Michael Dake, Stanford, USA, outlined the first experiences with the Gore TAG (W L Gore) thoracic branch endoprosthesis and Frank R Arko, Charlotte, USA, presented on the MONA LSA (Medtronic) branched device results at a session yesterday. Both speakers shared early cases and their results.
Thoracic aortic aneurysms that involve the left subclavian artery often leave physicians no choice but to use surgical techniques or to cover the branch vessel. “Although reports from single-centre experience with the hybrid approach have been positive, a single branch thoracic endograft specifically designed for treatment of the aortic arch (Zone 0–2) could be useful in extending the advantages of endovascular repair to the aortic arch. As such, the Gore TAG Thoracic Branch Endoprosthesis is designed as a modular system which allows for treatment of aortic arch pathologies using a less invasive hybrid endovascular approach,” Dake said.
He presented on the Zone 2 US investigational device exemption feasibility trial that will enrol 20 to 40 patients at six sites. Patients will be followed for five years. The study will evaluate the device for the treatment zone 2 aneurysms.
The Gore TAG thoracic branch endoprosthesis has a modular construction design with off-the-shelf components. It has an inner lumen for anchoring and sealing the branch component. The complete system consists of aortic and branch components designed for the use in the arch, and also the accompanying accessory devices to facilitate delivery.
“The system is easy to use with a single femoral access and requires minimal catheter manoeuvres. It is safe with zero ischaemic time and has low risk of branch vessel coverage. After the first four cases, successful access and deployment of the endoprosthesis was seen in all cases. There was one procedural type 1 endoleak that resolved without re-intervention at one month. There were no device-related endoleaks, but one type 2 endoleak was seen at one month. There were no deaths or neurological events. There were no site reported serious adverse events related to the device,” he said.
Dake explained that the procedure to deploy the device included inserting the guidewires in aorta and branch vessel; introducing the aortic component over both guidewires into position within the arch; deploying aortic component and withdrawing catheter; advancing the introducer sheath and dilator and advancing and deploying branch component.
In order to be enrolled, patients had to have descending thoracic aortic aneurysms requiring placement of the proximal extent of the aortic stent graft in Zone 2. The primary endpoints of the study were: successful access and deployment of the thoracic branched endograft and the primary patency of the side branch assessed by angiography when the procedure finishes. The secondary endpoints included a one-month core lab analysis, assessing the side branch primary patency and device-related endoleaks.
Arko told delegates that there was a clinical need for left subclavian artery preservation in association with encroaching thoracic artery aneurysm. He presented the current status of an early feasibility trial in the FDA’s new innovation pathway testing the Valiant Mona LSA device.
The key goals of the trial are to validate the procedure in humans; assess the safety and performance acutely and at 30 days and collect imaging data to augment the current understanding.
Arko told delegates that the Valiant Mona LSA Thoracic Stent Graft consisted of a flexible cuff “volcano” on the main body. The system is a two-graft system and the main graft system comes in diameters between 30 and 46mm and in the single length of 15cm. It is a two-wire system as well and the secondary wire can be snared and then the second branch is brought up and deployed. The branch graft itself is made of a nitinol helical wire and polyester fabric. It has a proximal flare. The branch graft is always 40mm in length and a 15F profile, femoral access system.
The early feasibility trial is a prospective, non-randomised, three-centre, premarket clinical study that has enrolled nine patients. The primary safety and effectiveness objectives were measured acutely and at 30 days. “The follow-up schedule will be at 0-30 days, six months, 12 months and annually through five years,” Arko said.
The principal investigators are Eric E Roselli, Cleveland, USA, Frank R Arko, Charlotte, USA and Matt Thompson, London, UK.
Arko revealed that the current status of the early feasibility trial had seven patients enrolled as part of the US cohort and two enrolled as part of the cohort outside the US. One emergent case had been enrolled in the USA, outside of trial. Acute procedure results from all seven patients revealed 100% technical success and 100% patency in both main and branch stent graft. There were no type I or III endoleaks.
“All current devices need a healthy landing zone to seal. To achieve sufficient landing zone, the left subclavian artery may be sacrificed with resulting complications, such as 6% arm ischaemia, 4% spinal cord ischaemia, 2% vertebrobasilar ischaemia, 5% anterior circulation stroke and 6% death. Left subclavian artery preservation is recommended in the literature. 17–43% of patients undergoing TEVAR have planned coverage of the left subclavian artery to achieve an adequate proximal seal and the coverage of the left subclavian artery without revascularisation is the single most important predictor of post-TEVAR stroke,” Arko said.
