TAVI Matches SAVR in Older US Patients With Rheumatic Aortic Stenosis
Although the observational results are promising, durability could be a concern in patients decades younger.
For people who have aortic stenosis (AS) due to rheumatic heart disease (RHD), transcatheter valve implantation may be a “viable and possibly durable option” compared with surgical valve replacement, observational Medicare data suggest. The study found no difference in all-cause mortality over a median follow-up period of around 1.5 years.
While RHD is on the decline in affluent countries, it still leads to more than 300,000 deaths each year worldwide. In Africa alone, an estimated 15 million people have RHD.
Yet little is known about TAVI in patients with RHD, because they were excluded from the US and European pivotal trials, which enrolled people with degenerative calcific AS. When AS occurs in patients who have RHD, on the other hand, the aortic valves “usually exhibit significant fibrosis, with calcification only occurring late in the degenerative process,” researchers led by Amgad Mentias, MD (Cleveland Clinic Foundation, OH), point out in their paper, which was published online today in the Journal of the American College of Cardiology. These anatomical differences could negatively affect transcatheter device deployment and anchoring.
Mentias stressed to TCTMD that there’s a large clinical need. “In Egypt,” where he’s originally from, “we have a lot of rheumatic heart disease, and I remember my earlier training when I used to see a lot of [patients] who came late in their course when heart failure had already happened and myocardial damage had already happened. And they would be declined surgical intervention just because it’s a high-risk procedure.”
What the new study results show, he said, is that in select RHD patients being treated in the United States, TAVR “was relatively comparable to surgical aortic valve replacement in terms of midterm outcomes.” Beyond the equivalent death risk, another noteworthy finding is that none of the TAVI-treated RHD patients required reintervention.
The takeaway, Mentias said, is “cautious optimism.”
Of note, there are differences between how RHD manifests in the United States versus in low- and middle-income countries, where these potential TAVI candidates would be decades younger than those included in the Medicare data set, Peter Zilla, MD, PhD (University of Cape Town and Groote Schuur Hospital, South Africa), and colleagues stress in an accompanying editorial.
This doesn’t mean the results aren’t valuable, Zilla et al say. “Although patients with RHD living in North America are nonrepresentative of the millions of patients living with the disease in less-privileged parts of the world, a study like this must be commended for opening a door,” they write.
What’s missing now are long-term data. “We don’t know whether this will hold in years to come,” said Mentias, who also highlighted the wide age gap between the US patients and those in lower-income countries. “However, it is an encouraging signal that should encourage people to do randomized controlled trials between TAVR and SAVR in patients with rheumatic heart disease.”
All-Cause Mortality Similar
Using ICD-10 diagnosis codes, Mentias et al identified 1,159 Medicare beneficiaries with rheumatic AS, of whom 48% underwent SAVR and 52% TAVI. They also included 88,554 patients with nonrheumatic AS who underwent TAVI. The interventions occurred between October 2014 and December 2017.
Among the patients with RHD, those who had SAVR tended to be younger than those who had TAVI (mean 73.4 vs 79.4 years), to have fewer comorbidities, and to be less frail. At a median follow-up of 19 months, all-cause mortality was similar between TAVI and SAVR (11.2 vs 7.0 deaths per 100 person-years; adjusted HR 1.53; 95% CI 0.84-2.79). Apart from permanent pacemaker implantation, TAVI was associated with fewer complications than SAVR.
Among the TAVI-treated patients, those who had RHD tended to be younger than those with nonrheumatic AS (mean age 79.4 vs 81.2 years), were less likely to be men (40% vs 53.3%), and tended to have fewer comorbidities. At a median follow-up of 17 months, all-cause mortality did not differ between TAVI patients who did and didn’t have RHD (15.2 vs 17.7 deaths per 100 person-years; adjusted HR 0.87; 95% CI 0.68-1.09). There were no differences in procedural complications.
