Will the open revascularization of the left subclavian artery for proximal landing zone extension in thoracic endovascular aortic repair become obsolete?

For pathologies of the descending aorta, thoracic endovascular aortic repair (TEVAR) has become the first-line therapy. For long-term success, adequate proximal and distal landing zones are mandatory. In a retrospective study, it was shown that at least a length of 25–30 mm is necessary for the proximal landing zone for type II and III arches [1]. Since 40% of aortic pathologies extend to the left subclavian artery (LSA), revascularization of the LSA is often required to generate an adequate proximal landing zone [2]. LSA coverage without revascularization in the context of TEVAR implantation leads to a significantly increased 30-day risk of stroke and left arm ischaemia [3]. There are different open surgical and endovascular methods for revascularization of the LSA, which is also recommended by guidelines before TEVAR [4]. While open debranching uses carotid-subclavian bypasses or transpositions of the LSA, endovascular debranching has been performed using parallel graft techniques or physician-modified stent grafts. In a comparative study (open revascularization versus parallel graft technique), Dueppers et al. demonstrated that both techniques can achieve comparable reintervention and mortality rates. However, open debranching showed significantly higher rates of technical and clinical success and fewer type I endoleaks. This led to the recommendation that the open procedure should be preferred whenever possible [5]. But it should not be ignored that the open debranching procedure can also be associated with stroke rates of 2–9% and phrenic nerve injuries as high as 25% [6]. To overcome these shortcomings of available methods for endovascular and open debranching, some companies are working on off-the-shelf branched endografts that have their proximal landing zone in Ishimura zone 2 and keep the LSA patent. None of these stent grafts have been available in Europe until recently. The Castor single branched stent graft (Microport Medical, Shanghai, China) has become the first commercially available stent graft of this type in some countries in Europe. However, it has been available in China for several years and initial results for various pathologies have already been published. In a prospective multicentre trial published in 2020, the long-term outcomes (median follow-up 61 months) of 73 patients with Stanford type B aortic dissection treated with a Castor stent graft were presented. The majority of patients were acute dissections treated within 2 weeks of the initial event (n = 50; 68%). One death occurred during the inpatient stay without further major complications. The intraoperative endoleak rate (2× endoleak type Ia, 2× endoleak type Ic) and the 1-year mortality rate were both 5.5%. Interestingly, no stroke occurred. This was certainly favourably influenced by the low mean age of 56.8 years and the low amount of atheromatous changes in the aortic arch in dissections [7]. In the present study by Huang et al. [8], in this issue, the patient population (n = 25) was significantly older (mean age 71.0 years) and due to the underlying pathology [penetrating aortic ulcer (PAU)] likely with a higher atheromatous burden in the aortic arch. Perioperatively, there were no deaths or nerve lesions and only 1 stroke (4.0%). One patient had an endoleak type Ia. During follow-up (mean 14.0 months), 2 branch occlusions occurred. Even though in this study 2 different aortic pathologies with PAU and ulcer-like projections were mixed and the number of cases is very small, the results are similar promising to the publication of Jing et al. [7]. Although further studies are certainly needed, it is already obvious that branched TEVAR may be a safe alternative for debranching of the LSA in aortic pathologies and may even represent the first-line therapy in the future as it can address the shortcomings of open and currently available endovascular therapy. Or to put it in the words of Humphrey Bogart: ‘I think this is the beginning of a beautiful friendship’ [9]. Conflict of interest: Alexander Zimmermann is a proctor for Cryolife/Jotec and for Cook Medical. He received honoraria from Lombard Medical/2PlusMedical and is a member of an Advisory Board for Medtronic. Benedikt Reutersberg is a proctor for Terumo Aortic.