Background

Transcatheter aortic valve replacement (TAVR) can lead to changes in the conduction system due to increased forces on the atrioventricular node and His bundle, leading to potential complications such as complete heart block necessitating PPM implantation. Multiple studies have demonstrated worsening long-term outcomes in patients receiving PPM after TAVR.¹ Expanding indications of TAVR (now including low-risk patients with aortic stenosis) require operators to be more critical in reducing rates and risks of potential conduction disturbances and PPM post-TAVR. With improved operator technique and experience, several methods have been developed to decrease the risk of potential PPM implantation. Here, we evaluate two studies to assess how these techniques can affect rates of PPM implantation post-TAVR.

Low Rates of Permanent Pacing Are Observed Following Self-Expanding Transcatheter Aortic Valve Replacement Using an Annular Plane Projection for Deployment²

Key Questions

• To evaluate whether balloon-expandable TAVR implantation in co-planar view (3-cusp view) and self-expandable TAVR implantation in RAO/CAU cusp-overlap view had differential outcomes in terms of PPM implantation at a single center.
• Previous studies have demonstrated rates of PPM implantation up to 17% for self-expandable valves such as the Medtronic CoreValve (Medtronic; Minneapolis, MN) with recommendations for valve implantation between 3 and 5 mm as measured below the aortic valve annulus usually deployed in a left anterior oblique (LAO) projection after correction of parallax in the device.

New Technique (Cusp Overlap)

• All patients underwent TAVR in a co-planar projection that was predicted using computed tomography for deployment of the valve. For self-expanding Medtronic CoreValve, correction of the parallax was performed in an RAO-CAU projection, essentially producing cusp-overlap view, overlapping right and left cusp and isolating the non-coronary cusp.

Characteristics

• A total of 527 patients was included in a retrospective analysis of patients undergoing TAVR from January 2013 to August 2019 within a single center. The cohort consisted of 435 patients who underwent TAVR using the Edwards balloon-expandable valve system (Edwards Lifesciences; Irvine, CA) and 93 patients who underwent TAVR using the Medtronic Evolut (Medtronic; Minneapolis, MN) self-expanding prosthesis (50 patients got Evolut R, and 43 patients got Evolut Pro).
• Key clinical endpoints were 30-day PPM implantation rates.
• Exclusion criteria included patients with pre-existing pacemaker, valve-in-valve procedures, and pre-emptive PPM implantation in 1 patient with a right bundle branch block.

Key Findings

• PPM implantation occurred in 32/400 (8%) of the balloon-expandable valves and 3/87 (4.6%) of the self-expandable valves (3 who had Evolut R valves and 1 who had Evolut Pro valve; p = 0.13; statistically non-significant).
• Indications for PPM implantation included complete heart block or slow atrial fibrillation.
• 10 patients within the self-expandable group developed new left bundle branch block.
• Mean valve implantation depth was 4.27 ± 1.59 mm as measured below the non-coronary cusp for the self-expanding group.

Conclusions

• This retrospective analysis of THVs for severe aortic stenosis showed rates of PPM implantation that were much lower than previously published reports for self-expanding prosthesis by maintaining an implantation depth between 3 and 5 mm below the aortic annulus in an RAO/CAU or cusp-overlap projection.
• There was no significant difference between self-expanding and balloon-expanding valve PPM implantation rates after adjustment for various patient-level and procedural characteristics. 

Systematic Approach to High Implantation of SAPIEN-3 Valve Achieves a Lower Rate of Conduction Abnormalities Including Pacemaker Implantation³

Key Question

• To evaluate whether higher implantation of balloon-expandable Edwards SAPIEN 3 (Edwards Lifesciences; Irvine, CA) prosthesis affects clinical outcomes and conduction abnormalities in patients undergoing TAVR.

New Technique (High Deployment)

• 1) Valve deployment in the RAO/CAU projection post removal of the parallax after advancement of the SAPIEN 3 valve across the stenotic aortic valve, 2) positioning the SAPIEN 3 valve by aligning the radiolucent line superior to the lower struts to the non-coronary cusp, and 3) positioning a catheter at the base of the non-coronary cusp to identify the lowest position of the aortic sinus.

