During the last decade, transcatheter aortic valve implantation (TAVI) has become the first-choice therapy for treating symptomatic severe aortic stenosis in most patients older than 80 years with suitable transfemoral access.1 However, the most common complication following TAVI remain new-onset conduction disturbances (CD).2 In recent years, several studies have shown the usefulness of a novel, modified implantation technique using a cusp overlap technique (COT), which overlaps the left and right coronary cusps and isolates the noncoronary cusp.3,4 The potential benefits of using the COT during TAVI include elongation of the left ventricular outflow tract, which provides more accurate control of the real prosthesis implantation depth, thus lowering the risk of interaction with the conduction system. Whereas early experiences of this approach using self-expanding supra-annular valves have been promising, to date, no studies have assessed the use of the COT using the self-expanding intra-annular Portico FlexNav system (Abbott Vascular, United States). The present study sought to determine whether the use of the COT during Portico FlexNav system implantation results in higher implantation depth and lower CD rates.

This was a multicenter study including consecutive patients undergoing transfemoral TAVI with the self-expanding intra-annular Portico valve with the second-generation FlexNav delivery system at 3 tertiary centers. Between July 2020 and July 2021, a total of 91 consecutive patients underwent TAVI with the Portico FlexNav system. Patients with previous permanent pacemaker implantation (PPI) were excluded (n=6), leading to a final study population of 85 patients. Of these, 42 prospective patients received a Portico valve using the COT (January-July 2021) and were compared with 43 consecutive patients who had previously received a Portico valve using the traditional coplanar 3-cusp technique (July-December 2020) (figure 1). All implantations were performed by certified operators with a previous cumulative experience of at least 25 procedures with the first-generation Portico delivery system and ≥ 5 procedures with the next-generation FlexNav delivery system. Data were collected in accordance with the ethics committee of each participating center, and all patients provided signed informed consent to undergo the procedures.

Figure 1.

Flowchart of the study population. PPI, permanent pacemaker implantation.

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Implantation technique

Preprocedural work-up for anatomic assessment and optimal implant projections were made with either 3Mensio Structural Heart (Pie Medical Imaging, Netherlands) or Heart Navigator (Philips Healthcare, Netherlands). Predilation with a balloon diameter equal to the average diameter of the aortic annulus was recommended. Patients in the conventional (coplanar 3-cusp) deployment technique underwent valve implantation as previously described.5 Implantation using the COT was performed as follows: the valve was deployed in a right anterior oblique/caudal view, using no rapid pacing or controlled pacing at 120 bpm at the discretion of the implanting physician, followed by a left anterior oblique projection (modified coplanar view) to measure the left coronary depth and position of the delivery catheter before final release (figure 2). Target implantation depth was defined as ranging between 3 and 5mm (distance from the noncoronary cusp to the inflow of the transcatheter heart valve frame) regardless of the working projection. In both groups, the final implantation depth was assessed in a left anterior oblique angiogram.

Figure 2.

Standard 3-cusp view (LAO) vs cusp overlap (RAO/CAU) technique. A-E: conventional 3-cusp implantation technique. A-C: cardiac computed tomography and baseline aortogram showing the classic coplanar projection with 3 cusps: NCC (yellow) on the left side, RCC (green) in the middle and LCC (red) on the right side. D-E: initial positioning of a Portico valve and final assessment under a 3-cusp view. F-J: cusp overlap implantation technique. F-H: computed tomography and angiogram in a RCC/LCC cusp overlap view: in this projection, the NCC (yellow) is on the left side and the RCC (green) and LCC (red) are overlapped on the right side. I-J: valve positioning and final assessment in a cusp overlap view. Dotted lines represent implantation depth (distance from the NCC to the ventricular end of the TAVI frame). CAU, caudal; LAO, left anterior oblique; LCC, left coronary cusp; NCC, noncoronary cusp; RAO, right anterior oblique; RCC, right coronary cusp.

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The present study specifically assessed the safety and efficacy of the COT during TAVI with the self-expanding intra-annular Portico FlexNav system. The main findings of the study can be summarized as follows: a) use of the COT was feasible, with high technical success and low rates of major complications, similar to those achieved with the conventional coplanar 3-cusp view, b) COT use resulted in a higher implantation depth, and c) COT use was independently associated with lower rates of new-onset CD.

