Transcatheter aortic valve implantation (TAVI) has become the standard procedure for the management of severe aortic stenosis in high-risk or inoperable patients.1 Recently, its use has also proved safe and effective in intermediate-2,3 and low-surgical risk4–7 elderly patients.

However, several significant periprocedural complications need to be taken into consideration, such as the occurrence of new conduction disturbances requiring permanent pacemaker implantation (PPMI), which remains frequent.8 Despite greater operator experience and technical advances in percutaneous aortic valve engineering and design, there has been little or no improvement over the years in PPMI incidence, which ranges from 3.4% to 25.9% in different series.6,9 PPMI has been associated with longer hospital stay, increased costs (accounting for 25% of TAVI procedure expenses)10 and worse long-term prognosis.11–15

Several factors have been associated with an increased risk of post-TAVI conduction disturbances,6 the most robust independent predictors being pre-existing right bundle branch block (RBBB), the use of self-expanding valves, balloon post-dilation and a lower (i.e. more ventricular) valve implantation depth (ID).6,16–19 Lower ID is associated with a greater probability of the prosthetic valve interfering with the conduction system and consequent conduction disturbances. Accordingly, it is of utmost importance to adopt an angiographic projection that can ensure the most precise positioning of the valve.

In recent years, the cusp-overlap projection (COP) implantation technique, which uses a view overlapping the right (RCC) and left (LCC) coronary cusps that isolates the noncoronary cusp (NCC), has been advocated as a preferable projection for deployment of self-expanding valves compared to the conventional three-cusp coplanar implantation technique (CIT), which aligns the RCC between the LCC and the NCC.

The advantage of the COP technique stems from the acquisition of a better nadir of the NCC, which contributes to a higher and more precise valve position to start deployment, minimizes the risk of valve embolization and enables improved orientation of the delivery system in relation to the center of the aortic annulus.20–22 These advantages have led to widespread adoption of the COP technique; however, robust evidence regarding the real impact on PPMI of its use after self-expanding valve implantation is still lacking, since no randomized controlled trials are available.

We aimed to compare the 30-day incidence of post-TAVI PPMI using a self-expanding valve (CoreValve™) according to the fluoroscopic guidance technique (COP vs. CIT).

An observational, longitudinal, retrospective, single-center study was carried out. Demographic and clinical characteristics, in-hospital therapeutic measures and follow-up data were obtained by consulting the electronic medical record system (SClinic®, Alert®, syngo Dynamics®).

We included all consecutive patients undergoing TAVI in the context of severe native aortic valve disease with self-expanding new generation CoreValve Evolut R™ or Evolut PRO™, at a high-volume tertiary center, between April 18, 2019 and November 22, 2021. The procedure was performed using CIT until 19 January 2021 and COP thereafter.

Patients with a previously implanted pacemaker, cardiac resynchronization therapy device or implantable cardioverter-defibrillator, bicuspid aortic valve, or who underwent valve-in-valve procedures were excluded.

Transcatheter aortic valve implantation procedure

Before valve implantation, electrocardiogram (ECG)-gated contrast-enhanced high-resolution computed tomography (CT) images were acquired in all patients following standard recommendations.23 Images were analyzed using dedicated software (3Mensio Structural Heart, Pie Medical Imaging BV, The Netherlands) to determine anatomic dimensions and working projections. This information was then used to select the valve size and vascular approach, and to predict the angiographic projection angulations for deployment of the device throughout the procedure. Deployment was confirmed and corrected with fluoroscopic guidance.

COP was defined on CT as an overlap of the LCC and RCC, isolating the NCC; CIT was defined as the projection aligning the three coronary cusps in the same plane.

After advancing the valve through the delivery catheter, partial release was performed once the valve's height was considered optimal according to the operator, typically at the annulus level. Flaring of the valve occurred using the NCC as the first contact point followed by the LCC. This occurred under rapid pacing achieved by the delivery wire positioned inside the left ventricle. The valve was repositioned according to the operators’ discretion to obtain an implantation depth between 3 and 5 mm below the annulus. Definitive delivery occurred if the valve hemodynamics was deemed appropriate. Balloon pre- and/or post-dilation was performed at the operators’ discretion but usually in the presence of a heavily calcified native valve.

ID, defined as the distance from the aortic annulus to the distal end of the prosthetic valve, was measured retrospectively in patients in whom a final image was obtained with a projection in a perpendicular plane to the valve with a contrast bolus injection. Measurements were made using syngo Dynamics (Siemens Healthcare, USA). There is no standardized method for measuring ID, and at least three different approaches (Figure 1) have been described in previous studies24,25: (1) the distance from the NCC to the prosthetic valve; (2) the arithmetic mean of the distance from the NCC and the LCC to the valve; and (3) the deepest edge from the NCC or the LCC to the valve. Taking this into consideration we measured ID with the three methods described.

Figure 1.

Depth assessment measured from the noncoronary cusp (yellow dot) and the left coronary cusp (blue dot), respectively, to the deepest intraventricular portion of the valve.

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We found that, compared to the standard angiographic approach, the COP implantation technique (Figure 3) did not reduce the development of conduction disturbances or the 30-day PPMI rate. It was also safe, without increased risk of other complications, and was feasible without adding complexity to the procedure.

Figure 3.

Central figure of the main results of the study. AVB: atrioventricular block; CIT: coplanar implantation technique; COP: cusp-overlap projection; PPMI: permanent pacemaker implantation; TAVI: transcatheter aortic valve replacement.