Characteristics

• A total of 1,028 patients was included in a retrospective analysis of patients undergoing TAVR using Edwards SAPIEN 3 prosthesis at a single center from April 2015 to December 2018.
• The cohort consisted of 406 patients who underwent TAVR using a high-deployment technique as described above and 622 patients who underwent TAVR using a conventional technique (deployment in coplanar 3-cusp view in LAO with slight cranial angulation).
• Key clinical endpoints were as per the Valve Academic Research Consortium-2 criteria.
• Exclusion criteria included patients with pre-existing pacemaker who were not included in the endpoint analysis of new PPM implantation or new conduction disease deficits, non-transfemoral access, and valve-in-valve procedures.

Key Findings

• Successful implantation was achieved in 100% of cases in both groups, with an implantation depth of 1.5 ± 1.6 mm in the high-deployment technique and 3.2 ± 1.9 mm in the conventional deployment technique (p < 0.001).
• Need for PPM implantation within 30 days following TAVR was lower in the high-deployment technique group versus the conventional deployment group (5.5% and 13.1%, respectively; p < 0.001).
• Post-TAVR, new-onset complete heart block and new-onset left bundle branch block rates were lower in the high-deployment technique group versus the conventional deployment group: 3.5% versus 11.2% (p < 0.001) and 5.3% versus 12.2% (p < 0.001), respectively.
• Multivariable analysis demonstrated that the high-deployment technique independently predicted 30-day PPM implantation (odds ratio 0.439; 95% confidence interval, 0.246-0.781; p = 0.005) and that history of pre-existing right bundle branch block, first-degree atrioventricular block, and a larger valve size all were all predictors of higher risk of PPM implantation.
• Among the high-deployment technique and conventional groups, there were similar rates of aortic regurgitation post-TAVR at 1-year follow-up: mild aortic regurgitation was 16.5% versus 15.9% (p = 0.804), and moderate-to-severe aortic regurgitation was 1% versus 2.7% (p = 0.081). However, the peak and mean gradients at 1-year follow-up were slightly elevated in the high-deployment technique group: 13.1 ± 6.2 versus 11.8 ± 4.9 mmHg (p= 0.042) and 25 ± 11.9 versus 22.5 ± 9 mmHg (p= 0.026). Dimensionless valve index was similar in both groups: 0.47 ± 0.15 versus 0.48 ± 0.13 (p= 0.772).
• During post-dilation, 1 patient in the high-deployment technique group had valve embolization due to loss of pacemaker capture with no significant difference among the 2 groups (p = 0.216).

Conclusions

• This single-center study demonstrates that a high-deployment technique can achieve lower rates of PPM implantation and conduction defects using balloon-expandable valves compared to a conventional deployment technique without a statistically significant increase in adverse clinical outcomes, aortic regurgitation, or valve embolization between the two groups.
• This technique should be further evaluated in larger, multicenter studies to assess whether operator reproducibility of the high-deployment technique can lead to decreased rates of PPM implantation and conduction disturbances post-TAVR.

Analysis

Both these manuscripts assessing the rates of conduction defects post-TAVR show decreased rates of new PPM implantation at 30 days in RAO/CAU technique compared to previous literature using an annular plane projection. It is important to note that apart from depth of valve implantation, PPM has been associated with shorter membranous septum length, pre-existing conduction disease (notably right bundle branch block), as well as higher degree and distribution of calcium on the non-coronary cusp.

