Covering/Overstenting of the left subclavian artery (LSA) in thoracic endovascular repair (TEVAR) to treat various thoracic/thoracoabdominal aortic lesions: is revascularization of the left arm a must?(A retrospective cohort study with 12 years of experience to describe the real-world situation of daily clinical practice and the literature review)
Authors: Ghanem Mohammad , Meyer Frank , Tautenhahn Joerg , Udelnow Andrej , Halloul Zuhir 
Published: April 2022

<b> Introduction:</b> Pathologies of the descending thoracic aorta inwardly extended towards the aortic arch actually shorten the proximal landing zone for aortic prosthesis. This, in turn, worsens the accessibility of the aorta for endovascular therapeutic options of those pathologies. </br></br> <b> Aim:</b> This work considers the blockage of the left subclavian artery (LSA) through endovascular treatment of the pathologies of the descending aorta as the main work question, based on the hypothesis that there is no necessity for primary standard revascularization of the LSA in TEVAR with LSA covering. The researchers have 12 years of experience in the treatment of different thoracic aortic lesions. Their experience will also be reviewed in this paper. </br></br> <b> Materials and methods:</b> Retrospective unicenter cohort study in consecutive patients to describe the real-world situation of daily clinical practice. All patients who had undergone endovascular, hybrid, or open operative therapy of different pathologies of the descending aorta were included in this study. Various parameters were investigated, including therapeutic procedures such as 1) pure endovascular vs. hybrid; 2) year of therapy; 3) symptomatic vs. asymptomatic status of the patients; 4) different epidemiological factors (age, sex, risk factors, mortality, and follow-up); 5) overstenting/blocking of the LSA; 6) complications of applied therapies; 7) further operations/interventions to treat such complications; 8) radiological aortic measurements (such as lumen extensions, false lumen measurements, distance to the supra-aortic and visceral vessels); and 9) multiple other pathological features. Different statistical parameters were also examined. Survival was analysed with the Kaplan-Meier assessment in the group of whole patients vs. the group of over-stented patients. The analysis of variance was performed for independent parameters for the revascularized patients – not the revascularized patients – who had undergone LSA coverage. For statistical approval, the U-test was used. The P-value < 0.05 was considered significantly different. The literature review was performed by means of a search in PubMed, Google scholar, Research Gate, ScienceDirect, and Cochrane library, using the following terms: endovascular, TEVAR, revascularization, stroke, and left-subclavian-artery ischemia. The literature is classified accordingly in relation to the main topic. In fact, the literature underwent further analysis depending on the fact whether it went with or against our hypothesis. </br></br> <b> Results:</b> Overall, 112 patients were enrolled in the study. There was no significant difference comparing the non-revascularized vs.the revascularized group of patients, considering the consequences on cerebrovascular circulation (hemorrhagic, n = 1 case [4.8%] vs. 0 case [0%]; p = 0.32 and ischemic, n = 2 cases [9.6%] vs. 1 case [4.8%]; p = 0.56). There was no registered cases of spinal cord ischemia or left arm ischemia. As the main result, there was no case of left arm ischemia or death (mortality, 0). Survival was as follows for both groups: 22 [95% CI, 14.154–29.904] months vs. 43 [95% CI, 33.655–51.921] months, respectively, with no significant statistical difference (P > 0.05). The only statistically significant risk factor found was renal insufficiency (P, 0.028) but this too was considered a trend by the urgency of revascularization. Postoperatively, pneumonia showed a trend of higher frequency (P = 0.058) in the revascularized cases (n = 0 in the non-revascularized vs. n = 3 [21.4%] in the revascularized cases). There was no significant difference in the occurance of postoperative neurovascular complications (such as cerebrovascular accidents, spinal cord ischemia, or left arm ischemia) by comparing the groups of non-revascularized and revascularized patients. </br></br> <b> Conclusions: </b> The revascularization of the overstented LSA due to TEVAR should be limited to certain indications, including 1) inadequate intracerebral circle of Willis; 2) predominantly perfused left vertebral artery with inadequate blood perfusion via the right vertebral artery (e.g., by stenosis), 3) anatomic variance such as the left vertebral artery originating directly from the aortic arch (and must be blocked by TEVAR); 4) need of an adequate left internal thoracic artery for coronary artery bypass grafting (CABG); 5) need of a patent LSA for the dialysis shunt of the left arm. However, there is no appropriate evidence as yet based on sufficient study results achieved in trials with an advanced design (such as [double-]blind, multicenter randomized study) that appears to be urgently required.