works at the UMCG in Groningen looked at the interpretation of the latest carotid trials with EVA-3S and SPACE undergoing special scrutiny. Although, in his opinion, both studies came out more for carotid endarterectomy, he pointed out that operator experience in both studies was, on average, very low and in SPACE only 26.6% of cases had embolic protection devices used, compared to 91% in the EVA-3S trial. Another relevant point was that both studies did not meet recruitment targets. He also criticised incomplete stratification, timing and plaque morphology data. Nevertheless, he was of the belief that stenting should be used with symptomatic patients at high-risk from surgery. He concluded that more clinical trial results would enable a consensus to be achieved on this controversial area.

Professor Matt Thompson concluded the session with his view on the debate. He felt that quick timing of the procedure was a far more important issue than whether to do surgery or stenting and that this was the real issue in the area, not what type of procedure to use. This is particularly relevant as the differences between the two area were not particularly significant in statistical terms.

EVAR

The first session on the Friday morning was dedicated to endovascular aneurysm repair (EVAR) of abdominal aortic aneurysms (AAA). Professor Nick Cheshire believed that EVAR can treat patients more safely but reiterated concerns about costs and long-term mortality even though he was convinced the additional costs were worth paying. Professor Janet Powell presented an age-based sub-analysis of EVAR 1. She showed that fitter patients benefited most from EVAR and stated that there was no evidence that open repair was better for fitter patients. She warned the audience that graft rupture could become a significant long-term complication, but at this stage could not be sure.

Patrick Peeters followed with an explanation of the complicated reimbursement situation in Belgium. He informed the audience that there was a situation where conflicting studies were acting as a brake on full scale reimbursement but that Belgian EUROSTAR trial was allowing limited use of stent grafts at present.

The day ended with a session on new developments in the endovascular stent grafting arena. Hence Verhagen, University Hospital, Utrecht, announced the formation of a clinical trial for the new Medtronic AAA stent graft, which will comprise four German and three Dutch centres and will take place in autumn of 2007. Furthermore, he explained the new AAA stent graft was specifically (but not exclusively) designed for short angulated necks and challenging anatomies in the iliacs. Verhagen also said that animal and cadaver testing had been completely successful up to this point.

Willem Wisslink’s discussion on treatment options for AAAs rather than open surgery or EVAR to be of interest, discussing the merits of laparoscopic surgery. He disclosed that he performs laparoscopic surgery in tandem with endovascular repair and open surgery. He believes it is a valid option that needs more research and clinical trials to determine its true worth.

On Saturday morning the focus of the meeting moved to emergency EVAR. Chee Soong, Belfast, UK, looked at the experience in his centre. He felt that EVAR had been used too often in unsuitable patients and that initial success had influenced selection. He added that he was less inclined to exceed neck and iliac limits and warned the audience not to be over ambitious.

rAAAs

Dr Mario Lachat then presented his single-centre data regarding ruptured AAAs (rAAAs), and examined when to perform an open repair, when to use EVAR and when to employ the hybrid procedure, based on his ten year experience at the Zurich University Hospital (ZUH). Between 1997-2007, there were 1,027 AAA repairs at ZUH. Of these, 431 required open repair and 596 EVAR. In total, there were 210 rAAAs, with 125 patients receiving an open repair and 85 receiving an EVAR.

The 30-day mortality for the open repair patients was 33%, compared with a 30-day mortality of 12% for EVAR patients. The combined 30-day mortality was 22.5%. Lachat reported that the absolute risk reduction for ER/OR was 21%, with a relative risk reduction for ER/OR rate of 36%. The absolute risk reduction for all/OR was 10.5% and the relative risk reduction for all/OR was 32%.

Lachat recommended endovascular repair whenever possible, as long as the operator had the necessary skills and the sufficient logistics were in place. He suggested that open repairs should only be performed in case of missing neck or where access proves impossible.

Concerning devices, Lachat said that in his experience branched stent grafts should be used routinely, although aortouniiliac grafts allow less experienced teams to treat rAAA by EVAR and extend the treatment to patients with unilateral iliac stenosis or occlusion.

He concluded that EVAR of rAAA has helped to reduce the mortality rate of rAAA, but he warned that the results can be improved, by increasing pre- and perioperative management.

Cost effectiveness

Following Lachat was Ignace Tielliu, Groningen, who showed figures from his centre showing that EVAR was cheaper in per procedure terms and that the survival rate was 13% higher. He did warn the audience that there was danger of bias as the control group was historical and the EVAR subset only 49 patients. He concluded that using EVAR as an option was a more cost effective option than open surgery only.

Jacob Buth ended the session by arguing in favour of the regionalisation of patients with acute AAA disease. He said that they should be reserved for regional vascular units with an adequate volume of elective and emergency cases.

The conference ended with sessions on critical issues for pararenal and thoraco-abdominal aortic aneurysms, critical issues in thoracic stent grafting and type B dissections. Next year, ‘Critical Issues’ will take place in Cologne, Germany.