TEVAR Therapy of Thoracic Aortic Pathologies

Blog

Submitted on Fri, 08/11/2017 - 11:17

by Frank J. Criado, MD, FACS, FSVM

The long CX session on Thoracic Pathologies and TEVAR started with Stephan Haulon (Lille, France) and his overall state-of-the-art summation: “The clinical applications of endografts go beyond aortic aneurysmal disease. Although most of our studies and devices have focused on aneurysms, pretty much all that we will talk about today is applicable to the entire spectrum of aortic diseases—aneurysms, dissections, intramural hematoma (IMH), penetrating ulcers (PAU), and trauma,” he said. Acute aortic syndrome could result from aortic dissection, intramural hematoma, or a penetrating ulcer.

Aortic dissection is the most common aortic emergency seen in 10 to 15 cases per 100,000 adults/year. Of these, two-thirds of cases are type A and one-third is type B. In the acute type B, 30% are complicated and 70% uncomplicated. In addition, 1/8 patients with aortic dissection have IMH or PAU.

Haulon went on to state that asymptomatic IMH may show resolution in 50% to 80% of cases. Thicker hematomas are much likelier to progress and need frequent re-imaging. Symptomatic IMH patients are associated with a 33% rupture risk and are most likely treated with TEVAR today. For PAU in need of treatment, “simple” TEVAR may be the answer.

“For acute type B dissection (TBAD), intervention is generally reserved for symptoms such as malperfusion of end-organs; rupture; impending rupture (rapid expansion); and persistent pain and hypertension. The goals of TEVAR are coverage of primary tear, decreased pressure in the false lumen, re-pressurization of true lumen, reperfusion of branch vessels, and thrombosis of false lumen,” explained Haulon while explaining the treatment for acute dissection.

Which patients with “uncomplicated” TBAD should we treat? “We need to try to predict progression,” said Haulon. “The timing of repair of uncomplicated dissections suggests that severe complications are more common in the acute and delayed acute (p=0.04) phase and that delayed intervention lowers the risk,” he clarified.

Haulon noted that once the dissection progresses to chronic phase, 50% of patients rupture or require repair within 4 years. False lumen growth averages 3 mm/year. TEVAR for chronic dissections results in 20% re-intervention for persistent sac growth. In such cases, direct false lumen occlusion using the candy plug technique, or knickerbocker technique, has been suggested.

For chronic dissections, treatment is tailored to age, genetic disorder, clinical risk, and anatomy. “It is logical to assume that the benefits of endovascular therapy will be even greater when this is applied to more challenging anatomy, given that more extensive dissection, higher clamp site, visceral ischemia, and reconstruction are all factors associated with increased morbidity,” he said.

With regard to aneurysmal disease, TEVAR is first-line strategy that has produced excellent immediate outcomes. High-risk patients may have poor long-term outcomes that are not related to the aortic disease.

Haulon also touched on aortic injury, including injuries from trauma and other conditions such as aorto-bronchial fistulas and mycotic aneurysms. He outlined individual treatment strategies for each condition. TEVAR is the first-line therapy in specific cases, with specific devices. As the majority of these patients are acute cases, the most promising results are achieved with a 24/7 aortic team, he said.

Ascending aorta

Rodney A. White (Long Beach CA, USA) presented on ascending aortic remodeling for various pathologies. He spoke on a feasibility study set out to evaluate the Medtronic Valiant thoracic stent-graft for the treatment of ascending thoracic lesions with preserved “tubular” aortic anatomy (non-aneurysmal). He reported that preliminary evaluation to date demonstrates accurate deployment, secure fixation, and no migration. The study is being conducted under the auspices of a physician-sponsored IDE approved by the FDA. All procedures are performed in a hybrid operating room suite, which White regards as critically important for these developments.

White further emphasized that, at this point in time, the FDA is eager to see evidence in support of the physical/mechanical stability of endografts placed in the ascending aorta alone before evaluating more complex platforms.

In response to the concept that disease in the ascending aorta and the arch can be treated by endovascular means, the audience was asked to vote on the statement “total aortic endovascular repair beats open surgery hands down,” debated by Timothy Resch (Malmö, Sweden), and Heinz Jakob (Essen, Germany). Seventy-two percent of the audience backed Jakob, voting against the motion. Jakob first outlined the goals of aortic intervention, which are to avoid the risk of rupture (for dissections and aneurysms); restore the true lumen perfusion and resolve malperfusion (in cases of dissection); warrant the durability of aortic restoration (for both dissection and aneurysms); and prepare easily accessible segments to facilitate secondary intervention. He called endovascular repair beyond the descending aorta “a brave new world”. He argued that the motion was incorrect, as endovascular repair is currently in the early phase of application in selected centers that have a high level of experience in a highly selected patient population. Today, open repair beats endovascular repair, but in the future, both will work together closely.

