Objective: To compare the outcomes of totally percutaneous in situ microneedle puncture for left subclavian artery (LSA) fenestration (ISMF) and chimney technique in type B aortic dissection (TBAD) during thoracic endovascular aortic repair (TEVAR).Data on patients who underwent either chimney–TEVAR (n = 89) or ISMF–TEVAR (n = 113) from October 2018 to April 2022 were analyzed retrospectively. The primary outcomes were mortality and major complications at 30 days and during follow-up.The technical success rate was 84.3% in the chimney group and 93.8% in the ISMF group (p = 0.027). The incidence of immediate endoleakage was significantly higher in the chimney than ISMF group (15.7% vs 6.2%, respectively; p = 0.027). The 1- and 3-year survival rates in the chimney and ISMF groups were 98.9% ± 1.1% vs 98.1% ± 0.9% and 86.5% ± 6.3% vs 92.6% ± 4.1%, respectively (log-rank p = 0.715). The 3-year rate of cumulative freedom from branch occlusion in the chimney and ISMF group was 95.4% ± 2.3% vs 100%, respectively (log-rank p = 0.023).Both ISMF–TEVAR and chimney–TEVAR achieved satisfactory short- and mid-term outcomes for the preservation of the LSA in patients with TBAD. ISMF–TEVAR appears to offer better clinical outcomes with higher patency and lower reintervention rates. However, ISMF–TEVAR had longer operation times with higher procedure expenses.When LSA revascularization is required during TEVAR, in situ, fenestration, and chimney techniques are all safe and effective methods; in situ, fenestration-TEVAR appears to offer better clinical outcomes, but takes longer and is more complicated.LSA revascularization during TEVAR reduces post-operative complication rates.Both in situ ISMF–TEVAR and chimney–TEVAR are safe and effective techniques for the preservation of the LSA during TEVAR.The chimney technique is associated with a higher incidence of endoleakage and branch occlusion, but ISMF–TEVAR is a more complicated and expensive technique.LSA revascularization during TEVAR reduces post-operative complication rates.Both in situ ISMF–TEVAR and chimney–TEVAR are safe and effective techniques for the preservation of the LSA during TEVAR.The chimney technique is associated with a higher incidence of endoleakage and branch occlusion, but ISMF–TEVAR is a more complicated and expensive technique.Materials and methods: To compare the outcomes of totally percutaneous in situ microneedle puncture for left subclavian artery (LSA) fenestration (ISMF) and chimney technique in type B aortic dissection (TBAD) during thoracic endovascular aortic repair (TEVAR).Data on patients who underwent either chimney–TEVAR (n = 89) or ISMF–TEVAR (n = 113) from October 2018 to April 2022 were analyzed retrospectively. The primary outcomes were mortality and major complications at 30 days and during follow-up.The technical success rate was 84.3% in the chimney group and 93.8% in the ISMF group (p = 0.027). The incidence of immediate endoleakage was significantly higher in the chimney than ISMF group (15.7% vs 6.2%, respectively; p = 0.027). The 1- and 3-year survival rates in the chimney and ISMF groups were 98.9% ± 1.1% vs 98.1% ± 0.9% and 86.5% ± 6.3% vs 92.6% ± 4.1%, respectively (log-rank p = 0.715). The 3-year rate of cumulative freedom from branch occlusion in the chimney and ISMF group was 95.4% ± 2.3% vs 100%, respectively (log-rank p = 0.023).Both ISMF–TEVAR and chimney–TEVAR achieved satisfactory short- and mid-term outcomes for the preservation of the LSA in patients with TBAD. ISMF–TEVAR appears to offer better clinical outcomes with higher patency and lower reintervention rates. However, ISMF–TEVAR had longer operation times with higher procedure expenses.When LSA revascularization is required during TEVAR, in situ, fenestration, and chimney techniques are all safe and effective methods; in situ, fenestration-TEVAR appears to offer better clinical outcomes, but takes longer and is more complicated.LSA revascularization during TEVAR reduces post-operative complication rates.Both in situ ISMF–TEVAR and chimney–TEVAR are safe and effective techniques for the preservation of the LSA during TEVAR.The chimney technique is associated with a higher incidence of endoleakage and branch occlusion, but ISMF–TEVAR is a more complicated and expensive technique.LSA revascularization during TEVAR reduces post-operative complication rates.Both in situ ISMF–TEVAR and chimney–TEVAR are safe and effective techniques for the preservation of the LSA during TEVAR.The chimney technique is associated with a higher incidence of endoleakage and branch occlusion, but ISMF–TEVAR is a more complicated and expensive technique.Results: