Author + information
- Alec Vahanian, MD∗ (, )
- Bernard Iung, MD and
- Dominique Himbert, MD
- ↵∗Reprint requests and correspondence:
Dr. Alec Vahanian, Cardiology Department, Bichat Hospital, University Paris VII, 46 Rue Henri Huchard, Paris 75018, France.
Aortic stenosis (AS) is the most frequent type of valve disease in Europe and North America and often requires hospitalization and intervention. Until the last decade, the only curative treatment available was surgical aortic valve replacement (AVR) but since 2002, transcatheter aortic valve implantation (TAVI) has emerged as an alternative treatment for selected high-risk patients. Thus, the evaluation of the number of potential candidates for this new technique has important public health implications.
Osnabrugge et al. (1), in this issue of the Journal, report a comprehensive literature search to assess the prevalence of aortic stenosis in patients over the age of 75 years. They reviewed 7 studies including 9,723 patients and found a high prevalence of severe AS: 3.4%. This number clearly illustrates the magnitude of the problem (2). Despite differences in the degree and definition of AS severity between series, this estimation seems robust because it relies on consistent estimations across studies.
The second finding is that 75% of the patients with severe AS were considered to be symptomatic. There could be caveats in this estimation because, in the elderly population, it could be difficult to establish that the symptoms are related to AS and not to comorbidities. In addition, many patients who claim to be asymptomatic are in fact symptomatic when exercise testing is performed.
As regards the management strategy, this study showed that as many as 40% of patients with symptoms and severe AS were not treated surgically. This figure stresses the under-treatment of high-risk patients with AS (3). Here, again, a word of caution is necessary because the studies quoted are heterogeneous as regards the period of time covered, the evaluation of the degree of stenosis, and symptoms, which may result in marked differences in the percentages of patients who were not referred to surgery.
The ultimate finding is that simulations suggest that among the patients not treated surgically, 40% received TAVI. That led the investigators to extrapolate that as many as 300,000 elderly patients with AS are TAVI candidates across Europe and the United States. Despite the careful methodology used in this study, in particular analysis of sensitivity that limits the impact of the extrapolation, it requires some comment.
The estimation of the percentage of patients referred for TAVI has limitations due to the limited number of series and, more importantly, the temporary variations with their inherent consequences on indications for intervention and the choice of technique. For example, in the very early days, the procedure was only performed on inoperable patients, whereas we are now seeing an undesired shift to performing the procedure for intermediate-risk patients despite the current recommendations (4). In addition, patients may be denied surgery according to inappropriate criteria; in other words, not because of a high risk for surgery but because of older age or left ventricular dysfunction without comorbidities, and these patients should be considered as candidates for surgery rather than TAVI for the time being.
More generally speaking it is acceptable to state that 40% of patients in the study should be assessed for the need and feasibility of TAVI; however, it is difficult to precisely evaluate the number of “TAVI candidates” from meta-analysis because the decision for TAVI requires a careful individual evaluation of each patient in this population by a heart team composed of cardiologists, surgeons, imaging specialists, and other noncardiologists if necessary. The decision-making process by the heart team should supersede a strategy based only on risk scores, which are helpful but far from perfect for patient selection in this patient population, in part because surgery may be high risk or even contraindicated because of comorbidities, which are not included in the contemporary risk scores (4). We have to work to define not only better risk scores to assess the risk of surgery in the contemporary population but also specific TAVI risk scores.
Among the patients denied for surgery, some should not be treated by TAVI because their life expectancy is too short due to comorbidities, and it is unlikely, and probably undesirable, that a larger proportion of such patients will be treated by TAVI in the future because the procedure would not improve their life expectancy or, even more so, their quality of life. We need here to refine the analysis of co-morbidities and especially the evaluation of frailty. Conversely, it is likely that the indication will be extended to lower risk patients because of a better knowledge of the results of TAVI with longer term follow-up and more refined technology. Although we do not yet have sufficient evidence, new trials such as PARTNER (Placement of Aortic Transcatheter Valves) II and SURTAVI (Surgical Replacement and Transcatheter Aortic Valve Implantation) are on the way to answer this question. We also need studies to investigate whether the indications for TAVI can be extended to patients with relative contraindications such as low left ventricular ejection fraction, associated coronary disease, bicuspid valve, bioprosthesis failure, and perhaps aortic regurgitation. Overall, the respective use of TAVI versus surgery will increase in the future, although it is too early to say for certain when and, more importantly, to what extent.
Finally, the regulatory aspects significantly impact the use of TAVI as shown by the differences in the use of TAVI in Europe and the United States: the estimation of the proportion of patients treated by TAVI is 40% in the European Union and 27% in the United States. In addition, in Europe, where this technology is widely used, the economic situation reflected by the volume-indexed gross domestic product and reimbursement modalities does have an important impact on the use of TAVI and explains variations across countries: in 2011, TAVI was performed in 97 per million inhabitants in Germany versus 35 in France and 19 in the United Kingdom (personal communication, D. Mylotte, MD, American College of Cardiology, San Francisco, March 2013).
Thus, taking into account the magnitude of the public health problem that is represented by the management of elderly patients with severe AS and the possible implications of widening the indications for TAVI in the years to come, it is imperative to improve our knowledge. The study by Osnabrugge et al. (1) is an important contribution; however, as TAVI moves forward, we need actual figures and must perform contemporary prospective observational studies to accurately assess the number of possible candidates for TAVI. These studies should include systematic and precise assessment of the severity of AS using echocardiography according to the recommendations of the scientific societies (4). These registries should be “global,” that is to say, they should prospectively record all types of management: patients treated medically, by TAVI, or by surgery.
There are several comprehensive nationwide registries for TAVI (5). There are fewer registries including surgery and TAVI, such as the recent German Aortic Valve Registry in Germany (personal communication, C. W. Hamm, ESC Annual Congress, August 2012), which shows that TAVI represents 28% of the total interventions in AS. However, we lack registries showing all management strategies, with the exception of a Spanish registry (personal communication, M. Martinez-Selles, ESC Annual Congress, August 2012) prospectively performed in octogenarians with symptomatic AS and showing that 46% were managed medically, 26% by AVR, and 28% by TAVI.
These efforts should be encouraged at the level of the scientific societies. Such evaluation, which should be dynamic to take into account the potential evolution of indications and thereby changes in patient population, is the only means of ascertaining the contemporary impact of AS management on public health and also of checking consistency between guidelines and practice. It would also be a useful complement to the randomized trials to provide us with the best evidence to support TAVI and allow the harmonious development and dissemination of this promising technique.
↵∗ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
Dr. Vahanian has received speaker's fees/honoraria from Edwards Lifesciences; is on the Advisory Boards of Medtronic and St. Jude Medical; and is a consultant to Abbott Vascular and Valtech. Dr. Iung has received consultant fees from Servier, Boehringer Ingelheim, Bayer, Valtech, and Abbott; and speaker's fees from Edwards Lifesciences. Dr. Himbert is a proctor for Edwards Lifesciences and Medtronic.
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