Aortic Root Anatomy and Impact on New-Onset Left Bundle Branch Block After Transcatheter Aortic Valve Implantation.

Background: Angulation of virtual basal ring (VBR), also known as aortic annulus, in relation to sino-tubular junction (STJ) may lead to greater exposure of implanted stent to the conduction system, consequently increasing the risk of left bundle branch block (LBBB).

Aims: We sough to measure the VBR-STJ angle and explore its impact on the development of LBBB post-TAVR.

Methods: Patients undergoing TAVR using the Sapiens 3 valve between 2016 and 2021, without pre-TAVR conduction anomalies were included. The angle between the VBR and the ascending aorta was measured as the angle between the VBR plane and the plane of the STJ on cardiac CT, along with the annulus dimensions. TAVR implantation depth was measured on fluoroscopy images.

Results: A total of 1204 patients were included, with 145 having new-onset LBBB. The VBR-STJ angle was significantly greater in the new-onset LBBB group (7.3 ± 4.7 vs. 5.9 ± 4.6, p = 0.002), and the difference in implantation depth between the levels of right and none coronary cusp (RCC and NCC) was significantly correlated with the VBR-STJ angle (r = 0.3, p = 0.03). This angle was further associated with new-onset LBBB after adjustment to patient and procedural characteristics (OR 1.08 CI: [1.04, 1.13], p < 0.001).

Conclusion: Patients developing LBBB have larger VBR-STJ angle which was associated with greater depth of implantation of the TAVR valve below the RCC compared to the NCC. Precise understanding of the aortic root anatomy can help to predict onset of LBBB which in turn can inform decision-making regarding optimal way of treating aortic stenosis and may improve procedure planning.