Evolving indications for the use of transcatheter aortic valve implantation (TAVI) have led to a series of “paradigm shifts” in the treatment of severe symptomatic aortic stenosis, according to a position statement issued by PCR, which says that TAVI should now be favoured over surgical aortic valve repair (SAVR).
Announcing the statement at EuroPCR 2019 (20–24 May, Paris France), Stephan Windecker (Bern University Hospital, Bern, Switzerland) said: “The favourable outcomes of TAVI are consistent across the entire risk spectrum, suggesting that surgical risk estimation is no longer the basis to guide the choice between TAVI and SAVR.”
Windecker explained: “The available evidence has been extended by two recent landmark trials in the low-risk patient population which provide us now with a comprehensive picture, ranging from extreme high-risk, intermediate, to low-risk patients.” The aim of the PCR statement, he said, is to “synthesise the available evidence”. From this, three paradigm shifts can be identified.
The first of these relates to the decision-making process between TAVI and SAVR: “Because the benefits are so consistent, the risk stratification that we applied using the STS [Society of Thoracic Surgery] score to identify patients at increased risk for surgery is no longer useful. Rather than categorise patients in the extreme, intermediate, and low risk, we should rather look at the clinical and anatomical characteristics of individual patients to guide the decision-making between these two procedures.”
Secondly, the heart team will identify the best treatment option for individual patients, with transfemoral TAVI replacing SAVR as the default therapy for a greater number of patients: “Up to now, by default, in low-risk patients surgery was the therapy of choice, and TAVI was only to be considered in those patients where surgery would not be possible. In the not too distant future, a scheme will emerge where actually the question will be reversed, with any patient being considered a priori to be a TAVI candidate and surgery being reserved to cases where that is not possible,.”
The third paradigm relates to prosthetic valve choice, and is to be based upon life expectancy and valve durability: “That should be, if we look at very young patients [<50 years], preferentially a mechanical valve prosthesis in case of aortic stenosis. In patients that are above 65 years of age, a bioprosthetic valve. The discussion is not the procedure, but it is rather the valve type, and obviously there remains a grey zone of individual decision-making.”
He highlighted findings from a recent meta-analysis of seven randomised controlled trials with >8,000 patients that demonstrates a superior clinical performance for TAVI compared with SAVR. “The accumulated evidence to date shows not only non-inferiority but, in fact, superiority as it relates to those endpoints that are the most important from a patient perspective, and that is mortality, stroke, and rehospitalisation. Similarly, not only is there a clinical benefit, but there is also optimisation in terms of resource utilisation as it relates to procedure time, hospital stay, and post-procedure care.”
Published in the European Heart Journal, the meta-analysis by George Siontis (Bern University Hospital, Bern, Switzerland) et al included all randomised clinical trials comparing TAVI and SAVR among high-risk and intermediate risk patients, as well as the recent PARTNER 3 and Evolut Low-Risk Trial.
Siontis et al found that for all types of risk and valve type, TAVI showed a significant reduction in all-cause mortality compared with SAVR (hazard ratio [HR] 0.88, 95% confidence interval [CI] 0.78–0.99) at two years. “The important information,” said Windecker, “is that this benefit is irrespective of risk—high, intermediate, and low risk. There is a very consistent observation.”
TAVR also demonstrated better outcomes than SAVR for stroke (HR 0.81, 95% CI 0.68–0.98, p=0.028), and major vascular complications (HR 1.99, 95% CI 1.34–2.93), although the rate of permanent pacemaker implantation was higher with TAVI than SAVR (HR 2.27, 95% CI 1.47–3.64).
Windecker pointed out that the findings on stroke rates, “which from a patient perspective is an equally important endpoint [as mortality]”, have undergone a “notable evolution”.
“If you look at stroke, any stroke, there is a significant 19% relative risk reduction up to two years. If you just look at disabling stroke, then we have a similar point estimate with a 22% relative risk reduction … but formally it is not statistically significant.”
In addition, the relative risk reduction for mortality at two years was 17% for TAVI when access was via the transfemoral route (HR 0.83, 95% CI 0.72–0.94, p=0.032), with a “substantial” reduction in the use of hospital resources, due to reduced procedure times, intensive care unit stays, and total hospital stays.
Windecker said: “If you reduce the analysis just to transfemoral access then you see that the finding is more robust, with a 17% relative risk reduction and a more narrow confidence interval. Whereas, there is no advantage or difference to be seen with an alternative access route.”
He remarked upon the “remarkable consistency in the Partner 3 and Evolut Low Risk trials indicating superiority” on the endpoint of rehospitalisations, and added: “If you synthesise all these endpoints, then it is clear it is not just non-inferiority but also superiority.”
The statement concedes that the cost of TAVI valves mean that the cost-effectiveness of the procedure needs further study.
“There are obviously areas of remaining uncertainty,” Windecker acknowledged. “Certainly we need to be better informed regarding durability for both transcatheter and surgical valves. We do not know much about the performance of the transcatheter valves in the setting of bicuspid valve disease, and those who have concomitant relevant coronary artery disease. We still need more information as to the long-term impact of permanent pacemaker implantation; and although the low-risk trials included younger patients—the mean age was 74—certainly we would need more information as it relates to even younger patients. Finally, there is no conclusive information as it relates to the optimal antithrombotic therapy.”
However, he concluded: “There is no doubt transcatheter aortic valve implantation constitutes a major paradigm shift in the care of patients with severe symptomatic aortic stenosis. From a procedure point of view, from a risk point of view, from early outcomes and mid-term follow-up, overall, the results favour the minimal invasive technique.”