Transcatheter valve implantation (TAVI) was one of the dominant topics at the EuroPCR congress. Among the results presented were the two-year follow-up data from an international study and five national registries. The results were considered “encouraging” in patients at high risk for surgery. The questions now are whether benefits will be sustained in the long term and also whether indications can be expanded to a younger population.
Ulrich Gerckens, Helios Heart Center Siegburg, Germany, presented the two-year safety and effectiveness results, which evaluated 126 patients at nine centres in Europe and Canada. Patients were implanted with the 18F CoreValve system (Medtronic).
“These pivotal trial results provide important evidence and confidence to physicians that CoreValve is an effective long-term treatment alternative for many patients with severe aortic stenosis who are considered at high surgical risk or inoperable,” he said.
Of the 126 enrolled, 62 were followed for at least two years, 48 expired, five were lost to follow-up and 11 had not had two-year outcomes reported yet. Gerckens reported an 83.1% technical success rate.
In terms of safety, the results showed that all-cause survival at two years was 59.7%, compared with 71.9% at one year. There were also no valve migrations, frame fractures or structural valve deterioration, Gerckens reported, and there was one paravalvular leak.
On effectiveness data, Gerckens told delegates that, at two years, 73% of patients experienced an improvement in their heart failure symptoms (one or more NYHA class improvement). The valve opening area increased 2.5 times from baseline on average and remained stable at two years. Resistance to forward flow through the valve (peak and mean valve gradient) was decreased by 75–80%.
Gerckens said that the two-year results were encouraging in this high-risk, elderly cohort. Overall survival was almost 60%, he told delegates, and the cardiac death rate was 26%. Regarding effectiveness, he concluded that there had been sustained improvements in functional class and haemodynamic measures and no evidence of structural deterioration or migration.
“Without valve treatment this patient population faces a 50% chance of survival from cardiovascular events at two years. In contrast, patients who received CoreValve have a greater chance of survival and overall better heart function,” Gerckens said.
Data from five TAVI national registries (Italy, UK, Germany, Belgium and France) were also presented at EuroPCR. These studies included clinical results on more than 3,000 CoreValve patients. The studies demonstrated sustained positive clinical outcomes following the procedure – at six months, one year and one study out to two years.
The safety and efficacy of CoreValve was shown with success rates above 97% across the registries with 30-day mortality rates ranging from 5% to 15%. One-year survival rates ranged from 79% to 82%, exceeding expected survival for medical management and similar to survival rates seen in high-risk surgical repair for this patient population.
“The two-year registry results are very encouraging and show continued good outcomes in these very high-risk patients, without any structural valve failures,” said David Hildick-Smith, Sussex Cardiac Centre, Brighton, UK.
The CoreValve system, which received CE mark in March 2007, is typically delivered through the femoral artery. It is not available in the USA.
Cardiovascular News asked participants of the EuroPCR session ‘TAVI: mid- and long-term clinical outcomes’ their opinion on the new data.
Do results presented so far put TAVI as a first treatment choice in high-risk patients not suitable for conventional surgery?
Anna Sonia Petronio, University of Pisa, Italy: The results from the European registries certainly put TAVI as the best choice for elderly patients at high surgical risk. It was encouraging to see that procedural results and medium-term survival were really good and similar among registries, and that hospital stay was uniformly shorter than for surgical AVR. The use of local anaesthesia, the lack of extracorporeal circulation, and the percutaneous approach reduce the periprocedural complications, particularly with regards to respiratory and kidney failure in these fragile elderly patients. It will be very important to wait and look carefully at long-term follow-up, and observe the durability of these new biological valves.
David Hildick-Smith: High-risk patients not suitable for conventional surgical aortic valve replacement should certainly now be considered for TAVI.
