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Clinical outcomes of patients with estimated low or intermediate surgical risk undergoing transcatheter aortic valve implantation

In the 1st July Issue of the European Heart Journal, an article from Wenaveser et al. addresses the issue of transcatheter aortic valve implantation (TAVI) in patients at low or intermediate risk for surgery (1).

Valvular Heart Diseases

From a single-centre series of 389 consecutive patients undergoing TAVI, the STS score was used retrospectively to categorize patients into 3 risk classes: low risk defined by an STS score < 3% (n=41), intermediate risk defined by an STS score between 3 and 8% (n=254) and high risk defined by an STS score >8% (n=94). The respective values of the logistic Euroscore were 13%, 22% and 35%. Thirty-day mortality was 2.4% in low-risk patients, 3.9% in intermediate-risk patients and 14.9% in high-risk patients. Respective one-year mortality rates were 10%, 16% and 34%. The two current balloon-expandable and self-expandable prostheses were used. Most procedures (79%) used the transfemoral approach, which is consistent with most contemporary series. This paper deals with two issues which are the subject of current interest in the field of TAVI: the reliability of risk scores and the extension of indications for TAVI toward patients at lower risk.

Risk scores predicting 30-day mortality after cardiac surgery were an important component of patient selection at the beginning of TAVI, high-risk patients being defined by a logistic Euroscore > 20% and/or an STS score > 10% (2). However, growing evidence has shown that risk scores have a limited predictive performance in high-risk patients with valvular heart disease. This concerns calibration in particular, i.e. the concordance between predicted and observed mortality. The Euroscore has been shown to overestimate mortality in high-risk patients, which is consistent with the recent paper of Wenaveser et al. (3, 4). The prediction obtained with the STS score seems to be more in accordance with observed mortality (3). Testing the predictive value of the TS score is limited since the equation of the STS score is not available, which precludes the performance of retrospective calculation in large databases, although this can be easily done with the Euroscore. The Euroscore II has been recently developed and demonstrated good discrimination and calibration properties (5). An external validation in a contemporary dataset of xxx patients has shown far better calibration properties than with the logistic Euroscore in a general population of patients undergoing cardiac surgery (6). However, there was still a discrepancy between observed and predicted mortality when using the Euroscore II in high-risk patients. This suggests that risk scores are likely to face intrinsic limitations when applied to high-risk patients. The values and limitations of risk scores applied to patients with valvular heart disease, particularly those at high risk, have been analyzed in a position paper from the ESC Working Group on valvular heart disease (7). One of the reasons accounting for the potential limitations of risk scores in high risk patients is that they represent a heterogeneous population in which it is difficult to estimate the individual contribution of the different comorbidities to the operative risk. These limitations explain why recent ESC/EACTS guidelines favour the clinical judgment of the heart team over threshold risk scores for the choice between TAVI and surgical aortic valve replacement (8).

At the present time, indications for TAVI are restricted to high-risk patients (8, 9). Improvements in acute success rates and decreased incidence of complications raise the possibility of extending the indications for TAVI towards patients at lower risk. Although better results of TAVI can be expected in patients at lower risk for surgery, the paper by Wenaveser et al. has the merit of demonstrating that this is true in practice. This is a relevant contribution to the debate on the extension of indications for TAVI, but other factors should be taken into account. Surgical aortic valve replacement is now performed with low mortality rates and good long-term results in low and intermediate risk patients. Experience is still lacking with regards to the durability beyond 5 years of valve substitutes used for TAVI. In addition, growing evidence for the negative impact of post-procedural aortic regurgitation may hamper long-term results of TAVI (10, 11). In the paper by Wenaveser et al., aortic regurgitation ≥ grade 2 was present in 10% of low-risk patients and 13% of intermediate-risk patients and the rates did not differ with high-risk patients (16%). Uncertainties about the durability of valve substitutes and the impact of post-TAVI aortic regurgitation are of particular importance in patients at low and intermediate risk who are likely to have a much longer life expectancy than high-risk patients.

