It's Your Health Radio, a special podcast series presented by Henry Mayo Newhall Hospital. Here's Melanie Cole.

Melanie Cole (Host): The terms heart attack and cardiac arrest are so often used interchangeably, but they're really quite different events. Today, we're going to explain the difference and also address risk factors, signs and symptoms of each and treatments available.

Welcome to Its Your Health Radio with Henry Mayo Newhall Hospital. I'm Melanie Cole. And joining me today is Dr. Abhishek Sinha. He's an interventional cardiologist and the Structural Heart Director at Henry Mayo Newhall Hospital. Dr. Sinha, it's a pleasure to have you join us again today. I'd like you to just start by telling us the difference between cardiac arrest and heart attack. We've heard of these terms. Tell us what they mean.

Dr Abhi Sinha: Of course. Thank you for having me here, Melanie. It's good to be back. So as you mentioned, in the popular press, people often use the terms heart attack and cardiac arrest interchangeably. But they are distinct from each other and it's important to know the distinctions as well as, probably even more importantly, knowing how to recognize these, how to treat them and hopefully, in cases, prevent them.

This is a topic that's gotten a lot of attention because there's some high-profile cardiac arrests that have captured the nation's attention in the media. For example, the cardiac arrest of the Buffalo Bill Safety, Damar Hamlin, which got a lot of attention and put a spotlight on cardiac arrest.

To describe the differences, let's first talk about what a heart attack is. A heart attack occurs when there is either blockage in the artery to the heart or severe narrowing. If this occurs long enough, it can lead to permanent damage into the heart muscle. That is what a medical definition is of a myocardial infarction.

To get technical, there's technically two different types of heart attacks that kind of most people think about when they think about a heart attack, is a blockage in the artery from atherosclerosis or plaque buildup in the heart artery. We're going to focus on the type 1 type heart attack or mycardial infarction.

So, the heart has three arteries one in the front, one in the side, one in the back. And each of those arteries also have little branches. So depending on which artery is affected, where it's affected in the artery, that can determine whether or not a heart attack is large or small. So, one of the difference between a heart attack and a cardiac arrest is that you can have small heart attacks. So, I've had cases where patients came in with chest pain, we treated them. It was a small heart attack and so there wasn't much damage And so, patients would ask me afterwards, "Well, did I still have a heart attack?" And technically, they did. If they had damage to the heart muscle from a blocked artery or reduced blood flow, that's by definition a heart attack or myocardial infarction. We diagnosed those first by symptoms, then by EKG, checking blood work to see if there's something in the blood called troponin. Troponin is a protein that's found in the heart muscle and it's very specific to the heart. So if we see that in the blood work, that means that they've had a myocardial infarction. And then also, we can do an ultrasound of the heart to look at how the walls are moving and see if there's any part of the heart that's not contracting normally. So, that's essentially how we define a heart attack.

Now, the difference between that and a cardiac arrest is a cardiac arrest is when the heart just stops beating and then stops pumping blood to the rest of the body. And when this happens, the person will collapse, they'll lose consciousness, they'll lose their pulse, they'll stop breathing. And that is a catastrophic event, and it's obviously an emergency. And if the person does not get resuscitated right away, it will lead to death.

Again, within the cardiac arrest terms and in the medical literature, it's defined a couple different ways. Just to explain it briefly, the term that's often used is sudden cardiac arrest, and what that means is that the event occurred without much warning that the person did not have a lot of symptoms ahead of time, and it just happened suddenly. And again, if the person does not get resuscitated quickly, then it will lead to sudden cardiac death.

So, the difference between sudden cardiac arrest is them having the arrest. Sudden cardiac death means that the patient did not get resuscitated quickly or the resuscitation was not successful, and that's sudden cardiac death. Although in the medical literature, sometimes people will use a term sudden cardiac death to apply to both, just the fact that the patient had a cardiac arrest that was unexpected and without warning.