The COT has been proposed for deployment of self-expanding valves to enable higher device implantation and reduce postprocedural CD. The rationale behind this fluoroscopic projection, which isolates the most inferior hinge point of the noncoronary cusp in a right anterior oblique/caudal view, relies on the fact that annular contact with self-expanding valves occurs mainly from the noncoronary cusp toward the left coronary cusp.8 The potential advantages of this approach are elimination of the delivery system parallax, elongation of the left ventricular outflow tract and shorter visual distance of the aortic annulus (minor axis), enabling a more precise assessment of the real implantation depth, with the potential to minimize the risk of injury to the conduction system.9 The majority of experiences reported so far with this approach have been performed with the supra-annular Evolut valve (Medtronic, United States). In a propensity score analysis of 444 patients treated with Evolut, use of the COT (compared with the classic implantation technique) reduced the rate of PPI (11.8% vs 21.7%; P=.03) without compromising TAVI outcomes.10 In the largest series of consecutive patients undergoing Evolut TAVI using COT (n=694), Gada et al.11 demonstrated a very low risk of PPI (< 5%) with this technique, with a low rate of major cardiac adverse events.

To date, there have been scarce data on the COT with the Portico valve. In a retrospective study analyzing the impact of the COT with different self-expanding valves, Mendiz et al.12 included 19 patients treated with Portico. Overall and in line with prior studies, COT reduced the rate of CD without compromising safety outcomes.

Our results also support the use of the COT with the Portico FlexNav system as a safe strategy, with comparable success rates and similar rates of major complications. Indeed, using this approach resulted in higher valve implantation and subsequent reduction in the rates of conduction abnormalities after TAVI, without increased risk of valve embolization or compromise of valve hemodynamics. Interestingly, incorporation of this modified working projection may reduce radiation exposure (lower fluoroscopy time), by providing a more precise visualization of the implant depth and accurate device placement, although it did not translate into a reduction of the overall length of the procedure.

In the present work, COT was barely used in valve-in-valve procedures (figure 1 of the supplementary data). Albeit less frequent, this method can also be used to treat degenerated surgical valves, since surgical prostheses are directly aligned with native aortic valve commissures and consequently the postsurgical anatomy usually matches the native anatomy. Akin to TAVI in native valves, the cusp overlap view can be obtained by isolating the bioprosthetic stent post between the left and right coronary cusps based on preprocedural computed tomography, as recently reported by Wong et al.13

Of note, residual transvalvular gradients were lower in the COT group, which may be explained by a higher positioning of the leaflets leading to more favorable hemodynamics, although this finding should be interpreted as hypothesis-generating only.

Importantly, patients in the COT group had significantly lower rates of conduction abnormalities, similarly to previous reports with other self-expanding valves. The need for PPI in the standard 3-cusp group was roughly twice that in the COT group (30% vs 14%; P=.078) although this difference was not statistically significant probably due to the limited sample size. The difference was much more noticeable when we excluded patients with pre-existing right bundle branch block (31.0% vs 7.7%; P=.011), who are at the highest risk of PPI regardless of the type of valve and implantation technique.

Finally, postdilation was associated with increased new-onset CD post-TAVI on univariate but not on multivariate analysis. Whereas valvuloplasty may increase the risk of conduction abnormalities after TAVI due to the mechanical trauma to the conduction system, no clear association has yet been identified between postdilation and new PPI.14

Application of the COT during implantation of the Portico FlexNav system is feasible and may help to achieve higher implantation depth and lower subsequent rates of new-onset CD without compromising safety outcomes or valve performance.

None.

L. Asmarats, L. Nombela-Franco, A. Regueiro and D. Arzamendi conceived and designed the analysis. L. Gutierrez-Alonso, G. Tirado-Conte, P. Cepas and E. Fernández-Peregrina collected the data. L. Asmarats and X. Millán performed the analysis. CH. Li, P. Jiménez-Quevedo and X. Freixa reviewed and edited the manuscript.

L. Asmarats, L. Nombela-Franco, X. Millán, CH. Li, X. Freixa and D. Arzamendi are proctors for Abbott. A. Regueiro is proctor for Abbott and Meril Life. The other authors report no conflicts.