Descending thoracic aorta

In another debate, 72% of the audience voted their support for the Stanford Classification of Aortic Dissection (proposed in 1970).

On the motion “For dissecting thoracic aneurysm terms type A and B are no longer satisfactory” Tilo Kölbel (Hamburg, Germany), who spoke against it, said: “The Stanford classification simplified the thoracic aortic dissection patients into 2 types: A and B. This new classification met the clinical need for the urgent triage in patients presenting with aortic dissection. Type A patients need surgery, and patients with type B dissection are generally in need of less urgent intervention and can be managed medically, unless presenting with complications.”

He further added: “The important value of this initial classification according to the Stanford system is unchanged, as it allows every physician to make the initial most important life-saving decision about where the patient should be directed: to the operating room (type A patients) or to the intensive care unit (type B patients).”

However, Dittmar Böckler (Heidelberg, Germany) had a different view. Speaking for the motion, he asserted: “It is time to adapt the Stanford classification—it is no longer satisfactory.” He noted that contemporary treatment of aortic dissections was influenced by 2 fundamental, major developments: the International Registry of Acute Aortic Dissection (IRAD), and endovascular therapy for aortic dissection with the introduction of stent grafting by Michael Dake, Christoph Nienaber, and others. Böckler then made the point that therapy for aortic dissection has become varied and multimodal for both type A and B. “There are also variants of aortic dissection that are unable to be assigned within the Stanford classification, and anatomical differentiation should not decide where the patient goes. Treatment of dissection should be organized within interdisciplinary teams. The terms type A and B have been helpful for decades, but are not up to date anymore if we want to apply new knowledge and tools in an innovative changing medical environment,” he concluded.

Joseph Lombardi (Camden NJ, USA) then told the audience that “complicated means complicated” and implies that there is a need to consider urgent intervention for these patients. He presented on the STABLE trial (using the Zenith endograft, Cook Medical) and noted that the data from both STABLE I and II show a low 30-day mortality and paraplegia rates with TEVAR. There is still a risk of disease progression, which requires close surveillance and re-intervention as needed. “Bare stent management can be advantageous in early- and long-term presentations and management of complicated type B aortic dissection is a long-term commitment,” he said.

Uncomplicated chronic type B dissections

Speaking on the natural history and predictors of chronic type B dissection, Böckler commented that there were few long-term data on the natural history of these dissections. There appears to be an 80% to 90% mid- and long-term survival with best medical therapy. The annual aortic expansion rate is around 1 to 2 mm in diameter per year. Böckler said: “Data from randomized controlled trials shows that remodeling is better after TEVAR, but there is no proven survival benefit in the long term as yet. There are also image-based predictors for progression that have been defined.” He concluded that with regard to aortic-related mortality, the natural history in the chronic phase is relatively benign. “Recent guidelines still recommend best medical therapy for uncomplicated acute type B dissection. Nevertheless, there is a trend towards early intervention in patients at higher risk for aortic expansion based on the predictors of expansion,” he said.

Kölbel then presented a disease-specific approach for acute, subacute, and chronic uncomplicated type B dissection. “Aortic dissection requires custom-made treatment strategies. Tubular stent grafts are sufficient in the majority of cases of type B aortic dissection. There is a need for advanced techniques in the acute and chronic settings. Access, choice of landing site, and false lumen occlusion require planning, sound endovascular skills, and a large variety of devices,” Kölbel explained.

In the end, 92% of the CX audience backed the idea that a disease-specific approach should be adopted for acute, subacute, and chronic uncomplicated type B dissection.

Jean-Marc Alsac, Paris, France, then spoke about a technique to stabilize and obliterate the false lumen, making the point that closure of the proximal tear is efficient but not always sufficient. The STABILISE (Stent-assisted balloon-induced intimal disruption and relamination in aortic dissection repair) approach, he said, is a feasible endovascular technique that shows promise to achieve repair of the dissected aorta by inducing complete false lumen obliteration.

His experience with 52 patients showed no late adverse events and no aortic ruptures, stent migration, intimal flap erosion, or re-dissection. Alsac added that the technique is efficient to treat acute complications and seems to prevent aneurysmal progression, with a low reintervention rate. “The restoration of uni-luminal flow in the thoraco-abdominal aorta has the potential to improve long-term outcomes. “Prospective, multicenter investigations are required to implement this strategy more broadly and to define the best indications and timing for such an aggressive therapeutic option,” he said.

When asked to vote on the treatment they would favor for uncomplicated chronic type B dissection, 14% of the audience chose fenestrated or branched endografting; 8% elected to plug the false lumen; and 78% said they would avoid any intervention if the patient was stable.