To compare the outcomes of totally percutaneous in situ microneedle puncture for left subclavian artery (LSA) fenestration (ISMF) and chimney technique in type B aortic dissection (TBAD) during thoracic endovascular aortic repair (TEVAR).Data on patients who underwent either chimney–TEVAR (n = 89) or ISMF–TEVAR (n = 113) from October 2018 to April 2022 were analyzed retrospectively. The primary outcomes were mortality and major complications at 30 days and during follow-up.The technical success rate was 84.3% in the chimney group and 93.8% in the ISMF group (p = 0.027). The incidence of immediate endoleakage was significantly higher in the chimney than ISMF group (15.7% vs 6.2%, respectively; p = 0.027). The 1- and 3-year survival rates in the chimney and ISMF groups were 98.9% ± 1.1% vs 98.1% ± 0.9% and 86.5% ± 6.3% vs 92.6% ± 4.1%, respectively (log-rank p = 0.715). The 3-year rate of cumulative freedom from branch occlusion in the chimney and ISMF group was 95.4% ± 2.3% vs 100%, respectively (log-rank p = 0.023).Both ISMF–TEVAR and chimney–TEVAR achieved satisfactory short- and mid-term outcomes for the preservation of the LSA in patients with TBAD. ISMF–TEVAR appears to offer better clinical outcomes with higher patency and lower reintervention rates. However, ISMF–TEVAR had longer operation times with higher procedure expenses.When LSA revascularization is required during TEVAR, in situ, fenestration, and chimney techniques are all safe and effective methods; in situ, fenestration-TEVAR appears to offer better clinical outcomes, but takes longer and is more complicated.LSA revascularization during TEVAR reduces post-operative complication rates.Both in situ ISMF–TEVAR and chimney–TEVAR are safe and effective techniques for the preservation of the LSA during TEVAR.The chimney technique is associated with a higher incidence of endoleakage and branch occlusion, but ISMF–TEVAR is a more complicated and expensive technique.LSA revascularization during TEVAR reduces post-operative complication rates.Both in situ ISMF–TEVAR and chimney–TEVAR are safe and effective techniques for the preservation of the LSA during TEVAR.The chimney technique is associated with a higher incidence of endoleakage and branch occlusion, but ISMF–TEVAR is a more complicated and expensive technique.Conclusion: To compare the outcomes of totally percutaneous in situ microneedle puncture for left subclavian artery (LSA) fenestration (ISMF) and chimney technique in type B aortic dissection (TBAD) during thoracic endovascular aortic repair (TEVAR).Data on patients who underwent either chimney–TEVAR (n = 89) or ISMF–TEVAR (n = 113) from October 2018 to April 2022 were analyzed retrospectively. The primary outcomes were mortality and major complications at 30 days and during follow-up.The technical success rate was 84.3% in the chimney group and 93.8% in the ISMF group (p = 0.027). The incidence of immediate endoleakage was significantly higher in the chimney than ISMF group (15.7% vs 6.2%, respectively; p = 0.027). The 1- and 3-year survival rates in the chimney and ISMF groups were 98.9% ± 1.1% vs 98.1% ± 0.9% and 86.5% ± 6.3% vs 92.6% ± 4.1%, respectively (log-rank p = 0.715). The 3-year rate of cumulative freedom from branch occlusion in the chimney and ISMF group was 95.4% ± 2.3% vs 100%, respectively (log-rank p = 0.023).Both ISMF–TEVAR and chimney–TEVAR achieved satisfactory short- and mid-term outcomes for the preservation of the LSA in patients with TBAD. ISMF–TEVAR appears to offer better clinical outcomes with higher patency and lower reintervention rates. However, ISMF–TEVAR had longer operation times with higher procedure expenses.When LSA revascularization is required during TEVAR, in situ, fenestration, and chimney techniques are all safe and effective methods; in situ, fenestration-TEVAR appears to offer better clinical outcomes, but takes longer and is more complicated.LSA revascularization during TEVAR reduces post-operative complication rates.Both in situ ISMF–TEVAR and chimney–TEVAR are safe and effective techniques for the preservation of the LSA during TEVAR.The chimney technique is associated with a higher incidence of endoleakage and branch occlusion, but ISMF–TEVAR is a more complicated and expensive technique.LSA revascularization during TEVAR reduces post-operative complication rates.Both in situ ISMF–TEVAR and chimney–TEVAR are safe and effective techniques for the preservation of the LSA during TEVAR.The chimney technique is associated with a higher incidence of endoleakage and branch occlusion, but ISMF–TEVAR is a more complicated and expensive technique.Clinical relevance statement: