With recent data pointing to a shift towards more transcatheter aortic valve implantation (TAVI) procedures taking place across the USA, overtaking surgical aortic valve replacement (SAVR) for the first time in 2019, Cardiovascular News spoke to Joseph Bavaria, vice chief of the division of cardiovascular surgery, University of Pennsylvania, Philadelphia, USA, a former president of the Society of Thoracic Surgeons (STS) and recent chair of the STS/ACC TVT Registry, the US national TAVI database, to discuss the future of TAVI and SAVR.
What is your expectation for future trends in TAVI and SAVR?
TAVI is increasing dramatically. This tends to happen in fits depending on the data that come out in the prospective randomised trials regarding risk profiles. For example, when the first data on TAVI in high-risk patients came out it [TAVI] went straight up and then it plateaued a little bit, as the high-risk cases were absorbed. Then, the intermediate risk data came out, the acceleration went up, the slope of the curve went up, and it started to flatten again, and in low-risk patients it is actually in the acceleration phase right now.
My expectation is that the low-risk prospective randomised trial data will make its way through the community over the next 24 months, so the number of TAVI cases will go up, and then it will start to plateau a little bit, with a more organic level of growth—maybe 6% per year, instead of 30% growth per year. The TAVI growth will be steady and impressive over the next 24 months as low risk TAVI concepts are absorbed by the community.
What have we learned from the latest studies on TAVI in low-risk patients?
The data from the low-risk trials may indicate a “crossing” of the outcomes at two to three years. The two-year PARTNER 3 data was slightly worrisome in the sense that surgery was steady, but the TAVI outcomes were getting worse. The curves were coming together, and if they stay like that they will end up crossing, which would mean that surgery will actually end up being better at three to five years. That data is going to be very powerful, regarding adoption of TAVI into low risk patients.
It is very interesting on that score, to understand that the new ACC/AHA guidelines for aortic valve disease, which came out in early December, were not 100% favourable for low-risk TAVI. The guidelines walk the fine line between too much and too little. They made a very specific point of recommending that if you are under 65 years of age TAVI is not indicated. The guidelines are still a little bit of a moving target.
What can we expect to see in terms of trends in SAVR procedures?
Surgical aortic valve procedures are segmented into isolated aortic valve replacement, aortic valve replacement with coronary bypass surgery (AVR-CABG), AVR/Other, and Bentall procedures.
Isolated AVR has come down about one-third over the past three or four years. AVR-CABG has also come down a little bit, around 10%. That is because people are getting TAVI with percutaneous coronary intervention (PCI)—two sequential endocardiac procedures. On the other hand, the AVR/Other category—which includes aortic valve replacement with an ascending aorta, aortic valve with an electrophysiological procedure, aortic valve replacement with a mitral valve, etc.—is either flat or actually slightly up. That is not going away. TAVI does not address these problems, it is not sophisticated enough to address complex cardiac structural issues, whereas surgery can correct three problems at the same time. One cannot really accomplish that with isolated TAVI.
Fourthly, Bentall, which is an aortic root procedure, are up about 12—18% per year for the last five years, according to the STS National Database.
Stepping back, surgical AVR as a whole is coming down slightly, when you add up all four of those categories and you can even add a fifth—aortic valve repair—what you see is that TAVI outnumbered isolated AVR back in 2016, but TAVI did total more than the entire universe of AVR until 2019.
Right now we have more TAVI in the USA than the whole AVR universe. But, the surgical AVR universe is flat, it is going down with isolated AVR, and even a little bit down with AVR-CABG, [and] it is going up with AVR/Other cases and Bentall procedures. So, it is a very interesting subset. Aortic valve replacement surgery is not going away, but it is not really growing either, as a whole.
What is your advice to heart teams about how to best navigate the choice of TAVI or SAVR?
When you have something that is complex, the heart team is really important because you have different perspectives and knowledge bases on all of the components of the best treatment plan. It is not really an either/or question, sometimes it is that a particular patient will have a multitude of issues, and maybe the team needs to go one way or the other.
The heart teams have to know the data. The data is changing every day a little bit. TAVI is not a totally mature therapy yet and so the heart team is really important to navigate all of those questions, for example, if you have a bicuspid valve patient—they should probably go to surgery, because the results of surgery are excellent. But, if it is an 80+ year old, maybe you want to try TAVI, even though it is not quite as established as a treatment in a bicuspid valve patient.
If the patient has coronary disease, the team will have to weigh whether they want to do an AVR-CABG, which may be more definitive than a TAVI with a PCI, and realise that a PCI after TAVI is more complicated.
What developments should we expect in the coming years in terms of TAVI devices and techniques?
The problem for the companies regarding TAVI now is that the new generation technology has to be good because the bar is already high. I think we will still see more incremental improvements as time goes on—it might be more iterative these days, as opposed to dramatic.
The two biggest disappointments regarding TAVI in the last six years or so, are that we have not improved our stroke rates or our pacemaker rates over that timeframe. This is despite having better valves, and despite going into lower-risk patients. This is a problem that has been clearly documented by the big data from the STS/ACC TVT Registry.
These are the areas that any new technology has to address. We have improved at everything else over the past decade.
Transcatheter mitral and tricuspid procedures are coming along very strong, and a really satisfactory and effective transcatheter mitral valve replacement would be revolutionary.