**5.3 Pacemaker implantation**

High-grade atrioventricular block requiring permanent pacemaker implantation (PPI) is one of the most common complications following TAVI, with an incidence ranging from 2 to 36%, depending on the patient population in exam and the prosthesis design [74]. Notably, the rate of PPI remains high even in recent trials with newer generation devices compared with previous trials [74, 75]. SEV is associated with higher risk of PPI than BEV, probably because of the increased radial force exerted on the left ventricle outflow tract (**Figure 7**). In the Core Valve High-Risk trial, PPI was significantly more frequent in the TAVI group than in the SAVR group (19.8% vs. 7.1%, p < 0.001) [65]. A more frequent occurrence of PPI in TAVI patients was also observed in the Evolut Low-Risk trial [10]. In the PARTNER III trial, the rate of PPIassociated TAVI was similar to that of surgical patients (6.6% vs. 4.1%, hazard ratio 1.65; 95% CI, 0.92 to 2.95), although the onset of a new left bundle block was more common after TAVI (22.0% vs. 8.0%; hazard ratio 3.17; 95% CI 2.13 to 4.72) [8].

The link between the occurrence of conduction disturbances and the TAVI procedure is explained by the proximity between the aortic valve and the structures of the cardiac conduction system. The atrioventricular node is situated in the right atrium, continues as the Bundle of His, and then splits into the left and the right bundle branches. The Bundle of His emerges at the level of the interventricular membranous septum, caudally to the commissure between the right and noncoronary cusp. The course of the Bundle of His may be within the right half of the membranous sept,

#### *Transcatheter Treatment of Aortic Valve Disease Clinical and Technical Aspects DOI: http://dx.doi.org/10.5772/intechopen.105860*

within the left half, or under the endocardium; conduction disorders during TAVI are lower with the first anatomic variant [76, 77]. During TAVI, the conduction system can be injured by the insertion of guidewires, balloon pre-dilation, and valve deployment.

The conduction disturbances after TAVI range from new-onset complete atrioventricular blockade to left bundle branch block and transient complete atrioventricular block. The presence of baseline right bundle branch block (RBBB) is the strongest predictor of need for PPI. Other predictors for PPI after TAVI are PR-interval prolongation, left anterior hemiblock, older age, presence of left ventricle outflow tract calcifications, severe mitral annular calcification, and the length of the membranous septum. Procedural predictors are the use of SEV, deeper valve implantation, balloon pre- and post-dilation, and prosthesis oversizing (**Figure 8**) [74, 78–80].

As per standard of care, PPI is recommended when the patient develops a persistent complete or high-grade atrioventricular block after TAVI. It is also recommended in case of new-onset alternating bundle branch block, while it may be considered in

**Figure 7.** *Relationship between transcatheter heart valve and conduction system.*

**Figure 8.** *Major factors associated with permanent pacemaker implantation after TAVI.*

patients with pre-existing right bundle branch block who develop new post-procedure conduction disturbance. There is not yet consensus about the optimal strategy for patients with other conduction abnormalities [78].

PPI after TAVI has been associated with increased mortality and rehospitalization, as the need for RV pacing may lead to decreased LV function and heart failure, yet there is still conflicting evidence [78, 81]. Risk factors that should be assessed in the preoperative TAVI evaluation are preexisting conduction disturbances and LVOT calcification. There may be a trade-off between the reduction of PVL and the risk of PPI, as a greater radial force may reduce the regurgitation, but it may damage the conduction system [52]. A BEV may be preferred in patients with baseline conduction disorders. A higher implantation strategy may minimize the contact between the valve and membranous septum, reducing conduction defects after the implantation [82]. In this context, an angiographic view providing an accurate visualization of the implantation depth (the cusp overlap view, as the right coronary cusp and the noncoronary cusp appear overlapping) demonstrates to reduce the rate of PPI [83].
