Aortic Valve Implantation – Developments and Challenges
Table 1: Overview of Procedural Success and Clinical Outcome of Transcatheter Aortic Valve Implantation Author
Grube et al., 200715
Type Device
Year of publication Total patients (n)
Procedural success (%) Procedural mortality (%) In-hospital mortality (%) In-hospital stroke (%) 30-day mortality (%) 30-day MACCE (%) 30-day stroke (%)
TF/TS
CoreValve 2007 86 88 6 – –
12 – –
Grube et al., 200817
TF/TS
CoreValve 2008 136 91.2 0 –
2.9
10.8 14.7 –
Piazza et al., 200820
TF/TS
CoreValve 2008 646 97
1.5 – – 8
9.3 –
MACCE = major adverse cardiac and cerebral events; TA = transapical; TF = transfemoral or transsubclavian.
deal with high-degree regurgitations occurring immediately after device deployment. In long-term follow-up, serial echocardiographic studies have consistently shown good prosthetic valve function with no structural deterioration of valve tissue.15,16,26,27
Reports on
transapical aortic valve implantation are available only for the ESP, mainly from two experienced centres.18,28
The implantation success
rate was about 90%. The majority of patients are being treated off- pump, and the rate of peri-operative conversion is 9–12%. Mortality rates range from 9 to 18%. Strokes occur in about 0–6%. Non- randomised comparison of transapical and transfemoral approaches from the SAPIEN Aortic Bioprosthesis European Outcome (SOURCE) registry and Placement of Aortic Transcatheter Valve (PARTNER EU) trial indicate a higher mortality rate for the transapical approach in selective patients with higher estimated risk than patients undergoing retrograde TAVI. Randomised studies are needed to definitively assess the superiority of one technique over the other.
Patient Selection
Optimal patient selection and pre-procedural screening play a crucial role in this context and should consist of multidisciplinary consultation between cardiologists, cardiac surgeons, anaesthesiologists and other specialists previously involved in the treatment of the patient. In previously published studies, the indication for TAVI was patients with severe (aortic valve area 20% or an STS score >10%. After publication of the first clinical results showing procedural success rates of approximately 90% and following CE approval of the two devices, 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), published a position statement29
that TAVI should be restricted
to patients at high risk or with contraindications for surgery. They underscored the point that it is too early to establish TAVI in patients who are good surgical candidates.32
Therefore, the estimation
of risk for surgery is based not only on quantitative assessment of risk scores but also on clinical judgement.
TAVI success is influenced by numerous factors including operator experience and patient selection; in particular, the operator learning curve affects the outcome in the first cases of each centre. However,
INTERVENTIONAL CARDIOLOGY
even beyond this learning period, procedural outcome varies, with procedural failure rates of approximately 5–25%. Therefore, it is of importance to identify factors that predict the outcome of TAVI in clinical practice.
In a previous publication,21 we analysed various clinical,
quantitative morphological and procedural parameters potentially affecting procedural outcome based on the combined TAVI experience of two institutions. In this analysis, the pre-procedural functional performance status of the patient was identified as an important outcome predictor for patients undergoing TAVI. This observation is of importance for future TAVI studies, as it might shift the clinical relevance of scoring systems from the historically used, more co-morbidity-based EuroScore or STS score towards functional assessment scales (frailty indices). It is not the sum of various individual co-morbidities that predicts the procedural risk, but rather their consequences for the functional and clinical status of the patient.
This finding of a correlation between pre-procedural frailty and post- procedural outcome may open the door towards inclusion of a healthier patient population. To date, it has been uncertain whether a complication after TAVI is procedure-related – suggesting that the surgical gold standard might have been a better alternative – or mainly related to the patient’s functional status and co-morbidities. The current data support the notion that the healthier the patient is before the procedure, the better the outcome afterwards. Accordingly, the complication and success rates of TAVI, as currently reported in patients at high surgical risk, cannot be translated to lower-risk patients with a good functional performance status. TAVI in patients at low surgical risk will almost certainly yield better feasibility and safety results than those currently reported.
Limitations
Degenerative, formerly senile, aortic stenosis represents the only considerable indication for TAVI in a selective, high-risk patient population. Aortic insufficiency embodies another potential target for the use of transcatheter bioprostheses. However, an only mildly calcified native valve may hinder sufficient anchoring of the prosthesis and, moreover, the often-associated dilatation of the ascending aorta might contraindicate the sole treatment of the valve problem. Nevertheless, in patients with prior surgical valve replacement (biological valve), TAVI appears to emerge as a valuable treatment option.
79 TF/TS
CoreValve 2010 168 90.5 –
11.9 3.6 – – –
201022 TF/TA
Edwards 2010 1,038 93.8 – – –
8.5 –
2.5
Buellesfeld et al., Thomas et al., Rodés-Cabau 201021
et al., 201023 TF/TA
Edwards 2010 339 93.3 1.7 – –
10.4 –
2.3
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