Scallops May Offer a Simple Alternative to Branched Devices in the Arch

(Leipzig, Germany) January 30, 2020 -- Results of the first European prospective, multicenter clinical study of the use of a proximal scallop endograft that accommodates the supraaortic trunks¹ were presented by Jean-Marc Alsac, MD (Hôpital Européen Georges Pompidou, AP-HP Centre Université de Paris INSERM, France).

The presentation takes place during a session on pioneering techniques for pathologies of the ascending aorta and the aortic arch.

The scalloped Relay stent graft, custom-made by Terumo Aortic [formerly made by Bolton Medical], is intended to simplify the treatment of aortic disease involving the arch. The scallop itself represents a single fenestration that encompasses the supraaortic branches.

“The concept of the scallop is to make things more simple when possible in the arch,” Dr Alsac said. “With just one large fenestration, there is no need to catheterize or cannulate the supraaortic trunks. This limits the risk of stroke compared to a more invasive and demanding branched device.”

The Relay stent graft is composed of self-expanding nitinol springs, stacked in a tubular configuration and sutured onto a polyester vascular graft with a bare stent proximal clasping. The scallop effectively extends the proximal landing zone along the inner curvature of the arch, while preserving the patency of supraaortic vessels. The delivery system on the basis of the Relay Plus is oriented on a pre-curved nitinol catheter, orienting the scallop systematically on the upper side of the aortic arch. Multiple small radiopaque markers demarcate the position of the scallop as well as the ends of the graft itself.²

Lesions involving the supraaortic branches can currently be approached in a number of ways, explained Dr Alsac. Debranching or parallel grafting may be carried out in emergent cases, where the time required to produce a custom-made graft is not permitting.

He also noted a number of branched devices currently on the market. The Gore TAG Thoracic Branch Endoprosthesis (W.L. Gore and Associates), which has completed feasibility study^3,4 and is now in its pivotal trial phase, includes a single side branch and an optional aortic extender cuff. The Nexus (Israel) is another single branch graft, which last year received the CE Mark and is available off the shelf; its two-year results were presented at VIVA last November.⁵

The Valiant Mona LSA Thoracic Stent Graft System (Medtronic) also possesses a single branch and is based on the Valiant thoracic stent graft platform. Multibranch devices include the Terumo Aortic Relay Branch thoracic stent graft, which possesses a proximal landing zone in the proximal aorta and branch grafts that extend into the innominate and left common carotid arteries; this devices is in early feasibility study.⁶ Another double inner branch graft is the Arch Branched graft (Cook Medical), with international multicenter data emerging from three high volume centers^7,8, and more recently single-center experience from Hamburg.⁹

Summarizing the data relating to branched arch devices, Dr Alsac said, “From the experiences of different centers using these branched devices, we have learned that the morbidity, and specifically cerebrovascular adverse events, are very high with such devices. These different devices already have some literature, which shows that the rate of stroke during these procedures are high, from 11-20%, depending on the different devices that have been studied.”

He added that the use of such risky and complex devices may be avoided, particularly in cases where pathology does not involve the ostia of the supraaortic trunks. “The proximal scallop is as easy to deploy as a regular stent graft,” he stressed. “There is no cannulation in the arch, no snaring of wires in the arch. The graft self-orientates by the nitinol pre-curved inner catheter, tracking to the natural curvature of the arch. We also don’t need to cross the aortic valve – there is no need for rapid pacing during deployment. These are all the points that make the deployment of the graft easier and probably safer. That is what we wanted to demonstrate in this study.”

He added that branched devices should be the preserve of selective, high-volume centers, where lower stroke rates can be achieved. In less experienced centers, he said, the scalloped device offers, when feasible, a more accessible alternative to branched devices, it being as simple as a standard graft and thus allowing for broader access to arch treatment without impacting stroke risk.

Today, Dr Alsac presents results of the Relay Echancrées Proximales (Relay Proximal Scallop; REP) study, a safety and efficacy analysis of the Relay Proximal Scallop carried out via the Terumo Aortic custom-made program outside the US, for the treatment of non-septic, acquired disease of descending thoracic aorta located close to supraaortic trunks. Conducted in 10 centers in France, the study included 40 patients treated between January 2015 and May 2018.

Patients were of a mean age of 71 years. Two-thirds of patients had atherosclerotic aneurysms carrying a high risk of stroke. There were also eight chronic aortic dissections, and four type 1A endoleaks from previous TEVAR. “These were patients who were not good candidates for open repair,” commented Dr Alsac. “These are usually patients where either you would go for a debranching of the supraaortic trunks, or a double-branch device.”

The study’s primary endpoint was cumulative morbidity and mortality, including all-cause death, stroke, transient ischemic attack (TIA), and paraplegia. Patients were followed up at 30 days, six months and one year. Most centers included in the study implanted two stent grafts, noted Dr Alsac, and as such this study represented the device’s learning curve. “Most of these cases were performed without any expert proctoring. The idea was to reflect the very early, real-world  experience. That is why most of these grafts were put in the hands of surgeons who had never treated an arch with such a device.

“Another important point in this study is that the targeted proximal sealing zones in the arch were, in two-thirds of cases, in zone 1 and zone 0 – so these are real lesions in the arch, not just descending thoracic lesions that require coverage of the subclavian artery. Also, two-thirds of the patients’ aneurysms were atherosclerotic, fusiform or saccular, and these are the lesions that are more at risk for stroke in all studies in the literature.”

Successful implantation was achieved in 97% of cases. Cervical debranching was carried out in 34% of cases, including seven right common carotid to left common carotid artery bypasses, and ten left common carotid to left subclavian bypasses. Mean procedural time was 170 minutes: “This was short, especially considering that these cases were performed as a learning curve in most of the centers,” commented Dr Alsac, adding that there were no unexpected supraaortic trunk occlusions, conversions to open repair, or retrograde aortic dissections.

