Midterm Outcomes of the Knickerbocker Technique following Thoracic Endovascular Aortic Repair for Chronic Post-dissection Thoracic Aortic Aneurysms: A Single Centre Experience.

Abstract

The Knickerbocker (KB) technique selectively manages the thoracic false lumen (FL) following thoracic endovascular aortic repair (TEVAR). This single centre case series evaluated midterm outcomes of KB in patients with post-dissection thoracic aortic aneurysms (TAA). This study analysed a retrospective cohort including all TEVARs with the KB technique at an aortic centre between July 2014 and April 2024. Data were obtained from a prospective aortic database and electronic records. The primary outcome was technical KB success with intimal flap disruption and endograft expansion, without any KB related adverse events of aortic rupture, extension of aortic dissection, or distal stent graft induced new entry (dSINE). Secondary outcomes were positive aortic remodelling, FL thrombosis, true lumen (TL) expansion on surveillance imaging, and freedom from aortic re-intervention and aortic related death. Twenty-one patients were included (median age 63 years, interquartile range [IQR] 55, 70; 81% men), with TAA following type B (14; 67%) and repaired type A (7; 33%) aortic dissections. The majority (90%) were elective and performed during the chronic period (median time from index dissection 58 months [IQR 22, 108]). The primary outcome was achieved in all cases. There were three peri-operative adverse events (one minor stroke, one retrograde type A dissection, and one iliac rupture). Positive aortic remodelling was achieved in all patients: at 12 months, the median maximum aortic diameter reduced from 60 mm (IQR 55, 64) to 48 mm (IQR 43.5, 53.5) (p < .001), the median FL diameter reduced from 40 mm (IQR 32, 44) to 14 mm (IQR 2.5, 21.5) (p < .001), and the median TL increased from 20 mm (IQR 14, 22) to 35 mm (IQR 32.5, 36) (p < .001). Seventeen patients (81%) had FL thrombosis, with a median time to thrombosis detection of 3 months. The aortic diameter at the KB site and distally remained stable, and there was no dSINE or extension of dissection. One patient underwent aortic re-intervention at 106 months post-procedure; there were no instances of thoracic aortic re-intervention or aortic rupture (median follow up of 42 months). KB appears to be a safe and effective adjunct to TEVAR to manage post-dissection TAA.