Comparing Two Types of Mitral Valve Repair; Circulatory Death and Donor Hearts

— Also in TTHealthWatch: benefits of oseltamivir, family-based approach to obesity treatment


TTHealthWatch is a weekly podcast from Texas Tech. In it, Elizabeth Tracey, director of electronic media for Johns Hopkins Medicine in Baltimore, and Rick Lange, MD, president of the Texas Tech University Health Sciences Center in El Paso, look at the top medical stories of the week.

This week's topics include the best way to perform mitral valve repair, a family-based approach to childhood obesity, circulatory death and donor hearts, and benefits of oseltamivir.

Program notes:

0:40 Circulatory death and donor hearts

1:40 Half from those who had circulatory death

2:40 Maintaining donor organs

3:53 Family-based behavioral treatment for childhood obesity

4:53 Also siblings and parents

5:54 Need to have less intensive ways

6:54 Agree that prevention is preferable

7:11 Two types of surgery to repair mitral valve

8:11 Compare open versus minimal surgery

9:11 Not inferior?

10:00 Oseltamivir and hospitalization

11:01 Over 65 and those with other comorbidities

12:54 End


Elizabeth: Does a family-based, comprehensive approach to obesity help in kids?

Rick: Increasing access for donor hearts for people that need heart transplantation.

Elizabeth: Does oseltamivir help keep people out of the hospital when they have the flu?

Rick: And comparing two different ways of repairing the mitral valve, one done in the United Kingdom and one done in the United States.

Elizabeth: That's what we're talking about this week on TT HealthWatch, your weekly look at the medical headlines from Texas Tech University Health Sciences Center in El Paso. I'm Elizabeth Tracey, a Baltimore-based medical journalist.

Rick: And I'm Rick Lange, president of Texas Tech University Health Sciences Center in El Paso, where I'm also dean of the Paul L. Foster School of Medicine.

Elizabeth: Rick, how about if we turn to the New England Journal of Medicine and this soft toss to you as a cardiologist. Go ahead. What about those donor hearts?

Rick: As everybody is aware, there are thousands of individuals who need heart transplantation, not only in the U.S., but around the world. There aren't enough donor hearts. Frequently they are put on mechanical devices that the outcomes aren't quite as good as having a heart transplantation.

Typically a heart transplantation occurs with donors that are determined to be brain dead. There is a separate group of people that didn't have brain death, but actually had circulatory death. What this study looked at was, what is the suitability of these hearts for transplantation? That is, once a person has experienced circulatory death, within 30 minutes you're able to harvest the heart and then at that point you put it on a perfusion machine that allows blood to flow through it, and you can determine how well it works, use that for a donor heart in a person who needs a heart transplantation. That's what these individuals compared.

There were 180 patients that underwent a transplantation. Half had a donor heart, typically from a person that was brain dead, the other half from individuals had experienced circulatory death. What they looked at is 6 months after the transplantation what was the percentage of people that were alive and didn't need a retransplantation. The 6-month survival among both groups was about 94% and importantly, when they had somebody that experienced circulatory death, they were able to use about 90% of those hearts. This expands the available number of hearts for individuals around the country.

Elizabeth: Since you brought up that point, one of my first questions is, of course, how much will this contribute to the availability of donor hearts?

Rick: Well, Elizabeth, it's hard to know the exact numbers and this paper didn't specifically say that. What they did determine is, by having the capability of using either particular heart, it shortened the time the individuals waited for their heart transplant.

Elizabeth: Clearly, this is a time-limited kind of an interval. I will recall for our listeners and for you that we just discussed a study looking at kidneys being maintained on exactly these kinds of devices. I had told you, "Yep, I have heard about this with regard to lungs." Now we're hearing that with regard to hearts it's successful. I would like to hear your speculation on why we seem to be seeing these disparate results with different organs.

Rick: Sometimes it's based upon how well the organ deals with what's called ischemia -- that is having no flow. Second is how well we're able to reperfuse it. Then how do you measure that?