Now, the difference again between that and a heart attack is, again, remember the heart attack is because of a blocked artery results in decreased blood flow and then to heart damage in the tissues. Now, when you have a cardiac arrest, when if it's truly sudden without warning, that's usually believed to be due to an electrical abnormal heart rhythm. And because it's so fast and without warning, it's often believed to be either one or two rhythms, one called ventricular tachycardia and the other one's called ventricular fibrillation. These are both highly dangerous rhythms, and they come from the bottom part of the heart. To explain what they are, you have to understand how the heart physiology works. So, I think most people know that the heart has four chambers. It has a right side and left side. Blood comes to the right side first, it gets pumped out to the lungs, gets to the left side and the left ventricle, which the main pumping chamber, pumps it out to the rest of the body.

But the way the electrical system works is that you have two chambers in the top called the atrium. And then, two chambers in the bottom called the ventricle. There's a pacemaker cell in the top part of the heart, the top right side, the right atrium called the SA node that fires an electrical signal. That signal spreads to the top part of the heart, the atrium and the atrium contracts. Then, the signal goes to the bottom part, the ventricle, and that ventricle contracts. And that's how a heartbeat works. You get the SA node firing, you get the atrium to contract, you get the ventricle contract. That's how a normal heartbeat works in order to pump blood to the rest of the body and perfuse the rest of the body.

When you have an abnormal rhythm like ventricular tachycardia, it means that instead of the SA node firing and the top part contracting, then the bottom part contracting in an organized fashion, you have an abnormal rhythm that's originating from the bottom part of the heart. It often creates an abnormal circuit and it starts racing at very fast rates. It could be 170, 180, over 200. And because it's contracting so quickly and in a disorganized way, the heart is not getting time to fill and pump blood to the rest of the body. And so when that occurs, it's catastrophic because all of a sudden the heart is not pumping blood to the rest of the body, the person collapses and they go into a cardiac arrest.

Ventricular fibrillation is even more dangerous than particular tachycardia. That's essentially an unorganized rhythm, believed to be caused by these small circuits and micro circuits in the heart. And again, when that happens, the heart is not getting time to fill with blood, it's not getting time to pump to the rest of the body. And that's what causes the most of the cardiac arrest. And that's why it can happen so suddenly and without warning, is because it's a fast electrical rhythm. So, that's one of the important distinctions in the physiology.

I will say one part where it does get a little murky, is that one third of the cardiac arrests are not witnessed. So in those cases, we don't necessarily know did that person have symptoms ahead of time. I'll give you an example. Just not too long ago, I got called to the hospital to see a patient, this was a woman who had chest pain at home. She got in an argument with her husband. She had chest pain. It lasted several hours. And then, she decided to go to the emergency room. EKG showed that she was having a heart attack. And while they were getting her a stabilized in the emergency room, she went into that ventricular tachycardia rhythm. She had to get shocked. Then, she went into ventricular fibrillation and we shocked her eight times in the emergency room before taking her to the cath lab where we found that she had a blocked artery. And then, we opened it up and after that, the rhythm went away. So, there are probably cases where someone did have symptoms. But if you didn't have a chance to talk to them before the cardiac arrest, you may not know that.

As far as cardiac arrest, as far as health concern, it is a big health concern because studies have shown that there can be about 350,000 cardiac arrest deaths in the United States, and the survival outside of the hospital is fairly poor. The survival of a cardiac arrest outside of the hospital is about 10%. Cardiac arrests that occur at home, the survival is unfortunately even worse, it's about 6%. And so, the factors that are important to help improve survival is getting CPR right away. So, bystander CPR is probably the biggest factor that helps improve survival in those cases. Having an AED or defibrillator nearby is also important for improving survival. The time which first responders get to the person who's having the arrest is important for survival. All those factors are important, and also just the underlying condition that the person's in.

Now, as far as like what causes these things, we said that in heart attacks, that's from atherosclerosis or plaque buildup leading to a blocked artery. In cardiac arrest, most of the causes are from coronary artery disease or ischemic heart disease, whether it's from a blockage in the artery or prior scar, that's commonly the pathophysiology in those cases, about 75% of the cases are from coronary artery disease or ischemic heart disease.

