The timing and mechanism of high-grade AV block post-TAVI: knowing your enemy

Abstract Background Complete atrioventricular block (AVB) requiring permanent pacemaker implantation (PPMI) is still a major limitation of transcatheter aortic valve implantation (TAVI) procedures. Although right-bundle branch block (RBBB), membranous septum (MS) length and self-expandable prothesis are recognizable risk factors, their predictability to PPMI is far from satisfactory. While some patients develop persistent intra-procedure high-grade AVB (H-AVB), others present much later with severe bradycardia. Purpose This study aims to describe and compare the characteristics of patients who develop AVB during or after TAVI. Methods Single centre prospective registry of 506 consecutive patients submitted to TAVI with no previous pacemaker between 2017 and 2020. Post-procedure PPMI (up to 30 days after discharge) was studied and divided into two groups according to the development of persistent intra-procedure H-AVB (Group A) or post procedure H-AVB (Group B). Baseline ECG, computed tomography and TAVI-related characteristics were analyzed. Results A total of 88 patients (17,3%), aging 83±6 years, 36.4% male, underwent post-TAVI PPMI (6 after discharge). Previous conduction disturbances were present in 50 (56.8%) patients and 25 (28.4%) had RBBB. 83% were submitted to self-expandable TAVI. Forty-two patients (47.7%) had persistent intra-procedure H-AVB (Group A) whereas 52.3% had post-procedure H-AVB (Group B). In patients with persistent intra procedure H-AVB previous RBBB was significantly more frequent (45.2%, n=19) when compared to patients with post-procedure H-AVB (13%, n=6; p=0.001). Contrarily, AF and previous left-bundle branch block (LBBB) were more likely in Group B. No difference in valvular calcification, MS length, prosthesis type or implantation technique was noted (picture 1). In the group with post-procedure H-AVB, 21.7% had transient AVB during TAVI and all developed de novo LBBB or first-degree AVB post-TAVI. Among these, 33 patients (71.7%) developed delayed H-AVB (>48h post-procedure) while the remaining presented earlier. Conclusions In patients with PPMI post-TAVI, those with persistent intra-procedure H-AVB had higher rates of previous RBBB, while those with post-procedure H-AVB frequently had a normal baseline ECG. Anatomical and procedural characteristics did not differ between groups. Further studies are needed to confirm these results. Funding Acknowledgement Type of funding sources: None.