Marco Barbanti, Ferrarotto Hospital, Catania, Italy: In the last years, TAVI has evolved rapidly into a reproducible procedure with convincing clinical benefits, so that it can be considered as a first treatment choice in high-risk patients denied surgery. However, much more needs to be done in guiding patient selection, predicting those most and least likely to benefit from this procedure. In elderly and frail patients, operative outcomes should take into account the potential gain of comfort in daily life.
Gérard Fournial, Hôpital Rangueil, Toulouse, France: The main problems resulted from the high level of pacemaker implantation, which occurred in 8–34% of the cases depending on valve device, and criteria of indication (prophylactic implantation in some centres). These economical consequences have to be taken into account in this expansive treatment due to valve fee. Paravalvular insufficiency could be an issue in mid- and long-term follow-up because of myocardial damage, hemolysis and risk of endocarditis; these issues are well known after valvular surgery. Even though TAVI is less invasive than open heart surgery, it needs a safe environment under general anaesthesia. Its use is strongly recommended to avoid discomfort (for both patient and operator) and to deal with major complications such as cardiac arrest or vascular rupture. Major events depend essentially on technical problems and patient selection which need constant evaluation to improve these different issues. High procedural success, acceptable mortality rate and favourable clinical outcome at two years justify the acceptance of TAVI in very high-risk patients not suitable for conventional surgery.
Ulrich Gerckens: Compared to conservative management, TAVI appears to be the better choice for these high-risk or even non-operable patients in terms of improved functional status. Pending results from the randomised PARTNER trial, the limited data available mainly compares TAVI survival outcomes to predicted outcomes from surgical risk scores, and so far it has been comparable. Furthermore, many of these elderly patients would not have been considered for surgery due to reasons that are not accounted for within these risk scores, such as unsuitable chest or aortic anatomy. Hence we are dealing with a unique cohort of patients whereby TAVI may be the only feasible option apart from conservative management.
Is it possible to extend the indication for TAVI to lower-risk patients?
Anna Sonia Petronio: At the beginning of the TAVI experience we were forced to operate on very sick patients, almost in a compassionate use of TAVI. Probably now we would not treat some of these cases, as we have learnt to better evaluate very fragile patients. The possibility to widen the spectrum of TAVI patients by including lower risk profile ones, as well as young patients, depends not only on the improvement of the devices, but mostly on the demonstration that these new valves are durable as the surgical prostheses. I am sure that in the next one or two years there will be important technological changes that will make the procedure easier and reduce periprocedural complications, such as vascular complications, rhythm disturbances, etc. Still, the most important step will be the demonstration that TAVI valves are durable in the long-term.
David Hildick-Smith: Extension of the indications for TAVI into a lower risk cohort should be done in the context of a clinical trial. Several upcoming trials aim to recruit such patients randomised against surgery.
Marco Barbanti: At the moment it is too early to extend the indication for TAVI to a larger lower-risk population; long-term efficacy has firstly to be proved in larger and possibly randomised series before going through the next steps. There is still much to know about long-term effectiveness of this new procedure. In particular, data comparing TAVI and surgical AVR are still few and limited to retrospective analyses. Waiting for results from the PARTNER randomised trial, which likely will influence the availability and founding of TAVI for some time, it is crucial to detect the most indicated type of patients for future larger trials and studies comparing the percutaneous and the surgical approach. At the end of these stages, TAVI will have the most correct role in the standard of care for aortic stenosis.
Gérard Fournial: These encouraging results may allow the expansion of indication in less sick patients, but this evolution needs controlled trials because of unknown consequences of paravalvular insufficiency, tissue durability and stent fracture risk.
Ulrich Gerckens: If not already occurring, TAVI for lower risk patients will very likely be performed in real-world practice. My opinion is that TAVI is a feasible treatment option for these lower risk patients but because of the absence of long-term outcome results, this indication must first be carried out and tested within the boundaries of clinical trials. In addition, further developments in the TAVI technology and technique may help to extend its clinical indications, with smaller caliber delivery catheters, better positioning techniques and lesser post implantation aortic regurgitation.