‘Signal’ of Poor Durability Seen With First-Generation TAVR Devices
PARIS, France—Among TAVR patients who survive to 5 years, up to half will see their devices begin to degenerate by 10 years after implantation, researchers reported today at EuroPCR.
While degenerated valves do not necessarily proceed to outright failure, the findings are a “signal” of a potential problem in a world where TAVR is being considered in increasingly younger and lower-risk patients, researcher Danny Dvir, MD (St. Paul's Hospital, Vancouver, Canada), said in a press briefing. “We know very little about the durability of TAVR procedures,” he cautioned.
Discussant A. Pieter Kappetein, MD, PhD (Erasmus University Medical Center, Rotterdam, the Netherlands), said after Dvir’s presentation that the findings will give TAVR critics the opportunity to say, “I told you so.” Whether that is justified is still uncertain, he commented. That being said, he added, there are lessons about durability to be learned from the surgical field, which has had its share of ill-fated devices.
Degeneration Takes Years to Appear
Dvir and colleagues looked at 704 patients (mean age 82 years) who underwent TAVR at St. Paul’s Hospital in Vancouver, Canada, and Hôpital Charles Nicolle in Rouen, France. Patients then were monitored using repeat echocardiographic exams during house visits for up to 10 years.
After excluding patients who died within 30 days of TAVR, had immediate device failure, were undergoing valve-in-valve procedures, or met other exclusion criteria, the final study population consisted of 378 patients. Valves included the Sapien (50%), Sapien XT (36%), and Cribier (14%), all balloon-expandable devices manufactured by Edwards Lifesciences.
Degeneration was defined as moderate/severe regurgitation and/or aortic stenosis (mean gradient > 20 mm Hg) that was not apparent within 30 days of the initial TAVR and was not related to endocarditis.
“It’s not failure, it’s degeneration,” Dvir stressed, estimating that approximately 40% of degenerated valves would eventually fail.
Of the 100 patients who survived at least 5 years after their procedure, 35 showed signs of valve degeneration (66% regurgitation and 33% stenosis/mixed). Median time to degeneration was 61 months. “So we need a lot of follow-up time in order to see many of these failures,” Dvir noted.
On Kaplan-Meier analysis, the curve for freedom from degeneration drops from 94% at 4 years to 82% at 6 years and to approximately 50% at 8 years among surviving patients.
The findings should not be extrapolated beyond the first-generation TAVR devices studied here, Dvir stressed. “This is a very early report. We need to be very cautious. It’s a very small number of cases [and] the first look at these data.”
Much like has been seen with surgical valves, renal failure was the strongest correlate of transcatheter valve degeneration, he reported.
This “phenomenon” of valve degeneration, Dvir said, was not immediately apparent in the early days of the field, particularly since patient survival was in the range of 3 years following successful TAVR. “But now they survive [longer], because we’re doing it in lower-risk patients. We need to understand that when we target younger patients, lower-risk patients who will survive longer, they may fail with their [TAVR] device.” Clinicians also should be mindful of which valve they choose to implant, with the idea that a valve-in-valve procedure may one day be needed, he advised.
To further explore this issue of long-term durability, Dvir and colleagues are initiating the VALID registry.
‘Gradual, Natural Phenomenon’
Until the valve actually fails, “usually we do not expect to see symptoms,” Dvir acknowledged. But based on his long-term experience doing valve-in-valve cases, he observed that “it’s not always easy to understand if the valve has truly failed or just is significantly degenerated.”
Degeneration, while perhaps not as easily quantifiable, is more informative than the reintervention rate, Dvir noted. “These are 90-something-year-old people, very old, and many of them were treated palliatively. It’s not a group of patients you’re very keen to do an intervention on. So the rate of reintervention is very low.”
Asked whether a different anticoagulation strategy might prove helpful, given the calcification that was seen on some valves, or if increasing duration or intensity of anticoagulation would be too risky, Dvir replied: “That is a very good question,” but one that does not currently have an answer.
One clue, though, is that renal failure was far and away the strongest factor associated with degeneration, while there was no such link with anticoagulant treatment, he said. Moreover, “in the stenosis group, these were not acute cases. They had low gradients and . . . after a couple of years there was a gradual jump in the gradient and a decrease in the [effective orifice area]. It makes me think that this is a gradual, natural phenomenon of an [interaction] between the body and the valve.”
According to Dvir, there is no easy way to compare the current findings with degeneration that might occur with surgical valves. “I can say that most of the surgical failure or degeneration studies looked at reinterventions,” and thus would be hard to apply to this elderly TAVR population, he noted. Pressed to answer whether degeneration happens faster in percutaneous versus surgical valves, Dvir was cautious, saying: “There is a signal for a problem, but [the study was] not designed to do a real comparison between surgery and TAVR.”
Nor is there anything to suggest that newer-generation valves have qualities that would prevent or delay degeneration—this is information that will require another 3 to 5 years. He did note, however, that Sapien 3 (Edwards Lifesciences) is associated with less paravalvular leak than its predecessors and as such may be less prone to degeneration.
Justification for Trials
In his remarks following Dvir’s presentation, Kappetein noted that the findings in TAVR are not without precedent.
Numerous surgical valves have been sold over the years, and some have been duds, starting to fail at 8 to 10 years, he commented. As is the case with surgical valves, many factors—from the means of delivery to the way the device is anchored and the ability of its frame to face challenges over time—“play a role in valve durability,” he explained. “All of these have to be addressed to be able to provide durability is long enough [that] the patient can live with the valve.”
Previous research has shown that after valve surgery, there is more deterioration in younger versus older patients, Kappetein reported. “So I think we have to be careful before we move towards lower-risk patients with transcatheter heart valves. Somehow we can say it’s not unexpected. [Yet while the durability question] didn’t play a major role in [octogenarians], it will play a role in younger patients.”
It’s possible that newer-generation valves may fare better, he agreed. “But it points us to the fact that trials in lower-risk patients are justified. We cannot just start implanting those valves in lower-risk patients.”
- Dvir D. First look at long-term durability of transcatheter heart valves: assessment of valve function up to 10 years after implantation. Presented at: EuroPCR 2016. May 17, 2016. Paris, France.
- Dvir reports consulting for Edwards Life Sciences, Medtronic, and St Jude.
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