DURHAM, NC — Transcatheter heart valves have a shorter track record than that of surgically implanted bioprosthetic valves, but a new study suggests that aortic valves delivered via catheter may be in it for the long haul[1].
An analysis of core laboratory data from the PARTNER 1 trial showed that in the first few months following transcatheter aortic-valve replacement (TAVR) with the first-generation Sapien valve (Edwards Lifesciences), recipients had improved flow and other favorable hemodynamic changes and that the valves and the improvements associated with them appeared to be stable at a median of about 3 years of follow-up, out to a maximum of 5 years.
Rates of reintervention and serious complications were low both in patients receiving TAVR and in those assigned to receive surgical aortic-valve replacement (SAVR), reported investigators led by Dr Pamela S Douglas (Duke University Medical Center, Durham NC).
“This large, core laboratory evaluation of 2482 patients receiving TAVR and 313 receiving SAVR in the PARTNER 1 trial demonstrates excellent longitudinal durability of the Sapien [transcatheter heart valve] using both population hemodynamic trends as well as case reviews of reintervention and patients with large adverse changes between echocardiograms,” they write in the report, published September 27, 2017 in JAMA Cardiology.
“Abnormal findings in individual patients suggestive of valve thrombosis or structural deterioration were rare in this protocol-driven database and require further investigation.”
Nothing Lasts Forever
“I would expect that TAVRs, just like the bioprosthetic surgical devices, will have a finite lifespan,” Douglas told theheart.org | Medscape Cardiology. “It would only be a guess that the trajectory of that is going to be similar to the surgical valves out to 5 years.”
Evidence from clinical databases suggests that SAVRs begin to exhibit significant signs of deterioration 8 to 10 years after implantation, and it’s reasonable to suspect that TAVRs may have a similar or perhaps somewhat shorter shelf life, but they could prove to be more durable—only time will tell, she said.
In an accompanying editorial[2], Drs Stephen H Little and Michael J Reardon (Houston Methodist Hospital, Texas) noted that while the data thus far look good, it’s too early to say whether the relatively short-term durability seen in the analysis will continue as time goes by.
“Although the study by Douglas et al is encouraging and reassuring, it must be considered only a starting point and not a definitive answer. In this elderly group of patients, it is unlikely that we will see [structural valve deterioration] SVD in TAVR valves if they behave similarly to surgical valves because death will compete with SVD in this high-risk population,” they write.
Although PARTNER 1 was conducted in a high-risk elderly population, TAVRs will increasingly be used in younger patients with lower levels of risk, and for these patients the question of valve durability will be even more important, Reardon said in an interview.
“In the people we’ve tested TAVR in so far, it’s no real surprise that we haven’t seen much in the way of structural valve deterioration, because we wouldn’t expect it in surgical valves either to any extent, because the rate of developing structural valve deterioration is inversely related to the age of the patient when we put the valve in,” he said.
The study by Douglas et al “provides very valuable data, because what it tells us is that in the patient populations that we’ve tested so far, the interim analysis looks good, and so that’s helpful,” Reardon said.
In their editorial, Reardon and Little applauded the sponsors of two trials of TAVR in intermediate-risk patients, PARTNER 2 and SURTAVI trials, and two trials in low-risk patients, PARTNER 3 and Evolut Low Risk, for committing to a minimum of 10 years of follow-up.
Hemodynamic Trends
Douglas and colleagues looked at ECG data generated by the single core laboratory designated in the PARTNER trial from all patients enrolled who had successful TAVR with the Sapien valve or SAVR. For comparison purposes, they also looked at data on patients in continued-access observational studies.
The mean patient age was 84.5 years, and 47% of patients were female. As reported previously by theheart.org | Medscape Cardiology, a secondary analysis of PARTNER data showed that women are more likely than men to be alive 1 year after TAVR despite more vascular complications and major bleeding at 30 days.
The investigators used nonlinear mixed-effects models to study hemodynamic trends. They found that in the overall TAVR population of 2482 patients, there were small favorable changes in the first few months after valve implantation, including a reduction in aortic-valve mean pressure gradient from 12.1 to 9.2 mm Hg, which then increased slightly to 10.1 mm Hg at 5 years.
There were similar improvements in Doppler velocity index (increase of 0.028 m/s) and in effective orifice area (increase of 0.09 cm2).
Moderate transvalvular aortic regurgitation occurred in 89 patients (3.6%) in the TAVR cohort, and six patients in this group had severe regurgitation on at least one ECG during the trial. There were two cases of moderate aortic regurgitation but no severe regurgitation among patients in the SAVR cohort.
In the TAVR group, death or reintervention for aortic-valve structural indications, one of the primary end points, was found to be associated with lower ejection fraction, stroke volume index, and aortic valve mean gradient pressure up to 3 years after implantation. There was no association of this end point with either Doppler velocity index or effective orifice area.
A total of 20 patients in the TAVR group (0.8%) and one in the SAVR group (0.3%) required reintervention, primarily for paravalvular leak. Of the TAVR patients requiring a second intervention, five had structural indications, including one case of aortic stenosis, one case of valve thrombosis, and three cases of transvalvular aortic regurgitation.
“Severely abnormal hemodynamics on echocardiograms were also infrequent and not associated with excess death or reintervention for either TAVR or SAVR,” the investigators wrote.
Voting With Their Feet
Reardon told theheart.org | Medscape Cardiology that TAVR is increasingly being used in younger patients and that many of his patients have expressed a preference for the less invasive procedure.
“But as you move down the risk pattern, you really should say to yourself, if I’m going to use this as a surgical valve, it should show at least equivalent mortality, it should show at least equivalent hemodynamic function of the valve, it should show at least equivalent improvement in quality of life, it should show at least equivalent patient acceptance, it should show at least equivalent morbidity, and it should show at least equivalent durability,” he said.
“I would predict that the mortality in low-risk [patients] will be just as good with TAVR. It will be noninferior. It’s going to be hard to be superior, because surgical results are already so good,” he added.
The study was funded by Edwards Lifesciences. Douglas leads the PARTNER 1 echocardiography core laboratory. Disclosures for the coauthors are listed in the paper. Little has received grants from Medtronic and Abbott. Reardon serves on the advisory board for Medtronic.
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