Transcatheter Aortic Valve Replacement: Doc, Is This Technology for Me?

Regardless of the merit of a new medical device, it does not take long for patients or relatives to inquire about new technology that could potentially be used to their advantage. However, when asked by an experienced and generally skeptical cardiology colleague who underwent aortic valve replacement with a bioprosthetic valve more than 10 years ago (with excellent results) whether a percutaneous valve may be an option for him in the event of prosthetic failure, two aspects of this new technique become apparent. First, it has already become a real treatment option and, second, specialists who frequently manage patients with aortic valve disease better become well prepared to answer important questions regarding this new technology such as patient suitability and limitations, current periprocedural complication rates and data regarding intermediate and long-term results, as well as potential improvements that are expected with technology currently under development. Two factors determine patient suitability: 1) the anatomy of the iliofemoral vasculature and the aortic valve and its surroundings; and 2) the patient’s clinical condition which dictates perioperative risk for conventional surgical valve replacement. Akin et al, in the February 2010 issue of Vascular Disease Management, present an excellent review on the clinical and anatomical appropriateness for transcatheter aortic valve replacement emphasizing a multidisciplinary approach to patient selection that not only takes into account the quantitative assessment via conventional surgical risk scores (high risk is typically a projected mortality of > 20% by EuroSCORE and > 10% by STS score), but also the clinical variables that are clearly associated with a high surgical risk but not part of traditional scores (e.g., porcelain aorta, chest radiation, previous aorto-pulmonary bypass). The authors appropriately point out that, currently, given the excellent results with conventional surgery, patients who are not considered to have a high surgical risk should not be offered percutaneous treatment merely due to patient preference. Both del Valle-Fernandez et al and Akin et al review the anatomical requirements for transcatheter valve replacement, particularly with the CoreValve, the most important of which are the maximum width of the ascending aorta, the size of the aortic annulus, the degree of aortic regurgitation, annulus-to-aorta angle, sinus of Valsalva height, the aortic root diameter and the position of the coronary artery ostia. In addition, the iliofemoral circulation needs to be of sufficient diameter and configuration to accommodate the sheath. However, an insufficient iliofemoral circulation does not preclude the use of an alternative vascular access (via the axillary/subclavian route) or the less invasive surgical transapical approach.

In the previous January 2010 issue, Gerckens et al described their results with the trans-subclavian approach,¹ and in this issue, Dr. Doss reports on the approach to transapical aortic valve replacement and summarizes the currently available data on more than 1,000 patients. Similar to the transfemoral technique, this approach is rapidly evolving and, though a hybrid operating room with readily available capabilities to establish on-pump support is essential, conversion to on-pump has become uncommon in the hands of experienced multidisciplinary teams. Regarding available experience with procedural success, periprocedural outcomes and long-term results, it is safe to say that transcatheter aortic valve replacement has been performed in well over 8,000 patients worldwide, predominantly with the balloon-expandable Edwards-SAPIEN valve and the self-expandable CoreValve. The experience with the Edwards-SAPIEN valve was well described in the January 2010 issue by Ben-Dor et al.² In this issue, del Valle-Fernandez reviews the available experience with the CoreValve. Similar to the Edwards-SAPIEN valve, with more experience and newer-generation devices, the complication rates have declined significantly. Though no randomized or controlled data are currently available, as outlined by del Valle-Fernandez et al, more recent registry data of well over 1,000 patients suggest a procedural success rate > 95%, a procedural mortality rate in the low single digits and a 30-day mortality rate of 3 Non-fatal complications include conduction abnormalities, with an estimated incidence of complete atrioventricular block of 25%,⁴ frequently requiring permanent pacemaker implantation and aortic regurgitation, which is described in more than 50% of patients5 and occasionally improves after valve postdilatation. It is only infrequently of immediate clinical consequence,⁵ however, the long-term effect of this is unknown. Device malposition is a more serious problem and may lead to impingement of the anterior mitral leaflet resulting in mitral valve dysfunction or device migration.⁶ Both frequently used current devices, the Edwards-SAPIEN valve and the CoreValve, cannot be well repositioned or retrieved after deployment. This problem is being addressed by several new devices that are currently under investigation.

In the upcoming April 2010 issue of Vascular Disease Management, Dr. Feldman will provide an excellent overview of new devices, the design of which allows more accurate positioning, deployment without the usually necessary pacing-induced circulatory arrest, may be associated with a smaller likelihood of aortic regurgitation, and, most importantly, allows repositionability and retrievability. These are important improvements as current devices are fraught with a significant learning curve and some risk of malpositioning.⁶ Whether one is interested in the performance of the percutaneous technique or not, patients will continue to expect us to present the most current treatment options, particularly if they clearly have the ability to improve their quality of life and potentially longevity and no other surgical options are available due to clinical contraindications. The articles of the previous and current issue provide the reader with important information that clarifies the suitability for percutaneous valve replacement from the clinical and anatomical perspective, the expected procedural success rates, complication rates and intermediate-term results with the currently available devices and potential future options with new devices. This information greatly facilitates management and consultation of patients with aortic valve disease.

References

1. Gerckens U, Latsios G, Grube E. Transcatheter aortic valve implantation: Clinical experience with the self-expanding Medtronic CoreValve Prosthesis: Implantation through a trans-subclavian approach. Vascular Disease Management, 2010;7:E10–E14.

2. Ben-Dor I, Waksman R, Satler LF, Pichard AD. Edwards-SAPIEN aortic valve: Transfemoral approach. Vascular Disease Management 2010;7:E1–E9.

3. Serruys PW. Transcatheter aortic valve implantation: State of the art. Eurointervention 2009;4:558–565.

4. Laborde J. Presentation at EuroPCR 2009. 2009, Barcelona.

5. Rajani R, Kakad M, Khawaja MZ, et al. Paravalvular regurgitation one year after transcatheter aortic valve implantation. Catheter Cardiovasc Interv 2009;

6. Al Ali AM, Altwegg L, Horlick EM, et al. Prevention and management of transcatheter balloon-expandable aortic valve malposition. Catheter Cardiovasc Interv 2008;72:573–578.

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From the CardioVascular Center, Frankfurt, Germany.

Address for correspondence: Prof. Dr. Horst Sievert, CardioVascular Center Frankfurt, Seckbacher Landstrasse 65, 60389 Frankfurt, Germany. E-mail: info@CVCFrankfurt.de

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VASCULAR DISEASE MANAGEMENT 2010;7(3):E87