But there are other causes. A cardiomyopathy, meaning that a heart muscle is weakened from causes not related to a heart blockage, can also cause that. For example, a viral cardiomyopathy, if someone had a virus, for example, we've seen a lot of those during the COVID pandemic and where people have a cardiomyopathy, that causes abnormalities in the tissue, which causes abnormalities in the circuitry of the heart, which can lead to these rhythms. Some people can be born with a cardiomyopathy, and that can also predispose them to abnormal heart rhythms. Example would be something like arrhythmogenic right ventricular cardiomyopathy, is something that people are born with, where the right side of the heart doesn't have normal tissue. The tissue gets pathologically replaced with fibrous fatty tissue, which leads to the substrate for abnormal heart rhythms. You can have cardiac arrest from purely electrical causes, which means that the heart is structurally normal as far as we can tell. And this is where people can have abnormal dangerous heart rhythms due to exercise or emotional stress.

Melanie Cole (Host): So, let's talk about symptoms, Dr. Sinha, because I think that is what worries the most of us. And I'm a woman in my late 50s, so every little chest pain I get, I am thinking, "Is this it? Am I having a little heart attack or am I having a cardiac arrest?" And we all wonder the same. And I know that the difference between women and men as far as our symptoms is something that's very important to note. But while you're telling us these symptoms and the differences between women and men, can you please tell us if we get these little shooting chest pains, people don't always want to run off to the emergency room for all of them, and some of them could be caused by gas or, as you mentioned, stress. Can you tell us how, if at all, we can tell any of the difference for that?

Dr Abhi Sinha: Sure. So with regards to a heart attack, the symptoms, the classic symptoms would be chest pressure or pain, often crushing pressure or pain. Sometimes it can radiate to the jaw, sometimes it can radiate to the arm. People can get nauseous, sweaty, short of breath with that. But as you mentioned, people can also have atypical symptoms. Particularly in women, the symptoms may not present in the classic way. Sometimes it may feel like heartburn or upset stomach. Sometimes it may be just shortness of breath. We see that in diabetics too, because diabetics don't often feel chest pain because of the neuropathy.

I'd say certainly if somebody's having severe chest pain, they should go to the emergency room. If they think they're having heartburn, it would be hard to completely tell if that's from the heart, but heartburn would usually respond to something like Maalox or Tums, if it's really from a GI cause. So if it's not responding to that, if it's ongoing and it's severe and you're short of breath and is starting to have other symptoms, you should get evaluated to make sure it's not something more serious

A lot of times people get non-cardiac chest pain, and that's usually sharp shooting pains that only lasts a couple seconds, that's usually musculoskeletal pain. Short of a heart attack, you can tell if heart-related symptoms are usually related to exertion. For example, if you had either whether it's chest pressure or jaw pain or arm pain every time you go up the stairs, every time you go up a hill, something related to exertion, that would be worrisome, that it's related to the heart. If you had pain just out of the blue, like a sharp shooting pain that lasted a couple seconds, but then when you went to go up the stairs and when you exercise, you didn't have the pain, that'd be less likely that it's related to the heart.

Melanie Cole (Host): I am so glad that you pointed that out. That is such an important distinction for people and it sorts it out so clearly. So doctor, what do we do? If we get those short, sharp ones and we go upstairs and it doesn't bother us, okay. If we get that pressure, the jaw, the back, the arm, if we get that sudden dizziness or nausea, clammy, sweating, any of those things that would signal that we're having a true cardiac event, what do we do? Do we still take an aspirin? Obviously, we call 911. But is there anything we can do while it's happening?

Dr Abhi Sinha: Yeah, I'd agree with taking an aspirin. I have seen cases where people have been coming in with a heart attack and they took an aspirin and they got nitroglycerin by the paramedics. And by the time they came to the hospital, it actually resolved just with that. Most of the time, that's not enough, but it can happen.