To compare the outcomes of totally percutaneous in situ microneedle puncture for left subclavian artery (LSA) fenestration (ISMF) and chimney technique in type B aortic dissection (TBAD) during thoracic endovascular aortic repair (TEVAR).Data on patients who underwent either chimney–TEVAR (n = 89) or ISMF–TEVAR (n = 113) from October 2018 to April 2022 were analyzed retrospectively. The primary outcomes were mortality and major complications at 30 days and during follow-up.The technical success rate was 84.3% in the chimney group and 93.8% in the ISMF group (p = 0.027). The incidence of immediate endoleakage was significantly higher in the chimney than ISMF group (15.7% vs 6.2%, respectively; p = 0.027). The 1- and 3-year survival rates in the chimney and ISMF groups were 98.9% ± 1.1% vs 98.1% ± 0.9% and 86.5% ± 6.3% vs 92.6% ± 4.1%, respectively (log-rank p = 0.715). The 3-year rate of cumulative freedom from branch occlusion in the chimney and ISMF group was 95.4% ± 2.3% vs 100%, respectively (log-rank p = 0.023).Both ISMF–TEVAR and chimney–TEVAR achieved satisfactory short- and mid-term outcomes for the preservation of the LSA in patients with TBAD. ISMF–TEVAR appears to offer better clinical outcomes with higher patency and lower reintervention rates. However, ISMF–TEVAR had longer operation times with higher procedure expenses.When LSA revascularization is required during TEVAR, in situ, fenestration, and chimney techniques are all safe and effective methods; in situ, fenestration-TEVAR appears to offer better clinical outcomes, but takes longer and is more complicated.LSA revascularization during TEVAR reduces post-operative complication rates.Both in situ ISMF–TEVAR and chimney–TEVAR are safe and effective techniques for the preservation of the LSA during TEVAR.The chimney technique is associated with a higher incidence of endoleakage and branch occlusion, but ISMF–TEVAR is a more complicated and expensive technique.LSA revascularization during TEVAR reduces post-operative complication rates.Both in situ ISMF–TEVAR and chimney–TEVAR are safe and effective techniques for the preservation of the LSA during TEVAR.The chimney technique is associated with a higher incidence of endoleakage and branch occlusion, but ISMF–TEVAR is a more complicated and expensive technique.Key Points: To compare the outcomes of totally percutaneous in situ microneedle puncture for left subclavian artery (LSA) fenestration (ISMF) and chimney technique in type B aortic dissection (TBAD) during thoracic endovascular aortic repair (TEVAR).Data on patients who underwent either chimney–TEVAR (n = 89) or ISMF–TEVAR (n = 113) from October 2018 to April 2022 were analyzed retrospectively. The primary outcomes were mortality and major complications at 30 days and during follow-up.The technical success rate was 84.3% in the chimney group and 93.8% in the ISMF group (p = 0.027). The incidence of immediate endoleakage was significantly higher in the chimney than ISMF group (15.7% vs 6.2%, respectively; p = 0.027). The 1- and 3-year survival rates in the chimney and ISMF groups were 98.9% ± 1.1% vs 98.1% ± 0.9% and 86.5% ± 6.3% vs 92.6% ± 4.1%, respectively (log-rank p = 0.715). The 3-year rate of cumulative freedom from branch occlusion in the chimney and ISMF group was 95.4% ± 2.3% vs 100%, respectively (log-rank p = 0.023).Both ISMF–TEVAR and chimney–TEVAR achieved satisfactory short- and mid-term outcomes for the preservation of the LSA in patients with TBAD. ISMF–TEVAR appears to offer better clinical outcomes with higher patency and lower reintervention rates. However, ISMF–TEVAR had longer operation times with higher procedure expenses.When LSA revascularization is required during TEVAR, in situ, fenestration, and chimney techniques are all safe and effective methods; in situ, fenestration-TEVAR appears to offer better clinical outcomes, but takes longer and is more complicated.LSA revascularization during TEVAR reduces post-operative complication rates.Both in situ ISMF–TEVAR and chimney–TEVAR are safe and effective techniques for the preservation of the LSA during TEVAR.The chimney technique is associated with a higher incidence of endoleakage and branch occlusion, but ISMF–TEVAR is a more complicated and expensive technique.LSA revascularization during TEVAR reduces post-operative complication rates.Both in situ ISMF–TEVAR and chimney–TEVAR are safe and effective techniques for the preservation of the LSA during TEVAR.The chimney technique is associated with a higher incidence of endoleakage and branch occlusion, but ISMF–TEVAR is a more complicated and expensive technique. [ABSTRACT FROM AUTHOR]