Part two of three on the latest in LVAD [left ventricular assist device] and heart transplantation. An interview with Nir Uriel, MD, Director of Advanced Heart Failure and Cardiac Transplantation. Read Part 1 on Heart Failure here.
Part 2: LVAD and Heart Transplantation
Talk to us about LVAD.
Okay, so this technology has evolved from a bridge to transplant technology—something to give patients a year or two of time to find them a heart, to a technology that can give our patients a long time to live.
We can't really say what the longest time that people can live on an LVAD is, but we can say that we have patients that live more than 15, 16 years on an LVAD. And that the technology is evolving all the time.
What should we know about the latest evolution?
The most recent development was a pump called HeartMate 3. And with the biggest study to evaluate it, called MOMENTUM 3, I had the fortune to be the national PR of the study and run it on the global level. It's the biggest study ever conducted in LVAD support. It was so successful and we finished our recruitment so fast that we opened what's called a continued access program where people can continue to use the pump.
So overall the study had 2528 patients, and it demonstrated that the HeartMate 3 pump has a significant improvement in the survival rate, of disabling stroke, and does not need device exchange. The two-year survival, bridge to transplant destination therapy, you name it, was in the 80 percent range. There is also a significant reduction in the rate of stroke to 8 percent. It's the first time we’ve seen a stroke rate going below 10 percent.
We see complete elimination of device thrombosis, something that we were very concerned with with the previous pumps. And, of course, we also start seeing a reduction in VT [ventricular tachycardia], a reduction in bleeding, and other complications associated with the device. Everything across the board.
This outcome actually challenges heart transplantation. This is a new era. And we hope that the next generation of the device will not include a driveline, or need for the external electrical power source. So, the patient will be completely implanted and not have anything outside of the body.
So, how has transplant changed?
Transplants have seen the biggest jump in the last few years, and the reason for that is actually surprising. It's not that we changed the way we do the heart transplantations, it’s the same surgery, the same immunosuppression medication. But two big changes have happened.
The first one is a sad one so brace yourself–America is facing an opioid epidemic, causing overdose deaths in young people with good hearts. And it’s actually significantly increasing the number of heart donors. Thus reflecting the significant increase of heart transplantation across the country and of course, in our center as well. And this is true for other organs as well.
The second thing is actually something very good. Hepatitis C used to be a disease that didn't have a cure, a blood-borne disease that caused some patients liver cirrhosis. Of course, we did not want to take a heart from a Hepatitis C patient and give it to someone that doesn't have Hepatitis C or has a different strain. And because of that, all the patients, the donors, that were infected with Hepatitis C were rejected from transplant.
But now, multiple great medications have been developed to treat Hepatitis C. Now, the disease has a cure, so we also use donor hearts from those with Hepatitis C. That advance has opened us to more hearts to save more patients.
What about surgery itself, the use of transplant for instance?
If we go to the sickest patient, the one that needs transplant, I truly believe that heart transplant will continue to grow and will continue to get better. We see already that patients after heart transplant on average live 15 years, but we have a lot of patients who live 20 and 30 years post-transplant. And I believe that we will be able to provide even more years.
I think with the new immune medication that we have right now, we'll be able to provide better immunological support to those patients with reduced risk of rejection and reduced risk of coronary disease after the transplant. And that it will open transplant up to people that have a lot of antibodies in their blood and were not able to receive a heart transplant.
How have immune medications changed?
There is a growing understanding that transplant is more complex, we don’t just want to block everything, we need to block a specific area. So, in the past, we’ve really had only three immune medications: CNI inhibitor, BNF, and steroid.
Today, we have other medications that can affect the immune system in other ways. Like blockers and medication designated to affect the B cells and the T cells directly, the antibodies. So we can shut down certain systems with specifically directed therapies, monoclonal antibodies that are specifically directed.
It sounds like there really is so much to be thrilled by, but what are you most excited about for the future?
Oh my god, there are so many things. I think for me, heart failure is a continuum. I want to be able to identify the patient as early as possible. At Columbia, we just moved to an EMR [electronic medical record], and this stronger medical record may be able to even give us hints for a patient that we would never otherwise think has heart failure.
Specifically, in our group work, we rely very strongly on artificial intelligence and machine learning to identify patients based on their EMR. Not the patient that already has heart failure, rather the patient that came by coincidence to the emergency department because they broke their leg. But, now we can identify some tests that suddenly will say, "Wow. This patient is at risk to have heart failure." And we can treat that now, we can save them before they know they need it.
We’ve touched on so many areas of advancement, do you have one that’s your personal favorite?
Oh, what I love the most is the innovation coming in the field of LVAD. HeartMate 3 was only the beginning. Next, we really need to see how LVAD can be without a driveline like i mentioned earlier—develop a “smart pump.”
You know, our brain is always telling our heart, "Work harder, work faster, work slower." Speaking to what we do when we sleep, when we run, when we're excited, when we are upset. And it affects the pump—we're not fixed people, we have emotion. And we need our artificial heart, or the LVAD, to be able to adjust to this.
Is that smart pump research happening right now?
It is. We are actually very involved with the research associated with the smart pump, and developing a little bit of brain to those pumps that will be able to react to the changes happening in the body.
So LVADS now work on a continuous flow, does that mean you are introducing a heartbeat in some way?
Very interesting question. So continuous flow in the HeartMate 3 for example, we see it rotate from a speed of 52 to 56 hundred revolutions per minute. And every 1.65 seconds we have to decrease and increase the speed that's creating what we call an artificial pulse. But this will not be enough.
When I'm now sitting down with you and talking, my heart is pumping something like 5, 6 liters. In the morning when I was cycling, my heart was pumping 20 liters. So from 6 to 20, there is a three-fold increase in the cardiac output. Pulse will not generate it. What will generate it is a significant change in speed. The pump will do a continuous flow but speed up, and there are some other associated sophisticated elements at play as well.
This may also improve the exercise performance of those patients. Smart pumps will be able to adjust to when the heart needs to work on different volume status, like when eating a lot of salty material or having a fasting day like I did the other day when I didn’t have enough time to eat.