At one-month post procedure, mortality was 10%, including an in-hospital mortality of 5%. No strokes occurred in this period, although two TIAs were recorded (5%). No disabling stroke occurred during the postoperative course. Endoleaks occurred at a rate of 24% (n=8), including two type Ia, two type II and one type III, although no aneurysm growth or rupture occurred. At one year, all-cause mortality was 17.5% (n=7), with no incidence of stroke and three TIAs (n=3). Patency of all targeted supraaortic trunks was maintained at one year, with no occurrence of stent migration. Lesions remained stable or decreased in diameter in 97% of cases, with no aneurysmal rupture. A single patient had an increase in lesion diameter, due to a type 1A endoleak.

Speaking of previous studies investigating the use of scalloped arch grafts, Dr Alsac noted: “The team of Dr Hamady in London have a big experience with this graft.^10,11 In the literature, there are a total of five papers about this topic, mostly European papers, and all single center experiences and retrospective studies.^2,10-14”

In his concluding remarks, Dr Alsac touched upon the notion of physician-modified grafts, explained his reservations: “I don’t have experience with physician modifications, which are made on the basis of the Valiant stent graft. But, like most physicians, I would fear degrading the material, and having long-term problems with tearing of material due to these modifications. I prefer to use grafts that have been custom-made by the companies, that preserve the solidity of the materials.”

And while scalloped devices used in the REP study required up to three weeks to each be custom-produced by the manufacturer, Dr Alsac noted that there may be sufficient justification for an off-the-shelf version: “In our experience, we have shown that 95% of the cases could have been treated with a predesigned scallop of 20 by 30 mm. The design of the scallop is much easier to perform than fenestrations, so we could imagine having this scalloped stent graft as an off-the-shelf device by Terumo. The proximal component could be an extension of their products.

“In fact, the idea of this study was to encourage the company to go through this process. We have been talking about this for about eight years, and now I feel that they are more and more conscious that single- and double-branch devices carry a very high risk of stroke, and that this is probably not the way to go for most patients. But this is of course an industry choice; hopefully, we are leading them in this direction to create an off-the-shelf device.”

References

1. Study of the Relay Pro® Thoracic Stent-Graft in Subjects With Traumatic Injury of the Descending Thoracic Aorta. ClinicalTrials.gov. Available online at https://clinicaltrials.gov/ct2/show/NCT03090230. Accessed January 30, 2020.
2. Fernández-Alonso L, Fernández Alonso S, Martínez Aguilar E, et al. Endovascular Treatment of Aortic Arch Lesions Using Scalloped Endografts. Vasc Endovasc Surg. 2017;52(1):22–6.
3. Feasibility Study for GORE® TAG® Thoracic Branch Endoprosthesis to Treat Proximal Descending Thoracic Aortic Aneurysms. ClinicalTrials.gov. Available online at https://clinicaltrials.gov/ct2/show/NCT02021812. Accessed January 30, 2020.
4. Patel HJ, Dake MD, Bavaria JE, et al. Branched endovascular therapy of the distal aortic arch: preliminary results of the feasibility multicenter trial of the gore thoracic branch endoprosthesis. Ann Thorac Surg. 2016;102:1190-1198.
5. [News article] VIVA 2019: Nexus stent graft demonstrates promising mid-term results. Vascular News. 2019 Nov 5. Available online at https://vascularnews.com/nexus-stent-graft-demonstrates-promising-mid-term-results. Accessed January 30, 2020.
6. Early Feasibility Study of the RelayBranch Thoracic Stent-Graft System (RelayBranch). ClinicalTrials.gov. Available online at https://clinicaltrials.gov/ct2/show/NCT03214601. Accessed January 30, 2020.
7. Haulon S, Greenberg RK, Spear RJ, et al. Global experience with an inner branched arch endograft. Thorac Cardiovasc Surg. 2014;148(4):1709-1716.
8. Spear R, Haulon S, Ohki T, et al. Editor's Choice - Subsequent Results for Arch Aneurysm Repair with Inner Branched Endografts. Eur J Vasc Endovasc Surg. 2016;51(3):380-385.
9. Tsilimparis N, Detter C, Law Y, et al. Single-center experience with an inner branched arch endograft. J Vasc Surg. 2019;69(4):977-985.e1.
10. Alsafi A, Bicknell CD, Rudarakanchana N, et al. Endovascular treatment of thoracic aortic aneurysms with a short proximal landing zone using scalloped endografts. J Vasc Surg. 2014;60(6):1499-1506.
11. Hanna L, Gibbs R, Fadl A, et al. AAA 31. Midterm to Long-term Outcomes of Scallop Endografts in the Management of Aortic Disease With Unfavorable Proximal Landing Zone in the Arch. J Vasc Surg. 2019; 70(5):e145.
12. Oliveira-Pinto J, Sousa J, Rocha-Neves J, et al. Endovascular Solutions for Thoracic Aortic Aneurysms with Challenging Anatomies. Rev Port Cir Cardiotorac Vasc. 2017;24(3-4):113.
13. Ben Abdallah I, El Batti S, Sapoval M, et al. Proximal Scallop in Thoracic Endovascular Aortic Aneurysm Repair to Overcome Neck Issues in the Arch. Eur J Vasc Endovasc Surg. 2016 Mar;51(3):343-349.
14. van der Weijde E, Bakker OJ, Tielliu IF, et al. Results From a Nationwide Registry on Scalloped Thoracic Stent-Grafts for Short Landing Zones. J Endovasc Ther. 2017;24(1):97-106.