TTHealthWatch is a weekly podcast from Texas Tech. In it, Elizabeth Tracey, director of electronic media at Johns Hopkins Medicine in Baltimore, and Rick Lange, MD, president of Texas Tech University Health Sciences Center in El Paso, look at the week’s top medical stories.
This week’s topics include early ablation of atrial fibrillation, rapid treatment of heart attacks, lowering triglycerides and cardiovascular outcomes, and making defibrillation more effective.
Program notes:
0:51 Heart attack treatment time
1:51 Only 17% of the time according to guidelines
2:51 Each hospital must evaluate
3:50 Thrombolytic therapy
4:01 Pemafibrate and cardiovascular outcomes
5:01 67% with previous CVD
6:04 Higher incidence of adverse renal events
6:23 Refractory defibrillation
7:23 Dual defibrillation had higher survival
8:23 Just experience
8:30 Early treatment of atrial fibrillation
9:30 Much less recurrent fibrillation
10:30 auricular tissue remodeling
11:30 Both done safely in experienced centers
12:49 End
Transcription:
Elizabeth: Does lowering triglycerides help reduce the risk of cardiovascular disease?
Rick: Rapid treatment of acute heart attacks.
Elizabeth: Does early treatment of atrial fibrillation help prevent the disease from progressing?
Rick: And making defibrillation more effective for people who have had cardiac arrest.
Elizabeth: That’s what we’re talking about this week on TTHealthWatch, your weekly look at medical headlines from Texas Tech University Health Sciences Center in El Paso. I’m Elizabeth Tracey, a medical journalist based in Baltimore.
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, of course, this is AHA (American Heart Association) meeting week and so everything this week is about the heart. Since you’re a man of heart, I’ll let you start.
Rick: Well, Elizabeth, we’re talking about one of the most common heart conditions, heart attacks, when there’s a blood clot in one of the arteries that blocks blood flow to the heart and that can cause immediate irregular heart rhythms, in which in case people need to be defibrillated. Or if they survive without a rhythm abnormality, there is some heart muscle that dies. We have a saying that goes: “Time is muscle”. What you want to do is open that artery as quickly as possible to preserve the heart muscle.
This was a study that looked at two different time periods, in 2018 and 2021, of almost 115,000 patients who received heart attack treatment at more than 648 hospitals called the Get With The Guidelines – Artery Disease Registry coronary (GWTG-CAD). They wanted to ask, “What are we doing, and does getting treatment before a heart attack really affect mortality?”
There are several different goals. We want to make sure that the first medical contact when they open the artery is less than 90 minutes. In people presenting to a hospital that does not have a cardiac catheterization lab, this only happens about 17% of the time. In those individuals who have the artery open early, it reduces mortality by around 50%. Anything and anywhere that is delayed less than the guidelines recommend basically doubles the mortality. That’s what this study showed.
Elizabeth: This study is published in JAMA. I would like to hear your thoughts on what accounts for these delays and would it be helpful to contract EMS, for example, to ensure that they are always transported to hospitals that have a cath lab.
Rick: It’s different for different locales. One of the things the authors recommend is for individual hospitals to identify where their backlog lies and fix it. You want to have EMS people trained to recognize a heart attack in the field. They can call the hospital ahead of time and start activating the cardiac catheterization labs.
The second, as you said, is to make sure people get to a cardiac catheterization lab or regional center as soon as possible. For those who have just entered the hospital, it is also important that they are seen very quickly for an EKG, so that we can establish if it was a heart attack and then activate the cardiac catheterization lab. There are a number of different factors, and it’s local. That is why it is necessary to evaluate them at hospital level.
Elizabeth: You say that each hospital needs to take a look at where their delays occur in their particular facility. I wonder how complicated it is to follow someone when they come to your ED and then go through all the assessment and treatment.
Rick: It’s really not that hard. Most hospitals should create committees to do this. For example, you know you want the person from the time they show up to the emergency department to have an EKG in less than 10 minutes. Each of them can be segmented and evaluated.
