Patients
Patients who had aortic arch aneurysm arising distal to left carotid artery (distal arch aneurysm) and underwent d-TEVAR or TAR for degenerative aortic arch aneurysm between 2008 and 2015 at our hospital and aged ≥75 years were included in this study. Patients were indicated for surgery if exhibited a thoracic aortic aneurysm of ≥60 mm. In principle, debranching TEVAR for aortic arch aneurysm without sternotomy was performed, if feasible, after introducing d-TEVAR in 2010, whereas TAR was performed in patients with aneurysms extending to near the brachiocephalic artery so that sufficient proximal landing zone was not assured. Patients who received endovascular treatment with sternotomy or with chimney technique were not included. A closed-chest technique was adopted for all debranching TEVAR, and bypass to the cervical branch or simple closing of the left subclavian artery was simultaneously performed. TAR was performed for patients in whom closed-chest debranching TEVAR is anatomically difficult to perform.
Patients who received endovascular aortic repair with cervical debranching technique or simple closing of the left subclavian artery when treating aortic arch aneurysm were included in the debranching TEVAR group (d-TEVAR), and patients who received TAR were included in the TAR group.
This study was carried out in accordance with principles outlined in the Declaration of Helsinki. It was conducted after obtaining approval from the ethics committee of Tottori University Faculty of Medicine.
Procedures of endovascular treatment
Treatment strategy was determined according to Zone classification, in principle. The proximal side of the endograft should be able to be fixed in zone 1 or 2 in patients in the d-TEVAR group. At least 2 cm of the landing zone to the proximal side was ensured. For graft landing in zone 1, the left common carotid artery (LCCA) and the left axillary artery (LAA) were bypassed from the right axillary artery (RAA). As a basic policy, the LCCA was tied at the proximal to the anastomosis of the bypass and the origin of the left subclavian artery was coiled after bypass (Fig. 1a). For graft landing in zone 2, LCCA-LAA bypass, or RAA-LAA crossover bypass was performed. The origin of the left subclavian artery was also coiled after bypass in this case as a basic policy (Fig. 1b).
Procedures of total arch replacement
A median sternotomy approach was employed for all patients. Cardiopulmonary bypass was established with venous drainage from the superior and inferior vena cava and the blood return to the right axillary artery and the either side of the femoral artery. Core body temperature was cooled to ≤25 °C and total arch replacement was performed with quadrifurcated graft under selective cerebral perfusion and open distal technique.
Postoperative follow-up and data analysis
Patients were periodically followed-up as outpatients following surgery, and contrast enhanced or plain computed tomography was performed once a year during the follow-up period. If patients failed to visit hospital, survival was confirmed via telephone.
Permanent neurological deficits (PND) were defined as the presence of deficits at the time of hospital discharge. Transient neurological deficits (TND) were defined as the deficits that recovered by hospital discharge.
As endpoints, 30-day death, hospital death, duration in ICU, incidence of PND, spinal cord disorder, duration in hospital, transfer to a rehabilitation hospital, time until home discharge, requirement for postoperative tubal feeding, cumulative survival rate, and aorta-related event-free rate were evaluated.
Statistical analysis
All numerical data are shown as averages ± standard deviation (SD). All data were analyzed using PASW Statistics ver. 24 (IBM SPSS Inc., Chicago, USA). The unpaired t test was used for comparisons of continuous variables. We utilized Kaplan-Meier curves and the log-rank test to compare the endpoints. Differences with a P value < 0.05 were considered statistically significant.
Owing to the non-randomized nature of the study, and considering for significant differences in baseline characteristics, propensity-score matching was used to control for potential confounders of the treatment outcome relationship. Propensity scores were calculated using logistic regression with surgical procedure as the dependent variable. The propensity score included 10 variables, including age, sex, hypertension, chronic obstructive pulmonary disease (FEV1.0% < 70%) (COPD), diabetes (treatment with insulin or oral hypoglycemic agents), history of coronary disease (history of percutaneous coronary intervention or coronary bypass), hemodialysis, previous sternotomy, history of cerebrovascular disease, and preoperative creatinine level. For each patient of debraching TEVAR group, a propensity score-matched patient of TAR group was selected (1:1) using the one-to-one nearest neighbor method and no replacement.