Long-term Outcomes of Carotid-Subclavian Bypass in the Setting of Thoracic Endovascular Aortic Repair

Abstract

Subclavian artery revascularization is frequently performed in the setting of thoracic endovascular aortic repair (TEVAR) for a variety of indications ranging from prophylactic prevention of upper extremity and spinal cord ischemia to preservation of hemodialysis access or left internal mammary artery coronary artery bypass graft. Despite this, there is little information on the short- and long-term outcomes of patients undergoing carotid to subclavian artery bypass. We sought to define the outcomes associated with this procedure. Patients undergoing carotid-subclavian bypass in conjunction with TEVAR between June 2005 and September 2016 were retrospectively identified from a prospectively maintained, single-center aortic surgery database. Categorical and continuous variables were compared using χ2 and Wilcoxon rank sum tests, respectively. The 30-day outcomes specific to the carotid-subclavian bypass procedure were analyzed, including nerve injury, bleeding complications, and local vascular complications. All preoperative and postoperative chest radiographs were carefully analyzed to assess for hemidiaphragm elevation indicative of phrenic nerve palsy. Long-term outcomes included primary graft patency and anastomotic complications. Of 579 patients undergoing TEVAR during this time interval, 114 patients (20%) underwent concomitant carotid-subclavian bypass. The cohort was 39% female (n = 44), with a mean age of 65 ± 14 years. The majority of conduits were 8-mm polytetrafluoroethylene grafts (n = 107 [92.2%]), with a minority being reversed saphenous vein grafts (n = 4 [3.5%]). The bypass procedure was done concomitantly at the time of TEVAR in 90.4% (n = 103) of cases. The short-term complication rate attributed specifically to the carotid-subclavian bypass was 21% (n = 24). These complications included neck hematoma requiring re-exploration in 0.9% (n = 1), recurrent laryngeal nerve palsy in 5.3% (n = 6), axillary nerve palsy in 1.8% (n = 2), and phrenic nerve palsy in 13.2% (n = 15) of patients. The 30-day all-cause mortality rate was 5.3% (n = 6), and the rate of permanent paraparesis or paraplegia was 0.9% (n = 1). Of the operative survivors (n = 108), follow-up imaging of the bypass graft was available in 84% (n = 96) of patients. Actuarial primary graft patency was 97% at 10 years (Fig). There were three patients (2.5%) with bypass graft occlusions, two of which were clinically silent and detected in follow-up imaging. The third was detected because of the symptoms of subclavian steal and required repeated revascularization. Two patients (1.8%) developed a late anastomotic pseudoaneurysm requiring either endovascular (n = 1) or surgical (n = 1) intervention. Carotid-subclavian bypass for revascularization of the subclavian artery performed in the setting of TEVAR is durable, although the true complication rate is likely to be higher than generally reported in the literature because of a not insignificant rate of phrenic nerve palsy. These data should serve well as “gold standard” comparison data for emerging branch graft devices.