Elizabeth: One question I have, of course, is that we’ve been seeing a lot about “maternity care deserts” in different parts of the country. Let’s talk about the distribution of cardiac catheterization laboratories.
Rick: You would like, when a person comes to a hospital that doesn’t have a cardiac catheterization lab, it’s to get them out in 30 minutes. Obviously, it is more difficult in very rural areas. In these settings, the patient often receives thrombolytic therapy that should dissolve the clot. It is not as effective as a balloon, but it is still much more effective than not treating the patient and then moving the patient.
Elizabeth: Let’s go to the New England Journal of Medicine, where we’re going to spend the rest of our time this week, looking at heart attack prevention. We know that there are many things that go into someone’s heart attack risk. One thing is high triglyceride levels. It is not clear, however, whether lowering these levels will reduce the incidence of cardiovascular events. This agent called pemafibrate was tested in this study to lower triglyceride levels and also associated with improvements in other lipids. The question is, does this really help?
This was a study that included patients with type 2 diabetes, mild to moderate hypertriglyceridemia, and that was a triglyceride level between 200 and 499, which doesn’t sound like moderate to me, but maybe you’ll disabuse me of that notion. – mg per dl, and low levels of high-density cholesterol.
They were given pemafibrate twice daily or a matching placebo. They had almost 10,500 patients, 67% of whom had previous cardiovascular disease. They were followed for 3.4 years. They saw that pemafibrate was able to achieve a 26%+ reduction for triglycerides, 26% for VLDL, and nearly 26% for remaining cholesterol. The bad news is that it wasn’t really very helpful in terms of those other results they were looking for, even though they did see improvements in that profile.
Rick: This is one of several agents that have been very effective in lowering triglycerides in people with high triglycerides, but it has not reduced the risk of heart attack, stroke, or cardiovascular death.
This is very different from the cholesterol story, and lowering cholesterol, especially LDL, has been beneficial. In this particular study, they targeted a specific population that they thought might be helpful: diabetics, high triglycerides, and low HDL. This was a group that, hey, they thought if anything was going to work this was going to be the group. Again, lowering triglycerides did not actually improve cardiovascular outcomes.
Elizabeth: Yes. It seems like it must be a stand-in for something else going on. In addition, they had a higher incidence of adverse renal events and VTE.
Rick: Relatively minor. Then when they went to look at it, it really wasn’t that big. One of the things that was interesting, though, is that this can have some beneficial effects on the liver. They may divert your attention from using this for cardiovascular disease to liver disease or fatty liver.
Elizabeth: Let’s move on to your next one, like I said, also in NEJM.
Rick: I mentioned the fact that when people have a heart attack, one of the complications is an irregular heart rhythm, or what’s called ventricular tachycardia or ventricular fibrillation. This is often what causes death in people who have an out-of-hospital cardiac arrest. There are some people who are just refractory to defibrillation with the typical method.
What these researchers did was say, hey, can we change the defibrillation method a little bit and make it more effective in people who have refractory heart rhythms? The two ways to do this are usually with the paddles placed on the front of the chest. What if you put one in the front and one in the back? The second is to use two defibrillators, one where the paddles are placed in the front and one where they are placed in the front and back, and then defibrillate the patient sequentially.
In this particular study, they tried 3 different techniques, moving the paddles, doing a double defibrillation, and then just trying to repeat the standard fibrillation. What they found was that when they used double defibrillation, it had a higher survival rate than standard, 30% versus 13%. When they only changed the vanes in the front and back, it was also associated with greater survival, 22% versus 13%. This is great news regarding the success of refractory defibrillation.
Elizabeth: I’m going to ask you to think back, many years ago, to the idea that CPR should be given dorsally versus ventrally. Talk to me about why this might work.
Rick: When you think about where the heart is, where the left ventricle is, a lot of it is in the back, the back of the heart. When you place the paddles only on the chest wall, you don’t get as much…