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With transcatheter aortic valve implantation (TAVI) now increasingly being considered as an option for younger patients who may be at low risk for surgery, the need for long-term data charting the durability of transcatheter valves, as compared to those implanted during a surgical procedure, becomes ever more important.
The recent presentation of 10-year data from the NOTION trial—the longest-running randomised clinical study to compare outcomes among lower-risk patients undergoing TAVI using the first generation CoreValve™ (Medtronic) device versus surgical aortic valve replacement (SAVR)—is seen as a milestone moment in the continuing development of the TAVI procedure. Reported by Troels Hojsgaard Jorgensen (Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark) at the 2023 European Society of Cardiology (ESC) congress (25–28 August, Amsterdam, The Netherlands), the 10-year NOTION trial data offer important insights into long-term outcomes among lower surgical risk patients receiving either a TAVI or SAVR valve.
The data presented by Jorgensen at the ESC meeting paint a reassuring picture for TAVI in the long-term, with patients undergoing TAVI demonstrating a similar risk of all-cause mortality, stroke and myocardial infarction (MI) as those treated surgically. What is perhaps more important to learn from the 10-year NOTION data is the relative performance of the valves in terms of structural valve deterioration and bioprosthetic valve failure of the CoreValve (Medtronic) TAVI valves when compared to those implanted during surgery.
“The data we have on 10-year durability of TAVI are very scarce and what we had before NOTION were just registry-based analyses describing durability of TAVI not compared to surgery, so this is really the first time we see such a long-term outcome assessment from a randomised trial,” Mohamed Abdel-Wahab (Leipzig Heart Center, Leipzig, Germany) tells Cardiovascular News, commenting on the significance of these latest data.
Abdel-Wahab praises the quality of the execution of the trial, which was conducted at sites in Denmark and Sweden between 2009–2013, and in particular he praises the availability of 10-year follow-up data, collected from 27 patients from an initial cohort of 120 in the trial’s SAVR arm, and 34 of an initial 130 patients who underwent TAVI.
“We know from experience that it is extremely hard to get such long-term follow-up in a population of patients that are elderly and usually have multiple comorbidities,” he comments. “It is not that easy to get them back to do an echocardiographic follow-up which is the cornerstone of having a good durability assessment.”
The definition of structural valve deterioration as used in the NOTION trial is an important point to reflect on, says Abdel-Wahab, as this has been a significant area of debate. Since the commencement of the trial a consensus document on valve durability from the European Association of Percutaneous Cardiovascular Interventions (EAPCI) was published in 2017 in the European Heart Journal, defining valve durability using both bioprosthetic valve dysfunction (comprising of structural valve deterioration, non-structural valve deterioration, and bioprosthetic valve thrombosis/endocarditis) and bioprosthetic valve failure (valve-related death, aortic valve reintervention, and severe haemodynamic structural valve dysfunction).
In the trial, structural valve deterioration was considered to be present if the patient had a transprosthetic mean gradient ≥20mmHg, an increase of 10mmHg from three months, or more than mild intraprosthetic aortic regurgitation. The NOTION investigators found the risk of structural valve deterioration was increased in patients with a surgical bioprosthesis at 37.7%, when compared to patients with a transcatheter heart valve, whose risk was around 20.2%.
Detailing findings on the composite risk of bioprosthetic valve failure, comprising the risk of valve-related death, the need for aortic valve reintervention, or the development of severe structural valve deterioration, NOTION trial investigators reported a failure rate of 15.1% in the surgical arm, compared to 10.8% in the transcatheter arm, with no significant differences between the two groups overall, or for the individual endpoints apart from severe structural valve deterioration.
According to Abdel-Wahab, these findings lead to an important takeaway message from the trial: that TAVI valves perform at least as well as their surgical equivalents when it comes to durability.
“If you want to interpret the results in a more or less neutral way, we do not have any reason to believe that TAVI with the CoreValve device will have a durability issue compared to surgery,” he comments. “It is at least as good up to 10 years.”
Further, Abdel-Wahab notes that these results, while reflecting a positive long-term picture for the durability and outcomes with the CoreValve cannot be applied across all TAVI platforms. “It depends on several factors, but one key factor that affects durability is haemodynamics and we know from a lot of studies, this valve has the best in class haemodynamics, and it appears that this has an impact on durability,” he comments.
Also important to consider is that the NOTION trial results reflect experience using the first-generation CoreValve devices, which have now been replaced by the newer-generation Evolut™ (Medtronic) family of TAVI valves. Abdel-Wahab suggests that importantly as it relates to current practice, the design of the leaflets of the supra-annular device, which contributes to its durability, remain consistent between the earlier generation and the currently available devices. Changes between the generations have focused on the stent frame and the delivery of the device, which he suggests mean that durability is likely to be similar with the newer systems.
“Other endpoints may be favourably affected by the newer-generation device, because you have fewer acute complications with this device compared to the previous one,” Abdel-Wahab speculates. “You can position it more precisely for example, [and] you have fewer leaks or pacemakers. The delivery catheter is smaller so you may have less vascular and bleeding complications. All of these acute complications affect long-term outcome as well.”
Considering how these results will impact his practice, Abdel-Wahab says that his institution is already “progressive” in considering TAVI as a treatment option for patients considered at low risk for surgery, but the latest data help to focus discussion, particularly if more long-term data confirm the findings seen within NOTION. Importantly, he says, the trial can change thinking about the lifetime management of younger patients who may be considered for TAVI, and face the possibility of needing a further procedure later down the line.
“If you think that the patient will need a second valve then you need a plan, and you need to be sure that it will be anatomically possible. This is the way things should be discussed in the heart team,” he says, commenting that if a patient may be suitable for either TAVI or surgery, then the decision may be based on the possibility for reintervention later down the line.
Asked how future iterations of practice guidelines could take these results into account, Abdel-Wahab offers the view that a simple “age-based” recommendation for TAVI or SAVR may not be sufficient to identify the patients who are most suitable for either strategy.
“We are learning a lot on how to decide which strategy to use, and it should not be an age cut-off, but it should be an anatomical decision-making process for patients, based on the expected acute result and the expected possibilities for reintervention in the future,” he concludes.
The 10-year NOTION data add to the growing body of evidence to support decision-making when weighing up the best choices for treating aortic stenosis. This continues to evolve, with the release of four-year results from the Evolut Low Risk trial at TCT 2023 (23–26 October, San Francisco, USA; see cover story), and the first anticipated data release from the SMART post-market trial, a randomised, head-to-head study comparing the Evolut PRO and PRO+ systems with the Sapien 3 and Sapien 3 Ultra valves (Edwards Lifesciences), helping to guide physicians further.