The findings of the present paper should therefore not be interpreted as an incentive towards expanding the indications of TAVI towards patients at lower risk. There is already a trend towards the use of TAVI in patients at lower risk, which is clearly shown in a recent paper from an experienced team (12). This trend should not be encouraged only on the basis of good immediate and short-term results of TAVI in these patients. It is necessary to compare late clinical benefit with the results of surgical aortic valve replacement. Following the example of indications for TAVI in high-risk patients, indications in intermediate-risk patients should be tested in randomized controlled trials, such as the ongoing Partner II and Surtavi trials, before being applied in practice. 


1. Wenaveser P, Stortecky S, Schwander S, et al. Clinical outcomes of patients with estimated low or intermediate surgical risk undergoing transcatheter aortic valve implantation. Eur Heart J 2013;34:1894-1905.
2. Vahanian A, Alfieri O, Al-Attar N, et al.. Transcatheter valve implantation for patients with aortic stenosis: a position statement from the European association of cardio-thoracic surgery (EACTS) and the European Society of Cardiology (ESC), in collaboration with the European Association of Percutaneous Cardiovascular Interventions (EAPCI). EuroIntervention. 2008;4:193-199.
3. Dewey TM, Brown D, Ryan WH, Herbert MA, Prince SL, Mack MJ. Reliability of risk algorithms in predicting early and late operative outcomes in high-risk patients undergoing aortic valve replacement. J Thorac Cardiovasc Surg. 2008;135:180-187.
4. Brown ML, Schaff HV, Sarano ME, et al. Is the European System for Cardiac Operative Risk Evaluation model valid for estimating the operative risk of patients considered for percutaneous aortic valve replacement? J Thorac Cardiovasc Surg 2008;136:566-571.
5. Nashef SA, Roques F, Sharples LD, et al. EuroSCORE II. Eur J Cardiothorac Surg. 2012;41:734-744.
6. Barili F, Pacini D, Capo A, et al. Does EuroSCORE II perform better than its original versions? A multicentre validation study. Eur Heart J 2013;34:22-29.
7. Rosenhek R, Iung B, Tornos P, et al. ESC Working Group on Valvular Heart Disease Position Paper: assessing the risk of interventions in patients with valvular heart disease. Eur Heart J. 2012;33:822-828.
8. Vahanian A, Alfieri O, Andreotti F, et al. Guidelines on the management of valvular heart disease (version 2012): The Joint Task Force on the Management of Valvular Heart Disease of the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS). Eur Heart J. 2012;33:2451-2496.
9. Holmes DR, Jr., Mack MJ, Kaul S, et al. 2012 ACCF/AATS/SCAI/STS expert consensus document on transcatheter aortic valve replacement. J Am Coll Cardiol. 2012;59:1200-1254.
10. Gilard M, Eltchaninoff H, Iung B, et al. Registry of transcatheter aortic-valve implantation in high-risk patients. N Engl J Med. 2012;366:1705-1715.
11. Kodali SK, Williams MR, Smith CR, et al. Two-year outcomes after transcatheter or surgical aortic-valve replacement. N Engl J Med. 2012;366:1686-1695.
12. Lange R, Bleiziffer S, Mazzitelli D, et al. Improvements in transcatheter aortic avlve implantation ouitcomes in lower surgical risk patients. J Am Coll Cardiol 2012;59:280-287.

Notes to editor

Presented by Bernard Iung, Cardiology Department, Bichat Hospital, Paris, France
Clinical outcomes of patients with estimated low or intermediate surgical risk undergoing transcatheter aortic valve implantation.
Wenaweser P, Stortecky S, Schwander S, Heg D, Huber C, Pilgrim T, Gloekler S, O'Sullivan CJ, Meier B, Jüni P, Carrel T, Windecker S.
Source Department of Cardiology, Swiss Cardiovascular Center, Bern University Hospital, Switzerland.
Eur Heart J. 2013 Jul;34(25):1894-905. doi: 10.1093/eurheartj/eht086. Epub 2013 Mar 13.

The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.

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