Data from a clinical trial assessing the safety and efficacy of the Castor Branched Aortic Stent-Graft System for the treatment of thoracic dissection has been released by MicroPort, the device’s manufacturer.
Thoracic aortic dissections often involve or lie in close proximity to the left subclavian artery. In order to seek relatively healthy and sufficient landing zone, the left subclavian artery ostium is often covered during TEVAR with or without concomitant subclavian artery revascularisation. However, subclavian occlusion can cause hand and upper limb ischaemia, subclavian steal syndrome, and spinal cord ischaemia. Although it is possible to preserve the left subclavian artery through hybrid technique, chimney technique, or fenestration, all these methods have inherent deficiencies especially endoleak, chiminey graft occlusion, device kink, etc. Therefore, an easy-to-use unibody branched stent graft has become key to solve these clinical issues, the company says.
According to MicroPort, Castor is designed for an entirely endovascular treatment of thoracic dissection encroaching the left subclavian artery or the original tear located within 15mm distal to the left subclavian artery. Castor employs an easy-to-use unibody design, including a main body and a left subclavian branch graft to avoid type III endoleaks. Zhonghua Li, vice president of MicroPort Endovascular, said: “The key design of Castor is how to safely and accurately place the branch stent in the target artery, which is ensured by a unique two-layer out-sheath design and wire release mechanism. Adjustment of the direction of the stent graft can be performed accurately and safely under the protection of two middle soft sheaths for main body and branched stent grafts. A full deployment of the stent graft is conducted through a safe wire release mechanism.
Six-month data of the CASTOR trial from 73 patients demonstrate safety and efficacy of the branched aortic stent graft system for the treatment of thoracic dissections. Conducted at 11 centres in China, the trial met its primary efficacy endpoint by achieving 98.6% technical success with two occlusions of the left subclavian artery for operational reasons. No further branch artery occlusions were observed during six-month follow-up. The six-month stroke rate is 2/70, which was not device related. There are two device-related severe adverse events, including one endoleaks and one reintervention due to distal development of the dissection. The dissection-related mortality rate was 2/73, and the all-cause mortality was 4/73.
Zaiping Jing, chief of Vascular Surgery Department of the 2nd Military Medical University-Changhai Hospital, served as the national principal investigator for the CASTOR trial, and Qingsheng Lu, from the same hospital, worked as a major operator for CASTOR trial. They said: “The Castor system is the leading product around the world which allows physicians to safely treat aortic aneurysms or dissections near the aortic arch while maintaining blood flow to all branch vessels using an entirely endovascular approach.”