Author + information
- Alec Vahanian, MD⁎ ( and )
- Dominique Himbert, MD
- ↵⁎Reprint requests and correspondence:
Dr. Alec Vahanian, Cardiology Department, Hôpital Bichât, 46 Rue Henri Huchard, 75018 Paris, France
Transcatheter aortic valve implantation (TAVI) was introduced 8 years ago for the treatment of aortic stenosis and has since spread worldwide, with over 30,000 cases performed. Current evidence suggests that TAVI is the best option for inoperable patients and represents a reasonable alternative in high-risk patients for whom a heart team chooses TAVI over surgery (1,2). Balloon aortic valvuloplasty (BAV), which previously had limited indications because of its limited efficacy in improving the natural history of the disease, has experienced a revival with the development of TAVI as part of the procedure.
Over time, the TAVI technique has been refined due to the increased experience of operators and improvements in technology. There is a trend toward simplification of the transfemoral procedure moving from general anesthesia and surgical vascular access to sedation, local anesthesia, and a full percutaneous approach. It is in this context that the paper by Grube et al. (3) in this issue of JACC: Cardiovascular Interventions proposes, for the first time, to perform TAVI without BAV, which has been recommended as a preliminary step (2).
This study is a pilot multicenter series of 60 patients who underwent TAVI using the self-expandable Medtronic CoreValve (MCV) (Medtronic, Minneapolis, Minnesota) device via a transfemoral approach. The results obtained with the “simplified approach” were compared with a historical control group; however, the value of this comparison suffers from several methodological limitations and will not be taken into account during the rest of the discussion.
Performing BAV before TAVI may have several theoretical advantages.
BAV can be used as a rehearsal, before the final phase of positioning and releasing the prosthesis, allowing a final assessment of the effectiveness of rapid pacing to lower the transaortic flow. This step is crucial when using the balloon expandable prostheses and of less importance with the MCV.
Aortography during BAV enables a final measurement of the aortic annulus in cases where doubts persist as regards the choice of the size of the prosthesis after echocardiography and/or multislice computed tomography.
BAV “cracks” the nodular calcification and stretches the aortic wall, which may have several advantages for the subsequent performance of TAVI: easier crossing of the heavily calcified valve by the device and better deployment of the stented valve allowing for better hemodynamics and less paravalvular regurgitation. This “preparation” was no doubt important for crossing the valve when using the first-generation devices of 24- to 26-F. However, in the present series, the low profile of the 18-F MCV device allowed for an easy crossing because technical success was high (97%). The radial force of the device was sufficient, in itself, to obtain satisfactory post-implantation mean gradients and valve areas. By contrast, the findings in this study do not show convincingly that the simplified approach carries an acceptable risk of aortic regurgitation (AR). Overall, the incidence of any regurgitation seems in line with the expected number (AR was present in 82% of cases), but the frequency of moderate AR (57%) appears high, even more so when taking into account the need for post-dilation in 17% of cases, mostly for AR >2+. In this respect, the design of the study does not allow firm conclusions as regards the comparison with the standard technique, which would require a centralized evaluation of AR and a randomized design that could also take into account the degree of calcification and the distribution of calcium, which may have an impact. In addition, it is not possible to extrapolate the findings obtained here with MCV, where the valve is supra-annular and may theoretically be less affected by a suboptimal deployment at the level of the aortic annulus, to the balloon-expandable prosthesis where the valve is intra-annular.
Conversely, the avoidance of BAV before TAVI may have several advantages:
Reducing the duration of the procedure should always be aimed at in this elderly and high-risk population especially if general anesthesia is used. However, performing BAV is not the longest part of TAVI; it takes only a few minutes.
Another theoretical advantage is the reduction in costs in cases where no redilation is needed, but this has a limited impact on the global cost of TAVI, which, currently, is largely driven by the price of the prostheses.
Not performing BAV may avoid any need for rapid pacing, which could be deleterious in patients with very poor left ventricular function. This remark is not applicable to balloon expandable valves where pacing is mandatory. Finally, there are specific balloons that can be used to perform BAV without pacing.
More importantly, even if the risks of BAV are now reduced in comparison with historical series, BAV carries a risk that may add to that of TAVI and that should not be underestimated in this population (4–6). This does not concern the vascular complications because most teams perform BAV when the large sheath, which will be used for introduction of the prosthesis, is already in place.
The risk of stroke is around 2%, conversely the additional manipulations for crossing the native valve without dilation may increase this risk. Tamponade, which may be due to annular rupture, may occur in 1% to 2% of patients. It is speculative to say that annular rupture, which occurs during BAV before TAVI would not have occurred during implantation of the prosthesis itself, if sizing is properly done. Tamponade may also result from perforation related to manipulation of the stiff guidewire positioned in the apex of the left ventricle. BAV seldom induces severe AR (2%), which could be poorly tolerated and could compromise the hemodynamic condition if TAVI is not speedily performed, the prosthesis being ready before BAV has been started. The trend is now to perform BAV with an undersized balloon to avoid these 2 latter complications.
BAV may induce, per se, aortic valve block. This should not compromise the performance of TAVI if pacing is readily available. It is difficult, from the data in the literature, to know exactly how BAV-induced aortic valve blocks play a role in the overall pacemaker implantation; however, the U.K. registry shows that balloon pre-dilation is independently associated with the need for pacemaking after TAVI (7).
Overall, Grube et al. (3) should be congratulated for, once again, pioneering a new procedural step in the short, but very lively, history of TAVI. This pilot study is provocative in suggesting a further simplification of TAVI. However, the conclusions as regards the efficacy and risks of the “simplified approach” versus the standard approach are only preliminary due to the limited number of patients included, and the nonrandomized design of the study. In addition, the findings of this pilot study using the MCV device should not be automatically translated to the other commercially available device, even if its profile is also 18-F, as the principle, that is, balloon-expandable versus self-expandable prosthesis, is different.
Thus, TAVI can be done without balloon pre-dilation when using the MCV device; however, it is not yet established if it should be done. In addition, BAV is likely to remain as a bridge to TAVI in unstable patients, in those with uncertain indication (5,6), or for after dilation in certain circumstances of underdeployment after TAVI.
Dr. Vahanian has received speaker fees/honoraria from Edwards Lifesciences, and is a member of the advisory boards of/consultant for Abbott, Medtronic, and Valtech. Dr. Himbert has been a proctor physician for Edwards Lifesciences and Medtronic Inc.
↵⁎ Editorials published in JACC: Cardiovascular Interventions reflect the views of the authors and do not necessarily represent the views of JACC: Cardiovascular Interventions or the American College of Cardiology.
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