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)

Background: 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 feasibility of the aorta for endovascular therapeutic options of those pathologies. Objective: This work considers the blockage of the left subclavian artery (LSA) through endovascular treatment of the pathologies of the descending aorta as a main work question, which is 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 treatment of different thoracic aortic lesions. Their experience will also be reviewed in this paper. Design: Retrospective unicenter cohort study in consecutive patients order to describe the real-world situation of daily clinical practice Material: All the patients who had undergone endovascular, hybrid, or open operative therapy of variant pathologies of descending aorta were included in this study. Methods: Various parameters were investigated, including therapeutic procedures such as i) pure endovascular vs. hybrid; ii) year of therapy; iii) symptomatic vs. asymptomatic status of the patients; iv) variant epidemiological factors (age, sex, risk factors, mortality, and follow up); v) overstenting/blocking of the LSA; vi) complications of applied therapies; vii) further operations/interventions to treat such complications; viii) radiologic aortic measurements (such as lumen extensions, false lumen measurements, distance to the supra-aortic and visceral vessels); and ix) multiple other pathological features. Different statistical parameters were also examined. Survival was analysed by the Kaplan–Meier assessment in the group of whole patients vs. the group of over-stented patients. Here the analysis of variance is performed for the independent parameters for the revascularized patients—not the revascularized patients—who had undergone LSA coverage. For statistical approval, U-test was used. The p-value < 0.05 was considered significantly different. The literature review was achieved by a search in PubMed, Google scholar, Research Gate, ScienceDirect, and Cochrane library by 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 undergoes further analysis if it goes with or against our hypothesis. Results: Overall, 112 patients were enrolled in the study. There was no significant difference comparing the not-revascularized vs. the revascularized group of patients, considering the consequences on cerebrovascular blood circulation (in particular, n=1 case [4.8 %] vs. no case [0 %]; p=1) or the spinal cord ischemia (n=2 [9.5 %] vs. n=1 [7.1 %]; p=1). As the main result, there was no case of manifest left arm ischemia and deaths (mortality, 0). Survival was in both groups as follows: 22 [95% CI, 14.154–29.904] months vs. 43 [95% CI, 33.655–51.921] months with no significant statistical difference (p>0.05) . The only statistically significant risk factor found was renal insufficiency (p, 0.028), but this too is 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 not-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 not-revascularized and revascularized patients. Conclusion: The revascularization of the overstented LSA due to TEVAR should be limited to certain indications, including i) the inadequate intracerebral circle of Willis; ii) the predominantly perfused left vertebral artery with inadequate blood perfusion via the right vertebral artery (e.g., by stenosis), iii) anatomic variance such as the left vertebral artery originating directly from the aortic arch (and must be blocked by TEVAR); iv) the need of an adequate left internal thoracic artery for coronary-artery-bypass grafting (CABG); v) the need of 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.