With the heart, it's real easy because it's an organ that pumps. It's more difficult with a lung or a kidney if you put it on a perfusion machine because you don't know if the lung is going to work. You don't know whether the kidney is going to work. In fact, in this particular study, 10% or 11% of the organs that they put on the perfusion machine they decided weren't suitable for transplantation.

Elizabeth: I think I'm going to just foreshadow here that we're going to see a study that's going to attempt to identify what factors there are in these different organs that indicate their viability once they're put into a perfusion machine.

Rick: You'd like to be able to assess viability relatively early, because you want it on the perfusion of machine for a shorter time as possible. And for organs that either metabolize or excrete things like the kidneys or liver, it may take longer to figure that out. With the heart, it's pretty quick.

Elizabeth: I bet that's why you like hearts, isn't it?

Rick: Among other reasons.

Elizabeth: Let's turn to JAMA. This is a look at a family-based behavioral treatment for childhood obesity that was implemented in a pediatric primary care setting. We all know, of course, that we are having this onerous problem with obesity, and obesity has its roots in childhood.

In this randomized clinical trial undertaken in 4 U.S. settings, they enrolled 452 kids who were 6 to 12 years of age with overweight or obesity, their parents, and 106 of their siblings. They were assigned to undergo either family-based treatment or usual care for obesity, and were followed up for 24 months. Their primary outcome measure was the child's change from baseline to 24 months in the percentage above the median body mass index in the general U.S. population normalized for their age and sex. Secondary outcomes were the changes in this measure for the siblings and the BMI for parents.

After following them up, they did find that there was a short-term improvement for everybody, a child who had overweight or obesity, for the siblings, and for the parents. They were able to demonstrate also that they could implement this in a primary care setting with people who were untrained in this particular intervention previously. That would be fewer resources needed in order to implement it. However, what's the fly in the ointment? I'm turning to you now.

Rick: All right, a couple of flies. One is, as you said, there is a short-term benefit. It looked like in 6 months they lost about 6% of their weight, but by 24 months they had regained it back. Although there is some benefit, it's really minimal and it's really not very durable. Unfortunately, this was still a pretty intensive therapy. It occurred over 26 different sessions, usually weekly, then bi-weekly, then quarterly, and then semiannually. I don't think we could actually roll it out. What it does tell us is that we need to have ways that are just as effective, less intensive, and have durability.

Elizabeth: I still am constantly brought back to a notion of prevention, feeling like that's what we need to do with children and with adults. We have talked so many times about the fact that weight gain is a gradual process. At everyone's interaction with the healthcare system, this ought to be monitored. When the trajectory is pointing in a direction where there is weight gain above what's reasonable or appropriate for age, sex, and all those sorts of parameters, that's when we need to step in and say, "Hello, guess what? We see that there's a problem emerging. What can we do right now?"

Rick: Elizabeth, as you know, it oftentimes "runs" in families. Childhood obesity oftentimes follows adult obesity. You can't engage a child in this program if you don't engage the parents. The parents are the one who buy the food. They make the food. They encourage the child, and also emulate what kind of physical activity, what are healthy lifestyles in terms of sleep and in terms of activity. You and I both agreed upon this: prevention is better than treatment. Different treatments are available, the behavioral therapy, we know the pharmacologic therapy, and we're now doing surgery in kids as well. But if we could prevent it, that's really where we get the most benefit.

Elizabeth: Staying in JAMA then.

Rick: Elizabeth, I teed this up as two different types of surgery for mitral valves. When you look at the heart valves that are most likely to be diseased or leaky, the mitral valve, the one between the left atrium and the left ventricle, is the most frequent valvular heart disease.

Now, it can occur because the heart swells and the leaflets just can't touch one another. The leaflets are fine. That's about two thirds of the time. But about a third of the time, the leaflets are diseased some way, and in the past we used to replace the whole mitral valve. But what we've determined is actually if we can fix them, we're better off than if we can [replace] it.

Fixing the valve in the U.S. is typically through an incision right in the middle of the chest, through the sternum, called a median sternotomy. However, in Europe, they do it through what's called a minithoracotomy -- that is, they use a video-assisted device to make a small incision between the ribs, and they do the mitral valve through there. Allegedly, they do it because they feel like the patient can return to function better. They don't have quite as big an incision to recover from, with just as good a result. But nobody has ever really tested that in a randomized controlled trial.

