ObjectiveTo analyze the effectiveness of in vitro fenestration versus bypass surgery techniques in the treatment of type B aortic dissection involving the left subclavian artery by thoracic endovascular aortic repair (TEVAR).MethodsAmong the 53 patients with type B aortic dissection involving the left subclavian artery admitted to our center from January 2017 to October 2020, 23 underwent in vitro fenestration + TEVAR (a fenestration group with 18 males and 5 females aged 53.6±5.3 years), and 30 patients underwent left common carotid artery-left subclavian artery bypass + TEVAR (a bypass group with 24 males and 6 females aged 51.8±3.8 years). The effectiveness and safety between the two groups were compared.ResultsThe surgical success rate was 100.0% in both groups. And there was no death within postoperative 30 days and during the follow-up. There was no endoleak immediately postoperatively and during 1-year follow-up in the two groups. The operation time and hospitalization expenses in the fenestration group was less or shorter than those in the bypass group (P<0.05). The reduction in blood pressure of the left upper limb in the fenestration group was greater than that in the bypass group (P<0.05). There was no symptom of left upper limb ischemia, dizziness or hoarseness in both groups.ConclusionThe two methods of reconstruction of the left subclavian artery are safe and effective. In vitro fenestration can reduce surgical trauma and costs, and bypass surgery can provide better forward blood flow for the left subclavian artery.