Conceptually, in the RAO/CAU projection, the non-coronary cusp is the lowest cusp versus the right and left coronary cusps in most patients (excluding some patients with horizontal aorta). Therefore, for balloon-expandable prosthesis (in particular SAPIEN 3 prosthesis), having the radiolucent line at the non-coronary cusp will allow valve deployment to be achieved at a 90:10 ratio of valve in the aorta to the LVOT as opposed to a conventional 70:30 or 80:20 ratio in a co-planar view. However, several factors need to be taken into consideration before this method is generalized to all patients. For example, there are instances in which the valve grips the heavy calcium on the non-cusp leaflet which then leads to differential foreshortening of the SAPIEN 3 prosthesis with final deployment of 80:20 or even 70:30 on the non-cusp side but 95:5 or 100:0 deployment on the left cusp side, thus risking missing the annulus on that side. In addition, if the valve is significantly undersized, this method can present challenges because foreshortening is much higher. Finally, deploying higher to 90:10 may risk or exclude future valve-in-valve options for certain low-risk patients, especially if the valve and sinotubular junction sizes are similar (risk of sinotubular junction sequestration) with short sinotubular junction heights.

In terms of self-expanding prosthesis (Evolut in particular), RAO/CAU technique is extremely useful for several reasons. Firstly, most of the time in the LAO technique, the operators have to change the projection to LAO/CAU to correct the parallax in the Evolut system. This leads to significant foreshortening of the aorta/LVOT anatomy, leading to deeper implantation compared to what is observed fluoroscopically. The RAO/CAU projection elongates the LVOT (similar to 3-chamber view on echocardiogram) and thus allows more accurate assessment of the depth of implantation. Secondly, because the Evolut is slowly deployed, the tendency of the valve in most instances is to dive toward the LVOT. Therefore, starting deployment either in the center of the pigtail or with just the nose-cone of the valve in the LVOT helps to control the depth without injuring the LVOT. These findings and the technique will be further tested in the Optimize PRO Transcatheter Aortic Valve Replacement Post Market Study.⁴

In conclusion, decreasing the degree that the THV is within the LVOT can help diminish forces on the conduction apparatus and atrioventricular node leading to lower rates of conduction abnormalities and PPM implantation. Ss demonstrated by these two studies, understanding the anatomical considerations as well as the angiographic projections necessary to achieve a reduction in parallax and valve deployment aligned with the radiolucent line in the RAO/CAU projection (specifically in balloon-expandable valves) can lead to lower rates of conduction abnormalities and PPM implantation. Safety considerations of these techniques in terms of risk of valve embolization as well as aortic regurgitation were acceptable in these studies but need to be further validated. Finally, use of this technique is not yet well-studied in bicuspid aortic valve stenosis, where calcium deposition and eccentricity can vary, altering both the implantation of THV and post-TAVR hemodynamics.

References

1. Faroux L, Chen S, Muntané-Carol G, et al. Clinical impact of conduction disturbances in transcatheter aortic valve replacement recipients: a systematic review and meta-analysis. Eur Heart J 2020;41:2771-81.
2. Pisaniello AD, Makki HBE, Jahangeer S, Daniels MJ, Hasan R, Fraser DGW. Low Rates of Permanent Pacing Are Observed Following Self-Expanding Transcatheter Aortic Valve Replacement Using an Annular Plane Projection for Deployment. Circ Cardiovasc Interv 2021;14:e009258.
3. Sammour Y, Banerjee K, Kumar A, et al. Systematic Approach to High Implantation of SAPIEN-3 Valve Achieves a Lower Rate of Conduction Abnormalities Including Pacemaker Implantation. Circ Cardiovasc Interv 2021;14:e009407.
4. Optimize PRO Study (ClinicalTrials.gov). December 16, 2020. Available at https://clinicaltrials.gov/ct2/show/NCT04091048. Accessed January 24, 2021.

Clinical Topics: Arrhythmias and Clinical EP, Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Valvular Heart Disease, Implantable Devices, EP Basic Science, Aortic Surgery, Cardiac Surgery and Arrhythmias, Cardiac Surgery and VHD, Interventions and Imaging, Interventions and Structural Heart Disease

Keywords: Transcatheter Aortic Valve Replacement, Aortic Valve Insufficiency, Atrioventricular Node, Heart Valve Prosthesis, Constriction, Pathologic, Bundle-Branch Block, Aortic Valve, Aortic Valve Stenosis, Heart Valve Diseases, Calcinosis, Aorta, Hemodynamics, Bundle of His, Atrioventricular Block, Heart Conduction System, Pacemaker, Artificial, Tomography

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