“From now on, Korean hospitals should provide Transcatheter Aortic Valve Implantation (TAVI) procedures tailored for patients.”
Professor Kim Hyo-soo of the Cardiology Department at the Seoul National University Hospital (SNUH) said so during an interview with Korea Biomedical Review on July 9.
TAVI is an emerging treatment for aortic valve stenosis.
TAVI is a non-surgical method of replacing the aortic valve without opening the chest, offering low risk of postoperative complications, and helping patients recover in a short time. The number of TAVI procedures has significantly increased after the nation introduced it eight years ago.
The SNUH has performed over 300 TAVI procedures, and major university hospitals such as Asan Medical Center and Seoul St. Mary’s Hospital, over 100, respectively.
Physicians are using TAVI as a major therapy for aortic valve stenosis.
Recently, researchers published study results saying TAVI was safe and effective not only for patients with high and moderate surgical risk but for the low-risk group. The U.S. Food and Drug Administration has granted TAVI to treat low-risk patients, and the latest nod is expected to make TAVI more popular.
However, some question TAVI’s long-term therapeutic effect because TAVI's history is shorter than Surgical Aortic Valve Replacement (SAVR). Controversies over who can receive TAVI procedures and whether to increase the out-of-the-pocket payment persist.
Korea Biomedical Review met Kim, a former chairman of the Korean Society of Interventional Cardiology, to learn the status of TAVI procedures, controversies, and why he supported customized TAVI.
|Professor Kim Hyo-soo of the Cardiology Department at the Seoul National University Hospital speaks during an interview with Korea Biomedical Review at the hospital on July 9.|
Question: What is the latest domestic trend of the TAVI procedure?
Answer: TAVI procedures in Korea are certainly increasing. About 700-800 patients have already received TAVI this year. But the local increase is gradual, not explosive, as seen in overseas cases. Some attribute the slow growth to economic reasons. Many domestic patients with aortic valve stenosis hope to get TAVI, but they have to pay 80 percent of the cost. So, due to the financial burden, they get SAVR instead. In contrast, the Japanese government supports the cost of TAVI for super-aged patients. Thus, the number of TAVI cases is high in Japan.
However, I don’t believe that a state-funded TAVI procedure is reasonable socio-economically. We need to think if it is right to give a super-aged patient over 90 a free TAVI procedure with the state insurance spending. As aortic stenosis patients have another option, surgery, it is better to provide selective reimbursement so that patients who need or want TAVI can get the procedure. Selective reimbursement helps save the state spending on the national health insurance.
Q: Some patients cannot afford TAVI. What should we do for them?
A: If the proportion of TAVI insurance benefits increases, the accessibility of patients in need may be limited. This is because, if TAVI wins full reimbursement, physicians cannot perform the procedure outside the reimbursement standard. If TAVI benefits increase, SAVR procedures will go down. Then, surgeons may protest it. The government will worry that a significant rise in TAVI procedures will lead to more health insurance spending. So, the government may limit TAVI to only those highly likely to die if treated with SAVR. In other words, TAVI may be possible only for patients with not much left to live. This should not happen. Increased reimbursement for TAVI may cause “moral hazard.”
Some patients may ask doctors to manipulate their disease scores to get TAVI insurance benefits. Doctors may turn a blind eye to this problem to increase TAVI procedures to make more profits. All kinds of side effects can occur. So, it is appropriate to allow selective reimbursement for TAVI, saving the state money on health insurance and giving patients more treatment options.
Q: It sounds as if TAVI is superior to SAVR, and many doctors and patients prefer TAVI to SAVR. Do you agree?
A: Study results showed that TAVI was superior to surgery or at least equal to surgery in all high risk, moderate risk, and low-risk patients with aortic valve stenosis. But some argue that surgery may be more beneficial in the long term. This is why it is difficult to conclude, which is more superior.
