Clinical Innovators: Pioneering Novel Treatment for Heart Valve Disease | Interview by Katlyn Nemani, MD
CardioSource WorldNews | Internationally known for his expertise in novel percutaneous and transcatheter approaches to heart valve disease, D. Scott Lim, MD, currently serves as the medical director of the Advanced Cardiac Valve Center at the University of Virginia. He specializes both in the elderly and in children with acquired and congenital heart valve disease. Dr. Lim created and continues to run a humanitarian charity endeavor between UVA and Cedimat Hospital in Santo Domingo, Dominican Republic, for the care of patients with rheumatic heart valve disease, as well as for the education of Dominican physicians who care for them. Dr. Lim completed his medical school training at Mayo Medical School in Rochester, MN, his residency at Wright State University, and his fellowship at the University of Michigan.
How did you become interested in heart valve technology?
When I came to the University of Virginia 15 years ago, the only established percutaneous therapy for heart valve disease was balloon mitral commissurotomy for rheumatic mitral stenosis. I had been trained to do that procedure, but prior to my arrival, it wasn’t available in the commonwealth of Virginia. While initially a niche therapy, I decided to focus on helping patients with heart valve disease. I started our humanitarian collaborations in developing countries to both maintain my experience with rheumatic heart valve disease therapies, as well as to find ways to contribute–particularly to impoverished patients without other avenues available to them. As I continued in this, I discovered I really appreciated being able to provide
less invasive therapies to such patients. From there, I got into the original randomized trials for both TAVR (transcatheter aortic valve replacement) and MitraClip, and have continued to help expand what is available to patients with heart valve disease.
Are most physicians aware of the minimally invasive techniques available for repairing heart valves? What are some of the barriers to access to these procedures in patients who are not candidates for traditional heart surgery?
Many physicians are aware of TAVR now, and adoption of that less invasive therapy is spreading rapidly. However, I think that many physicians are not aware that we have ongoing clinical trial endeavors on how to repair or replace the tricuspid, pulmonic, and mitral valves as well. I think the first barrier to access for patients with heart valve disease who are not good surgical candidates is our knowledge base. We jumped into aortic valve disease and had success in part because that disease, and the therapy for it, is relatively binary. For example, it is either severe or it’s not, and the patient is either symptomatic or is not, and the therapy is all about getting a new valve in there. Conversely, for the other valves such as mitral or pulmonic, it is a more complex disease process, both in the diagnosis and imaging, as well as the treatment options. We are just on the forefront of learning so much more about treating atrioventricular valve disease.
You were involved in piloting MitraClip therapy for mitral regurgitation. What is unique about this technique?
There have been a number of different transcatheter therapies for mitral regurgitation, and what is unique so far about the MitraClip is its success. We’ve learned that mitral regurgitation is complex, and that of all the other therapies that have been tried, the Mitraclip is the only therapy that has been through randomized clinical trials here in the U.S. and has been approved for use in a select population of patients with degenerative mitral regurgitation. We certainly have come a long way in our learning about who would optimally benefit, and how to optimally use the MitraClip. At present time, for the majority of patients with mitral regurgitation, we approach them as a multi-disciplinary team, looking at them with a number of therapeutic options in mind, such as open surgical repair, robotic surgical repair, mini-thoracotomy approach, standard valve replacement, MitraClip, and even percutaneous or transcatheter valve replacement options. At the end of the day, this allows us to tailor our approach to both the patient and the patient’s valve.
One of the reasons why the MitraClip has had success for treating certain patients with degenerative mitral regurgitation is that the operator can grab the pathologic mitral tissue into the clip’s arms, and even place multiple clips together to do so. All this can be done in real-time on the beating heart, with 2- and 3-dimensional echocardiographic visualization, to sort out the effect of the therapy on the mitral regurgitation. This is unique compared with open surgical approaches, which rely on cardioplegia and cardiopulmonary bypass, in which case your ability to assess the efficacy of the approach is limited.
You were the top award recipient of the Cardiovascular Research Technology’s Cardiovascular Innovations Award this year for your work in developing the Trialign System to perform transcatheter tricuspid repair. Could you tell us a bit about this interventional option?
The Trialign system was designed in partnership with the company Mitralign. We had the idea to modify their mitral valve repair system, so that it would work for patients with tricuspid regurgitation. At present, tricuspid regurgitation is both under-appreciated and under-treated, and there are no approved interventional options for it. The surgical options also have issues that make it not ideal in all patients, and, in particular, not for high-risk patients. The Trialign system uses radiofrequency energy to perforate the tricuspid annulus and throw pledgeted sutures at set places across the annulus, with the goal of placating the annulus and turning a regurgitant tricuspid valve into a competent bicuspid (tricuspid) valve. We did the early animal work, and now we are conducting an early feasibility study here in the U.S. The initial experience in compassionate use options in Europe has been quite encouraging, and we are learning a tremendous amount while helping some high-risk patients.
Last year you joined the TranScatheter Aortic Valve Replacement System U.S. Feasibility Trial (SALUS) as national co-principal investigator, along with Dr. Isaac George. What are the aims of this study, and where do things currently stand?
The SALUS trial is evaluating the DirectFlow Medical (DFM) transcatheter heart valve in high and extreme surgical risk patients with aortic stenosis, and comparing the outcomes in a randomized fashion with patients receiving a clinically approved transcatheter valve. We obtain anatomic data using CT scans on every patient prior to the patient being randomized to receiving either the DirectFlow valve or any of the commercially available valves, and at the end of the trial, not only will we better understand the benefits of some of the unique features of the DFM valve, we will have randomized clinical trial data helping us to better know the answer to “what valve for what anatomy.”
It is an exciting trial and enrollment is underway, with over a third of the trial having been enrolled already. We are also anticipating presentation of the 2-year data from the original SALUS feasibility study, which focused on reduction in aortic regurgitation, conduction system disease, and other complications after TAVR.
You started a partnership between the University of Virginia and Cedimat Hospital in the Dominican Republic for care and education on rheumatic heart disease. Could you tell us about what inspired your work in Santa Domingo and what projects you have underway there?
When I decided to focus on helping patients with heart valve disease, I initially focused on rheumatic mitral stenosis. I realized that a humanitarian collaboration in a developing country would both maintain my experience with this procedure, which is relatively uncommon in the U.S., as well as find ways to contribute to impoverished patients. I made a connection with a Dominican colleague there, and this has led to three to four missions per year, with both open surgical valve missions, mitral balloon valvuloplasty missions, and, more recently, TAVR missions. Underlying all of this is the teaching of the local physicians so that they will need our involvement less and less in the future.
What are some of your clinical and research goals for the coming years?
In addition to my current projects involving the aortic valve (SALUS trial), mitral valve (MitraClip in the COAPT trial) and tricuspid valve (TriAlign device in the SCOUT trial), we also have just begun what will be a series of clinical trials for children and young adults with pulmonic valve disease. The first trial is with an existing valve from Edwards Lifesciences, the Sapien 3 valve, and in the COMPASSION-S3 trial we are evaluating it for transcatheter valve replacement in failing pulmonic conduits. We will then branch out to newer options in patients with native right ventricular outflow tracts.
I anticipate that we will spend the next decade focusing on improving our therapies for heart valve disease.
Katlyn Nemani, MD, is a physician at New York University.
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