Repeat aortic valve replacement was performed in one of the TAVI-treated patients with rheumatic AS, fewer than 11 SAVR patients with rheumatic AS, and 242 nonrheumatic TAVI patients.
Why RHD Poses Challenges
Mentias et al acknowledge there have been concerns in the past about performing TAVI in rheumatic AS because of the lack of calcification, used for anchoring, in the native valve, which could potentially lead to prosthetic valve migration or paravalvular leak. New-generation TAVR devices have design elements that could reduce the likelihood of these problems, however. “Our study included a contemporary cohort of TAVR patients; hence, it reflects outcomes with newer generations of TAVR valves.”
Also, many patients with RHD have aortic regurgitation, either on its own or in combination with AS. For these patients, the lack of calcification may enable “safer deployment with appropriate oversizing to reduce the risk of residual paravalvular leakage without increased risk of annular injury/rupture as compared with calcific AS,” the researchers say, “especially in patients with concomitant/pure aortic regurgitation and dilated aortic root.”
A final challenge, they add, is that “patients with RHD also tend to have concomitant disease of multiple valves; hence, it makes the clinical correlation of patients’ symptoms to a specific valve malfunction challenging.”
Further insights into how TAVR could perform in this setting must be explored in parts of the world where rheumatic aortic stenosis predominates, the authors say. “In developing countries, despite lack of such information, one must assume that a large proportion of those with AS is due to RHD. The differential criteria on echocardiogram as well as lack of severe calcification can confirm such a theory in large cross-sectional cohorts.
“Introducing TAVR for rheumatic AS in these countries can offer a good alternative to surgical valves,” they continue, “especially in areas with low surgical capacity or for patients with concerns over lack of adequate anticoagulation monitoring with mechanical valves. On the other hand, the durability of TAVR valves must be adequately studied before widespread use in this relatively younger population.”
Asked about cost, Mentias replied that the price of the devices has dropped over the years. “And TAVR is already being done in some low-to-middle-income countries like India and Egypt,” he pointed out, adding, “When you count the short-term care that the SAVR patients require, actually the cost [for that] is high—it’s not low.”
The editorialists call for caution, outlining the striking evolution of aortic valve replacement over time in high-income countries, where they say device technologies have targeted an elderly population and stagnated when it comes to the needs of patients younger than 40 years. “With more than 98% of TAVR patients older than 60 years, tissue degeneration is very slow, and the longevity of the valve largely exceeds the patient’s life expectancy,” they explain; thus, there was no urgency to improve durability.
Beyond the need for durability, device design is key for patients with RHD, who are “at least 30 years younger than the 79-year-old TAVR recipients reported in this study,” Zilla et al stress. “For them, mortality is less determined by preexisting comorbidities and old age than by ventricular dimensions at the time of the operation (patients are often seen for the first time past the point of operability) and by the choice of prosthesis.”
The findings of Mentias and colleagues “will hopefully act as a catalyst of higher awareness for the ‘many’ and, crucially, for industry to see in the huge underserved population of emerging economies an incentive to develop heart valve prostheses that also cater to these patients,” they conclude.
As to next steps, Mentias observed that it would be hard to get sufficient numbers of RHD patients for a randomized controlled trial in the US or Europe. To do a well-conducted RCT in low- and middle-income countries will require collaboration between industry and cardiology leaders and societies in these regions, so that researchers have access to the necessary expertise and support. “That will give you a real answer about feasibility and durability in such populations,” he said.
Mentias A, Saad M, Desai MY, et al. Transcatheter versus surgical aortic valve replacement in patients with rheumatic aortic stenosis. J Am Coll Cardiol. 2021;77:1703-1713.
Zilla P, Williams DF, Bezuidenhout D. TAVR for patients with rheumatic heart disease: opening the door for the many? J Am Coll Cardiol. 2021;77:1714-1716.
- Mentias received support from National Institute of Health NRSA institutional grant to the Abboud Cardiovascular Research Center.
- The editorialists report no relevant conflicts of interest.