What’s certain is that many patients prefer TAVI because it is simple, causes fewer side effects before and after the procedure, and produces lower death and stroke incidence rate in the two-year follow-up. But TAVI is expensive. If TAVI fails, or valve aged after TAVI, the patient requires a skillful surgical procedure. So, we should maintain a price discrimination policy and let the surgery system stay.
Q: A recent study said TAVI was effective in low-risk aortic valve stenosis. Will this expand the scope of patients who can receive TAVI?
A: The controversy over whether to apply the TAVI procedure according to the patient's risk group has ended with many research results. It is more appropriate to determine whether or not to apply TAVI based on the patient's age and the valve. The European guidelines recommend that TAVI be used to patients older than 75 years of age. This is because the patient's weakened physical strength raises the burden of chest incision surgery. Surgeons are still not very experienced with TAVI, so we expect the procedure to work for about 10 years. If the patient is about 75 years old, there will be no difficulty living for 10 years after TAVI.
Q: Can you comment on concerns about side effects after a TAVI procedure, such as leakage around the valve?
A: Minor side effects can occur depending on the surgeon. It is also essential to know which patient needs which artificial valve. There are three types of artificial valves – Sapien 3 by Edwards Lifesciences, Evolut R/PRO by Medtronic, and Lotus Edge by Boston Scientific -- used in TAVI procedures in Korea. These valves have different mechanisms and characteristics, so surgeons should choose accordingly.
Q: What are the characteristics of the three artificial valves?
A: Evolut has the advantage of self-expansion and safe operation. However, because the artificial valve expands in the blood vessel instantly during the procedure, there is a higher possibility of paravalvular leakage (PVL) than other products. This valve has a chance of atrioventricular blockage. So, if the electrocardiogram test shows an atrioventricular disorder or there is a lot of calcium around the valve, surgeons don’t use it.
Sapien 3 can treat patients with low PVL concerns and those with very thin blood vessels, but surgeons should be careful if the patient’s blood vessels are weak.
Lotus Edge has the advantages of the other two products. In addition to self-expansion, the frame is compact, so there is less concern for PVL. As the device has a “recapture” function, it can be used for patients with anatomical limitations, such as those with the bicuspid aortic valve. However, the procedure with Lotus Edge is somewhat more difficult than those with the previous two products.
Q: How do you select artificial valves depending on patients?
A: If a patient is over 90 years old, the blood vessels must be very weak. In this case, it is more important to secure the procedure's safety than to address the risk of valve leakage. So, I would consider using Evolut. Surgeons should consider various patient traits, including atrioventricular conduction blocking, blood leakage, aging degree, blood vessel thickness, and tissue strength, whether the patient has coronary artery disease, life expectancy, and heart structure. Surgeons should be able to use all three types of valves. But in Korea, the SNUH is the only hospital that provides TAVI with all the three types of artificial valves.
Q: Physicians must prefer an artificial valve that they feel comfortable with, and that is easy to use during the procedure, right?
A: Yes. Doctors prefer the artificial valve they used for the first time, but they should consider patients' various situations. For years, only two types of artificial valves, Evolut and Sapien 3, have been used in clinical settings, and many patients have benefited from TAVI procedures using the two. However, for patients with a bicuspid aortic valve, we needed a better option. This is because Evolut and Sapien 3 could cause PVL in patients with a bicuspid aortic valve.
Q: How do you think TAVI procedures will change?
A: TAVI-related technologies continue to advance, and physicians build up experiences. In the future, physicians will perform TAVI first and additional surgery on those who fail in TAVI. The age available for TAVI will also go down. To keep up with the trend, surgeons need to raise the quality of TAVI. The SNUH’s TAVI team is making an index on valve leakage. The index, soon to be published, will help improve Korean TAVI procedures. Also, TAVI procedures will get customized for patients. Recently, SNUH’s TAVI procedures exceeded 300 cases. The hospital conducted the standard medical checkup for each patient and used the most appropriate artificial valve for each.