The CX Great Debate saw Peter Taylor, London, UK, and Richard Gibbs, Imperial College, London, UK, persuaded 71% of the audience at the Charing Cross International Symposium yesterday to vote for their position against the motion “For uncomplicated type B dissections, early intervention is indicated”.

Their opponents in the debate, Christoph Nienaber, Rostock, Germany, and Jan Brunkwall, Köln, Germany, had the support of 29% of the audience. Audience discussion at the end of the session identified a need for a larger randomised trial with long-term follow-up that had clinically meaningful endpoints.

Nienaber and Brunkwall set out to persuade the audience that placing a stent graft early was important in order to heal the aorta. “Rupture, malperfusion, hypertension and down the line, aneurysm formation are some of the risks of type B dissection,” Brunkwall said.

Nienaber made the point that scaffolding was the only way to stabilise the progression of the dissection as data available so far showed that the disease is characterised by a downhill evolution over time. “If there is no scaffold, and the aorta is not remodelled, you are confronted with ongoing attrition rate in terms of cardiovascular death and progression of the disease. This is beneficial for even in so called stable or clinically silent patients,” he said. He made his views clear that no dissection was ever uncomplicated.

“Only pre-emptive stenting will ensure long-term remodelling and stability. Only remodelling stabilises the aorta and no drug that induces remodelling, only the likelihood of rupture, so supportive scaffolding should be offered to any type B dissection,” Nienaber said.

“What do we achieve with TEVAR in the setting of type B acute dissections? Fewer later interventions and lower mortality after five years,” Brunkwall said. The five-year long-term follow-up of the INSTEAD XL showed a statistically significant reduction in aorta-specific mortality and a statistically significant reduction in disease progression in favour of the combined TEVAR plus medical therapy arm.

Brunkwall also made the point that the ADSORB trial with false lumen thrombosis as an endpoint, had shown that patients receiving TEVAR have significantly more complete and partial thrombosis than the ones getting best medical therapy.

The ADSORB trial was a prospective randomised trial to compare TEVAR with best medical therapy in patients with acute uncomplicated type B aortic dissection. At the follow-up for one year, there was no death stroke or paraplegia in either group at 30 days and aortic remodelling at one year favoured the intervention but it did not reach statistical significance.

Taylor and Gibbs based their arguments around the fact that medical treatment is getting better. Briggs noted that a recent study (Fattori et al. J Am Coll Cardiol 2013;61:1661-78) had shown that survival at five years without intervention is 70–89%. They also highlighted the fact that TEVAR carries risks including retrograde dissection; stroke (3%); paraplegia (2.5%) and other complications. The team stated that all current endografts used in dissection are designed for use in aneurysms.

“There is no adequate evidence to recommend early intervention in all but a few patients with uncomplicated type B dissection. Only a small subgroup at high risk of aortic expansion will benefit from early intervention and these patients can be identified using techniques such as functional imaging,” Briggs said

Taylor also attacked the quality of evidence from randomised controlled trials that supported early intervention. “The ADSORB trial had only 61 patients in total. It was underpowered and stopped at one year and was therefore too short and small to answer questions about survival and efficacy. The INSTEAD trial had only 140 patients in total and underpowered for survival. In total, there have been only 201 dissection patients ever randomised,” he said.

Taylor made the point that drug therapy was getting better and that the available evidence showed that the majority of patients are alive with medical treatment; there is 80% survival at five years and that therefore, medical treatment was safe for the majority of patients with uncomplicated type B dissection. They do not need early intervention and there is an early mortality associated with TEVAR that cannot be ignored, he said.

A member of the audience noted that in order to make a clinical difference, all-cause mortality has to be the only endpoint at five years and the trial should be designed to show superiority. Martin Bjorck, Uppsala, Sweden, also commented on the difficulty faced in every day clinical practice. “There is a problem because we know from the data from the two randomised trials that it is rather safe to do TEVAR, but that there is a 3–5% risk of  very serious neurological complications that cannot be discounted. We know from the long-term results of the INSTEAD trial that if you do not treat, you have many patients developing dilatations and needing treatment later on that is more complicated. We need a larger randomised trial with long-term follow-up.”

CX voting results

Earlier in the session, 65% of the CX audience had voted that registry data is now irrelevant and that it was time that randomised trial evidence for TEVAR dissection became available. Nearly 80% also believed that aortic intervention for acute dissection should only be performed in recognised vascular centres with cardiothoracic surgery on site.