That's what this particular study did, is they looked at over about a 4 or 5-year period. They had about 300 individuals that needed to have their mitral valve replaced. About half of them had it through the usual way we do in the United States, and the other half had it done the usual way done in the United Kingdom. By the way, these are by experienced surgeons. The outcome at 12 weeks was no different. Having the minimal surgical procedure didn't get people on their feet any faster. The results of the surgery were just as good; about 95% of the time they were able to repair the valve with very minimal leaking after this.

Elizabeth: I have point out the phraseology that people use in order to delineate their conclusions. In this case, it says the minithoracotomy is not superior to sternotomy. We employ other phraseology. We could have said is not inferior to and I think that the nuance there is actually really pretty important. I wonder about how that plays out in discussions with patients. If somebody said to me, "Look, I can do this by this little tiny incision," or, "I can crack open your chest," there is no question of which one I would choose.

Rick: What I would say is it was hypothesized that the smaller incision would mean that the person would recover faster at 12 weeks and what you can say is, it's not superior.

Elizabeth: I'm just going to remind you that it's spoken like a guy because you're not worried about what you look like in a bikini, but I bet a lot of women would ask that question.

Rick: That's a good point Elizabeth. If that's a concern, then someone needs to seek a surgeon who is particularly skilled in that technique.

Elizabeth: Finally then, let us turn to JAMA Internal Medicine, this was taking a look at the antiviral oseltamivir and whether it actually prevented hospitalizations in outpatients who had influenza. I know that you and I recall that market run on oseltamivir or Tamiflu when there were flu strains that were out there that were of particular concern.

This study takes a look at its meta-analysis, a number of studies, does it really help? This study population was comprised of 6,295 individuals in whom 54.7% were prescribed oseltamivir. Of great interest to me, their mean age was only 45.3 years, so this was the young group. They took the oseltamivir and it was not associated with a reduced risk of hospitalization. They also broke out those greater than or equal to 65 years of age and the same thing, guess what, it didn't really help.

Rick: Not only did they look at the people over 65, because that is a high-risk age group, they looked at other people that have other comorbidities like depressed immune systems, or liver disease, or kidney disease, and the Tamiflu did not prevent them from being hospitalized either.

What does Tamiflu do then? Well, it decreases the symptoms from about 1 day and it does lower the titer a bit. But I was really surprised because this whole time I thought that Tamiflu would prevent hospitalizations and particularly in higher-risk individuals.

Elizabeth: This is a medication that's been out there for so long that's been employed and now we're looking at it more carefully and saying, "Oops, it doesn't look like it really helps at all. Maybe we ought to throw this one out." They point out in this paper that many of the trials that have been used to inform much of what we thought was our knowledge base were industry trials.

Rick: Yep. In fact, some of the industry trials didn't show any benefit. One of the points that they made when they talked about the limitations of the study is, because there is such a small percentage of people who get hospitalized, the number of patients you have to analyze is going to be 15,000 or 20,000 or 25,000 to show any benefit at all. But then you get into the cost-benefit analysis. I mean, are you going to give 30,000 people Tamiflu to prevent one or two deaths and what's the cost to society?

Elizabeth: Is it going to cause you to toss out the Tamiflu?

Rick: I think you tell the individuals, "Listen, if you start taking Tamiflu, you'll have symptoms for a lesser amount of time but it's not going to prevent the risk of being hospitalized." Then I think the patient gets involved with whether or not they want to. Because there are some side effects from taking Tamiflu, mainly GI side effects.

Elizabeth: What this makes me say is, should this stuff even be on the market?

Rick: If it's important to the patient to have fewer symptoms and they're willing to risk the increased risk of nausea and vomiting, that's their decision.

Elizabeth: On that note then, that's a look at this week's medical headlines from Texas Tech. I'm Elizabeth Tracey.

Rick: And I'm Rick Lange. Y'all listen up and make healthy choices.