In traditional Charing Cross fashion, yesterday’s debates stirred much discussion in the Main Auditorium. Particularly stirring was the debate where the audience voted 70% against the motion that EVAR is not sensible for any abdominal aortic aneurysm with a neck length less than 10mm. Stephen Cheng (Hong Kong) spoke for the motion, while Jan Blankensteijn (Amsterdam, Netherlands) sounded-off against the motion.

Making his case, Cheng said that even with new devices, there are more early complications, more late complications, more (difficult) secondary interventions and more adjuncts associated with short-neck endovascular aneurysm repair.

On the other hand, his opponent maintained that in selected cases of infrarenal neck length <10mm, “Any of the current infra/transrenal devices can be used with or without endoanchors for enhancement,” adding that even if it comes with a moderately increased risk of type 1a endoleak, it “balances against downsides of F-EVAR, CHIMPS, or against open repair (if F-EVAR is not an option).”

Discussing the outcome of the debate and the audience’s strong position against the motion, Blankensteijn said, “I think that people understand that things are not absolute and clearly we know that staying inside IFU you get better results. I am not running around proposing to treat any less than 10mm neck with an infrarenal device, but the point is that judicious use of these devices outside IFU can produce better results and injudicious use outside the IFU is an instruction that the industry gives you, we need to think with these device what to do an there are several occasions it does not make sense or it may even be dangerous to use a fenestrated stent graft. Then I would suppose that an infrarenal device (for instance Gore Excluder) preserves all the options juxtarenally, so if this fails, you still have the option to use a fenestrated cuff or go higher up.”

The debate took place during a session on procedures for infrarenal abdominal aortic neck.

The answer lies in the neck

While presenting the morphology findings from the IMPROVE trial, Robert Hinchliffe, London, UK, drew attention to independent association between neck length and mortality. “Only aortic neck length is significantly associated (inversely) with 30-day mortality both for open repair (p<0.001) and overall (p=0.007). The shorter the neck, the higher the mortality after open repair (and EVAR). With long necks, the 30-day mortality from EVAR and open repair is similar (and this is consistent with the results of the AJAX and ECAR trials),” he said.

Therefore, added Hinchliffe, a short aneurysm neck was the commonest reason for a patient being unsuitable for conventional EVAR. The results also explain why observational studies, which cherry pick long-necked aneurysms for EVAR leaving all the short necked aneurysms for open repair, always show that mortality is lower after EVAR. “Such observational studies are comparing apples and oranges,” he said.

The morphology findings could also explain the worse outcomes in women as short aneurysm necks are especially common in women.

“In the future, new, widely available endovascular strategies for rupture in short necked aneurysms are needed and results following rupture should report juxta-renal and infra-renal aneurysms separately,” Hinchliffe said.

“Aneurysm morphology indicates whether a patient with ruptured abdominal aortic aneurysm is eligible for EVAR and may influence the outcome of both EVAR and open surgical repair,” he concluded.

Stick to the IFU

Timothy Resch, Malmö, Sweden, enforced the point that the outcome of EVAR is “excellent if we stick to the IFU and hostile sealing zone anatomy affects the outcome of EVAR negatively both in the short and long term regardless of the device that you use.”

Resch explained that 10—20% of EVAR patients have necks <15mm, and these short infrarenal necks are predictive of initial technical failure, with increased incidence of early and late type 1 endoleak and increased use of intraoperative adjunctive procedures, where the long-term outcome is impaired and endoleaks, migration and late rupture are common.

Referring to a contemporary meta-analysis of 12,000 patients treated with modern devices, 3,039 patients with hostile necks saw an increase in 30-day mortality, intraoperative adjuncts, 30-day migration and an increase in type 1 endoleak at 30 days and one year.

Further, in the ANCHOR registry, Resch noted, a regression and ROC analysis was used to try to find predictive factors for type 1a endoleak which showed that the diameter of the neck correlates with poor outcome, as does the anatomic neck length. “This actually provides some solid data for calculating the risk in the individual patient,” he said.

“So one option of course in these short juxta pararenal aneurysms is to seal higher above and use the fenestrated and incorporate the visceral arteries in your repair. Does that solve the problem of the proximal endoleaks? Again, it depends on how you use the graft,” Resch suggested.

Making a case from some of his own data and that of a study at the Cleveland Clinic, USA. “We found no cases with proximal type 1 endoleaks during long-term follow-up of these patients. So maybe this is the solution for everything—using it in the right context. In a larger series from the Cleveland Clinic analysing over 900 patients with fenestrated grafts, indeed there was a 2.8% incidence of late type 1a endoleak occurring in a steady fashion over time and almost half after a year post-operatively. Looking at the risk factor in that series, what they identified again was a poor sealing zone, just as you would in an infrarenal neck and more that 10% was diameter change and they also found that the sealing zone was much more unstable in the juxtarenal vs. more proximal aorta. So from the clinical perspective, we have learned from that and we now place more fenestrations on the graft to reach a healthy sealing zone, which in our series, combined with the series from Lille with 300 patients, resulted in a higher placement of the endograft than we initially did without affecting the operative mortality or the one-year outcome,” he reported.