TAVI (Transcatheter Aortic Valve Implantation) has firmly established itself as a mainstream treatment for aortic stenosis. This is due to its short procedure time, minimal discomfort, and proven long-term safety, thanks to diligent efforts by medical professionals. Moreover, the expansion of TAVI procedures in Korea, supported by increasing insurance benefits, albeit still limited, is anticipated.

While TAVI has shown proven effectiveness and safety, like all medical treatments, it cannot be guaranteed to be "100 percent safe." Many high-risk patients undergo TAVI, so the notion that "procedure equals success" does not always apply.

Nonetheless, Hanyang University Medical Center's (HYUMC) cardiovascular team has taken on the challenge of advancing TAVI procedures.

Since 2022, HYUMC has performed TAVI procedures by forming a multidisciplinary cardiovascular team led by four Department of Cardiology professors -- Kook Hyung-don, Lim Young-hyo, Kim Woo-hyun, and Heo Ran. Notably, they have recorded zero in-hospital mortality for TAVI procedures to date. Korea Biomedical Review caught up with Professor Kook to learn about the latest advances and know-how in TAVI procedures.

Professor Kook is an expert in cardiovascular and structural heart disease interventional procedures, including aortic valve stenosis, aortic disease, and percutaneous aortic valve replacement. He is the youngest proctor of the three major TAVI companies -- Boston Scientific, Edwards Lifesciences, and Medtronic – that have been introduced to Korea.

Question: What are current trends in TAVI procedures?

Answer: Globally, TAVI procedures are increasingly performed in younger and lower-risk patients. The TAVI procedure first emerged as an alternative treatment for patients who were not candidates for open-heart surgery. Over the 21 and 22 years that TAVI has been available, there have been many studies comparing surgery and TAVI, and they have consistently shown better or equal outcomes with TAVI compared to surgery.

More and more people are now being treated with TAVI instead of surgery, and guidelines in the U.S. and Europe are relaxing their criteria for recommending TAVI. As a result, TAVI is being performed in younger, lower-risk patients (than those currently eligible for the procedure). In Korea, the number of patients undergoing TAVI has increased significantly over the past few years as reimbursement standards were relaxed.

Q: In 2022, TAVI procedures received insurance benefits. What was the difference after the shift to reimbursement?

A: Previously, patients had to pay upwards of 30 million won ($21,747) to have TAVI, which meant that many patients who knew they would benefit from TAVI could not pursue it because of the cost. But this hurdle seems to have been overcome, especially for older adults.

Q: What sets HYUMC’s cardiovascular team apart from others in TAVI procedures?

A: We are not a large center. Instead, we specialize in high-risk, complex procedures. In some cases, such as patients over 90, the femoral artery is in poor condition due to aging. In these cases, TAVI may have to be abandoned. However, we have had successes with TAVI through the carotid artery in patients in their 90s. The average age of our patients is between 85 and 90, so we have a very high-risk, elderly patient population. We're doing very well in those patients, and that's one of our strengths.

Besides, we boast zero in-hospital mortality. Without proper treatment, more than 60 to 70 percent of patients with symptomatic severe aortic valve stenosis who are candidates for TAVI usually die within two to three years. There is no way to improve survival with medication, so the only way to treat the disease is to replace the valve, which has its risks. Globally, there is a 2-3 percent chance of death after the procedure but we have no in-hospital mortality. We have zero in-hospital mortality despite doing high-risk, complex procedures.

The reason we have such a good process is not because I am good but because the teamwork of the cardiovascular team is excellent.

Q: Any memorable anecdote?

A: I had a 93-year-old patient who was hospitalized with a femur fracture. When we were checking his heart and lung function to see if he could go under general anesthesia before the femur fracture surgery, we discovered that he had aortic stenosis. Severe aortic stenosis can cause the heart to suddenly stop functioning during general anesthesia, making it difficult to perform femoral fracture surgery.

After consulting with the orthopedic surgeon, we decided to perform the TAVI procedure first and then perform the femur fracture surgery about a week later. However, during the pre-TAVI examination, we found that the blood vessels in his legs were completely blocked on both sides. This is a difficult situation for TAVI, so we decided to perform the TAVI procedure through the carotid artery.

After TAVI, many patients feel strongly that their quality of life has improved, and talk about the changes they've noticed. I've even had patients brag about playing golf well into their 90s after TAVI. It's rewarding to hear patients talk about how their lives have changed after TAVI.

Q: We are curious to see how the TAVI procedure will evolve.

A: Currently, worldwide, patients must have severe aortic stenosis to be eligible for TAVI. The risks of TAVI are significantly less than those of surgical treatment. With the improved understanding of TAVI and the technical advances and skills of the TAVI technicians, studies show that patients with asymptomatic, pre-severe aortic stenosis may benefit from TAVI.

It is hoped that TAVI can replace other valves, not just the aortic valve. As our understanding of the anatomy improves and the device technology improves, it may become possible to perform the procedure in patients who do not necessarily have aortic valve stenosis.

For instance, I have heard that TAVI devices are developed to treat aortic regurgitation where the aortic valve fails to close. The time will come when TAVI can treat not only stenosis but also regurgitation.

Q: We heard that you are the youngest proctor in Korea to be qualified to supervise the three major companies’ TAVI medical devices. That means you must have a good grasp of the characteristics of each product.

A: In Korea, there are four devices available for TAVI procedures. The fourth device (excluding those of Boston Scientific, Medtronic, and Edwards Lifesciences) was introduced in Korea earlier this year. We haven't had much experience using it yet.

Of the other three devices, one is “balloon-expandable,” while the other two are “self-expandable.” Among them, a relatively new valve made by Boston Scientific (“ACCURATE neo2” released in 2022) is characterized by that it unfolds from the middle, which is better for maintaining the axis of the valve, and has fewer problems with interference with the heart vessels or interference with the heart's electrical conduction.

Q: As the youngest supervisor of TAVI medical devices in Korea, what are your aspirations?

A: That’s one of the most difficult questions. I am the youngest doctor performing TAVI procedures in Korea not because I am outstanding, but because my mentor (Professor Yu Cheol-woong of Korea University Anam Hospital) gave me the opportunity early. He opened the door for me to pioneer the TAVI procedure from an early age, so I feel like I'm getting a lot of opportunities.

I want to maintain zero in-hospital mortality in TAVI procedures at HYUMC, which may sound arrogant and hype because of the risks of this procedure. Still, I want to maintain zero in-hospital mortality.

The second wish is to make our center a “structural heart disease” center, where we address structural problems of the heart, including TAVI. The long-term goal is to make ours a center that performs complex procedures that are difficult for other hospitals to perform.

Q: When you say you want to become a specialized structural heart disease center, does that mean you want to expand beyond TAVI procedures?

A: Exactly. We want to expand the horizons of treating structural heart diseases, such as valvular regurgitation and atrial fibrillation. Ultimately, the hope is that we will do only TAVI procedures. Unlike Canada and other developed countries in Europe, we don't have interventionalists who do only valve procedures. In Korea, one does heart valves, one does cardiac vascular procedures, and one person does leg vascular procedures if necessary.

However, one must have a subspecialty in subdivided fields to become a global specialist and make further advancements. So, I hope they create an environment where I can focus on TAVI procedures, the theme of my life, among the many fields of cardiology. Of course, it will not happen with my efforts alone but various circumstances should be right.