Why Heart Transplants Are So Rewarding and So Challenging Today

Demand for heart transplants still outstrips supply, but other advancements are improving the practice, says transplant cardiologist Ajay S. Vaidya, MD, of the USC Cardiac and Vascular Institute.

The number of heart failure patients needing a heart transplant has steadily grown year over year. Despite this, the number of donors and heart transplants performed annually remains unchanged. While this hurdle persists, clinical advancements have led the field forward in other ways, including personalizing treatment to improve the experience of heart transplant patients overall.

Despite more patients progressing to heart failure, we still don’t have many treatment options for people with end-stage heart failure. Those options are still pretty much either a heart transplant — or implanting a left ventricular assist device (LVAD) and then eventually getting a heart transplant.

The number of heart transplants performed each year in the U.S. hasn’t grown, however. It’s remained pretty steady over the last three decades. So, we have a growing number of patients who need a heart transplant — but a limited number of heart transplant donors and heart transplants as a result.

Heart transplants are largely successful.

The limited number of transplants is unfortunate because the survival rate for heart transplant is enormously good — usually about 90%-95% at one year, and an average survival of around 12 or 13 years, meaning that 50% of patients are alive at that point. Compare this to end-stage heart failure survival rates, which a major clinical trial showed was 25% of people alive at one year and 8% of patients alive at two years.

That’s what makes heart transplantation so rewarding. You are able to provide a therapy that can save a person’s life and help them go from a limited quality of life, with very severe symptoms, to a fairly normal quality of life. We’ve seen people who received a heart transplant run marathons and climb mountains. Just being able to return that outcome to patients and their families is the best feeling in the world.

Noninvasive surveillance makes post-transplant monitoring easier.

For those fortunate to receive a heart transplant, advances today are optimizing their post-transplant experience.

For instance, for nearly 50 years, the standard of care after a heart transplant has been to monitor a patient for organ rejection. If the patient’s body attacks the new donor heart, it can result in heart failure and death.

Monitoring was generally done via myocardial biopsies using a catheter to invasively extract a piece of the heart and examine it for signs of rejection. In prior eras, heart transplant patients might undergo up to 18-20 biopsies during the first year post-transplant.

Now, however, we can monitor transplant patients for heart damage noninvasively using blood tests. The researchers at Keck Medicine have taken a national lead on applying and developing these noninvasive surveillance techniques. This includes the use of what we call donor-derived cell-free DNA. Essentially, this test looks at the breakdown of cells, which releases DNA from donor hearts. These biomarkers can indicate rejection or damage to those cells, allowing us to monitor for heart damage noninvasively. Now, we might only conduct one invasive biopsy in the first year. The rest of the tests are noninvasive.

We’re one of the few programs in the country doing this and are setting the paradigm for the practice of heart transplantation. We’ve been able to publish and share our research at national meetings where people have been enthusiastic about our approach.

The ability to personalize treatment has advanced.

Another thing that’s changed in the last decade is our ability to personalize our treatment approach. For instance, one advancement has been in the area of antibodies. Everyone has antibodies in their blood that help fight infection, but people can also have antibodies that attack other human cells. Oftentimes in transplant patients, the presence of such antibodies is considered a risk factor that can hinder a patient’s ability to qualify for a transplant. If someone has a lot of antibodies that could attack a prospective organ, it limits our ability to provide a transplant. However, we now have therapies available that can target some of these adverse antibodies, increasing our ability to find a suitable donor for our patient.

At Keck Medicine, the next frontier we’re pushing is figuring out how to leverage immunosuppression to benefit transplant patients. By using noninvasive monitoring techniques to help us better detect rejection or the risk of rejection at an earlier stage, we can intervene sooner and come up with a more effective, personalized approach.

For instance, if our monitoring shows us that a patient is at less risk of rejection, we can wean off prescribing some of the medications we might otherwise have used to keep their immune system quiet. These medications would generally also have put the patient at a higher risk of infections and organ rejection.

Tools like these are enabling us to personalize our approach to each patient and manage that key balance between fighting rejection and fighting too much immunosuppression. So, for people one year after transplant who haven’t shown elevated cell-free DNA levels, we could potentially lower some of their immunosuppression without raising the risk of rejection — while also potentially saving them from developing future infections or cancers down the road.

More research and development is the goal.

Using these techniques, we are already finding more novel ways in which to personalize care for transplant patients who really need us to think about their medical history individually.

In addition to this, we are working to grow the field of durable LVADs, whose technology is very good. We are one of the top implanting sites of mechanical circulatory supports in the area. We want to lead in the development of specialized destination LVAD centers for patients who have no other options and for whom a pump device can serve as a long-term therapy.

These patients can go from having very severe symptoms to having very few or minimal symptoms of heart failure. We feel like this type of science and technology is not fully utilized in the region, and we want to lead the way so that patients can get the best outcomes possible.

Finally, I think what many people have read about in terms of cutting-edge scientific news is about xenotransplantation (using organs from animals such as pigs and transplanting them into humans). There have been a few cases of this done in the U.S. Unfortunately, none of them worked out in the long term. But we are optimistic that over the next several decades, the field will be moving in this direction, and we hope to lead it through our work in strategically leveraging the immune system in a tailored and successful way.

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