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As a greater ID is associated with a higher probability of post-TAVI PPMI,27–29 a new angiographic method such as COP that enables higher valve deployment would represent a significant advantage. This would be even more valuable considering that ID is one of the few modifiable predictors of post-TAVI conduction disturbances.

In a literature review, we found only four retrospective observational studies addressing the effect of this fluoroscopic technique on post-TAVI conduction disturbances that found a significant reduction of PPMI with the use of COP.30–33 Among these, only two also analyzed the impact of the COP technique on ID (using the same three different methods as in our study), with inconsistent results. One study32 showed a significant reduction in ID compared to the standard fluoroscopic approach only when using NCC distance, while another33 found a significantly higher ID in the COP group when applying NCC or arithmetic mean ID measures. These discrepancies raise questions about the ability of the COP technique to enable higher valve deployment. Additionally, it should be noted that we found no studies on this topic with the same conclusion as ours, which could raise the possibility of bias in preferential publication of positive results.

We found no significant difference between the CIT and COP groups regarding 30-day PPMI incidence. The failure to achieve a significant reduction in ID in the COP group could have significantly influenced this result. It should also be pointed out that, in our study, ID was somewhat lower in both groups compared to the defined target (3–5 mm) and the mean ID achieved in other studies,33 which could also have had a significant impact on our results. Although first operator experience was not associated with significant differences regarding the PPMI rate and ID, the influence of the technique's learning curve on the failure to reduce ID with the COP technique cannot be excluded.

The management of conduction disturbances in the context of TAVI was revised in the 2021 European Society of Cardiology guidelines on cardiac pacing and cardiac resynchronization therapy.34 Until then, recommendations were limited to expert consensus.8

Like ours, previous studies on this subject analyzed two consecutive cohorts of patients. However, these were performed at an earlier time and patient recruitment was longer. Since the evidence regarding post-TAVI conduction disturbances that would benefit from pacemaker implantation was limited in the past, there was a lower threshold for device implantation even with minor conduction disturbances. This could have resulted in a higher PPMI rate in the first years of these studies (during which the CIT technique was applied) and an improvement in terms of 30-day PPMI post-TAVI in the COP group (which was recruited later) that was not attributable to the technique. This tendency was observed in our study, although it did not reach statistical significance, with no high-degree AVB or alternating BBB underlying pacemaker implantation decisions in 12.5% of the COP group vs. 27.8% of the CIT group (p=0.41). None of the above-mentioned observational studies identified the underlying causes for device implantation, which makes it impossible to confirm this potential bias.

Several independent predictors of conduction disturbances and PPMI after TAVI have been described: patient-related (advanced age, male gender and higher body mass index); anatomic (mitral annular, aorta and/or left ventricular outflow tract [LVOT] calcifications; short membranous septum); electrocardiographic (previous RBBB, left anterior hemiblock and first-degree AVB); and procedural factors (self-expanding valve, lower ID, larger valve/LVOT diameter ratio, balloon post-dilation).34 With the exception of membranous septum length, which was not measured, all non-ID variables had a similar distribution between the two groups in our study. Accordingly, it is unlikely that these could have influenced our results regarding PPMI incidence. Nevertheless, special note should be taken of the fact that, although there was no statistically significant difference between the two study groups in the incidence of pre-existing RBBB (which is the most consistent and powerful predictor for post-TAVI conduction disturbances), the number of patients with pre-existing RBBB was slightly higher in the COP group. In a relatively small sample like ours this could have had some effect on the final result, leading to overestimation of the need for a pacemaker in patients undergoing TAVI using COP fluoroscopic guidance (the incidence of PPMI was 47.1% in patients with pre-existing RBBB compared to 22.9% in those without, p=0.04).

While a higher valve deployment may confer protection against conduction disturbances, it can also increase the risk of valve embolization, paravalvular leak and coronary occlusion (especially when ID is less than 3 mm).35 However, in our sample there was only one case of valve embolization in the CIT group (1.6%) and none in the COP group (p=1.00). This is consistent with other observational studies that reported few cases of valve embolization, with more cases reported in the CIT groups.32,33 There were no cases of acute coronary occlusion and no significant difference between the two groups in the percentage of grade III or IV post-TAVI aortic regurgitation.

The distribution of other VARC-2 safety criteria was also comparable between the two groups, which confirms the safety of the COP technique.

As in previous studies,20 implementation of the COP technique did not add complexity to the standardized TAVI protocol, as shown by similar fluoroscopy time and iodinated contrast volume used in the two groups; and lower radiation dose used in the COP group.

The main limitations of our study are related to its small sample size and retrospective observational design. Although consecutive series of patients were compared, selection bias cannot be excluded. We analyzed only one type of self-expanding valve implanted in a high-volume center; therefore, the results may not be generalizable to other settings.

The decision to implant a pacemaker was ultimately at the discretion of the local heart team; however, since this is a single-center study over a short period, the adoption of different thresholds for PPMI in the two groups is unlikely.

Our study suggests that the COP technique is a safe and simple modification of the conventional three-cusp view for self-expanding valve implantation during the TAVI procedure. However, in contrast to previous studies, it did not decrease the incidence of high-degree AVB or of the 30-day PPMI rate. Dedicated larger randomized trials are needed to assess the impact of this strategy.

None declared.

The authors have no conflicts of interest to declare.