Treatment of thoracic aortic lesions using endografts has progressed rapidly, with three manufacturers in the United States having indications for aortic aneurysms in the descending thoracic aorta that have adequate proximal and distal landing zones. Depending on the studies that were performed, some of the devices also have an indication for exclusion of penetrating ulcers. Based on the demonstrated utility of the thoracic aortic device and supported by studies that have been performed inside the United States and in international sites, adaptation of this technology to descending thoracic aortic dissections and traumatic transections is developing rapidly. Currently, it is estimated that approximately 50% of thoracic device use in the United States is for treating lesions outside of the instructions for use (IFU) indications, with the majority of these procedures being for descending thoracic aortic dissections and traumatic transections.

Because of the rapid expansion of the use of this technology, several companies have responded to the need to expand the IFU to include indications for dissections and transections. The US Food and Drug Administration (FDA) has also recognized the potential utility of these technologies and is considering innovative study options that would appropriately expedite approval of these devices if data can be captured in appropriately designed trials. As an example of this collaboration, the FDA is willing to consider data from acute complicated dissection and traumatic aortic disruption patients treated with thoracic endovascular aortic repair (TEVAR) under multiple physician-sponsored Investigational Device Exemptions (PS-IDEs) as a control, supplemented by historical reference data. The PS-IDE data that are available were collected by a multidisciplinary group of physicians (including members of the Society of Thoracic Surgeons, Society of Interventional Radiology, and Society for Vascular Surgery [SVS]) and coordinated by the SVS Outcomes Committee. The SVS outcomes data have been submitted as a Master File to the FDA and have been made available to manufacturers as a point estimate for comparison to clinical study outcomes in patient populations in which randomized studies are not feasible.1,2

In response to the need to broaden the IFU indications for TEVAR devices, Medtronic, Inc. (Minneapolis, MN) has initiated two studies in the United States that are designed to address expansion of the IFU for the latest-generation thoracic stent graft, the Valiant Thoracic Stent Graft with the Captivia Delivery System, to include treatment of patients with descending thoracic dissections and traumatic transections. The Valiant Thoracic Stent Graft's hallmark feature of high conformability meets the engineering and clinical design parameters for these new indications. The Captivia Delivery System has a deployment mechanism that controls release of the proximal FreeFlo stent until the entire length of the stent graft has been deployed. This tip-capture mechanism enhances precise positioning of the device and enables proximal device conformation to acutely angled thoracic aortic arch anatomy.

MEDTRONIC DISSECTION TRIAL
This study was designed to evaluate the clinical safety and effectiveness of the Valiant Thoracic Stent Graft with the Captivia Delivery System for the endovascular treatment of acute complicated type B dissections of the descending thoracic aorta.

The study is currently enrolling 50 to 84 subjects at up to 25 centers. The criteria for inclusion into the Medtronic Dissection Trial include patients with acute complicated descending thoracic aortic dissections admitted to the hospital within 14 days of symptom onset and treatment of the dissection within the index hospitalization. The type B Stanford classification dissections have an entry site originating in the descending thoracic aorta with the entry being at least 20 mm distal to the proposed proximal fixation site. Eligible patients must have a type B dissection that is complicated by either malperfusion as demonstrated by either visceral, renal, spinal cord, and/or lower limb ischemia, or by rupture.

The Premarket Approval Application (PMA-S) will be filed after all subjects reach 1-year postimplant, and all subjects will be followed for 5 years after the procedure.

Figure 1 shows a patient who presented with acute malperfusion treated with the Valiant Thoracic Stent Graft as part of a single-center IDE approved by the FDA.

THE RESCUE TRIAL
The RESCUE trial was designed to evaluate the clinical safety and effectiveness of the Valiant Thoracic Stent Graft with the Captivia Delivery System in the endovascular treatment of blunt thoracic aortic injury in adult patients. The study is enrolling 50 patients in up to 25 sites. Patients will be followed to 5 years, but a PMA-S will be filed after all subjects have reached 30-day postimplant. The emphasis in this study is to evaluate what appears to be a clear trend indicating lower morbidity and mortality rates in patients with traumatic aortic injury treated with TEVAR. The intent is to obtain not only procedural success rates but also longer-term follow-up to record secondary complications related to the devices in a younger population of trauma victims. Figure 2 shows an acute traumatic aortic disruption that was treated using the Valiant Thoracic Stent Graft that was enrolled in a single-center IDE approved by the FDA.

Rodney A. White, MD, is Vascular Surgery Division Chief, Vascular Surgery Fellowship Program Director, and Vice Chairman of Research, Harbor-UCLA Medical Center, and Professor of Surgery, David Geffen School of Medicine at UCLA in Torrance, California. He has disclosed that he is a paid consultant and/or receives grant/research funding from Medtronic, Inc., Abbott Vascular, Cordis Corporation, Endologix, Inc., Endomed, Inc., Nellix, Inc., Volcano Corporation, and W. L. Gore & Associates. Dr. White may be reached at rawhite@ucla.edu.

  1. White RA, Miller DC, Criado FJ, et al. Report of results of TEVAR for acute, complicated type B aortic dissection at 30 days and 1 year from IDE trials. From the Society for Vascular Surgery (SVS) Outcomes Committee. J Vasc Surg. In press.
  2. Dake MD, White RA, Diethrich EB, et al. Report on endografts management of traumatic thoracic aortic transections at 30 days and 1 year from IDE trials. A report for the Society for Vascular Surgery (SVS) Outcomes Committee. J Vasc Surgery. In press.