Most people are not going to have nitroglycerin unless you already have history of heart disease. But getting help right away is probably the most important thing. I've seen people who've had those symptoms and they just waited. I've seen cases where people had symptoms at night and they waited until the morning to get evaluated. And at that point, a lot of the heart tissue already damaged and that can't be reversed. As far as like symptoms of a cardiac arrest, because it's sudden, usually the person who's having the event may not have time to do a whole lot. It's really going to be up to people who are around them to call for help and start the resuscitation efforts, which is critical to their survival.

Melanie Cole (Host): This is such important information, Dr. Sinha. And just tell us briefly what happens. We hear about stroke and the treatments and things along those lines, and even those symptoms. But for heart disease and heart attacks, what happens at the hospital? Are there interventions that can really save a person's life and then they go into cardiac rehab? Just give us a very brief overview of what you do when you've determined that someone has either had heart attack or cardiac arrest.

Dr Abhi Sinha: Of course. So if someone's coming in with a suspected heart attack, the most important thing they do first is an EKG. And the EKG helps triage on like how large of a heart attack it is. And if it's a heart attack where we see something called ST elevations, that typically means that a major artery is completely blocked. And those patients have to go to the cath lab right away where we take a picture of their arteries. And if there's a blockage, we open it up and put in a stent and restore the blood flow. And that has been shown to improve survival and improve wellbeing because it preserves heart tissue, heart muscles. If it's a smaller one, sometimes that can be just treated with medicine through aspirin, blood thinners, they'll go on cholesterol medicines such as statins and so forth. And then afterwards, depending on how they do, they would get cardiac rehab as an outpatient.

Melanie Cole (Host): Now, I'd like you to wrap it up for us. Give us your best advice as a cardiologist, an interventional cardiologist, Dr. Sinha, what you would like us to know, the difference between a cardiac arrest and a heart attack, but really and most importantly, the ways to prevent them and the ways to recognize them. I think that's really the crux and the key message we want to get out here today, is for the listener to know the difference and to understand how to recognize them, and if there is a way to prevent them.

Dr Abhi Sinha: Sure. One thing I did want to mention just briefly, we talked about the treatment with the heart attacks, but the treatment for cardiac arrests, we touched upon briefly and that's getting help in doing CPR on the person as soon as possible. And that's really critical for people to be able to do CPR and start right away. I think what happens is a lot of times, when patients or people don't get immediate CPR, they don't get blood flow to the brain. And then if you just wait for the emergency personnel to arrive, there could be irreversible brain damage. So, it's important to start CPR right away. First, call for help, call for an ambulance and then start CPR.

It's important to learn how to do CPR properly, and you can learn that through courses. But brain tissue starts developing damage between four to six minutes of not receiving blood flow. And then after seven minutes, you can get permanent damage. And I've seen cases where the EMS arrives and they're able to get a heartbeat back and a blood pressure back, but then the person has permanent brain damage and doesn't wake up. And that's obviously devastating and agonizing for the family because then they have to make some tough decisions later on.

As far as prevention, because most of this is due to coronary artery disease and atherosclerosis, the things that help prevent that can help prevent both heart attacks and cardiac arrests. So, big thing is if you smoke, stop smoking. If you have diabetes, that needs to be under tight control. If you have high cholesterol, that needs to be under control. Exercise can also help prevent development of cardiac disease, so that's important as well. And don't ignore the importance of a diet. The Mediterranean diet has been shown to help reduce heart disease and probably the healthiest diet would be a whole food, plant-based diet.

The other thing that I'll say that's important for people as far as preventing cardiac arrests is people may have warning signs before they actually have the cardiac arrest. So if you are having spells where you're passing out especially with exertion or emotional stress, that should get evaluated. You should see a doctor, get an EKG and further testing if necessary. If you have a family history of people dying prematurely, meaning less than age of 50 for unexplained causes or causes related to the heart, you should get evaluated to make sure you don't have a genetic condition or a congenital abnormality.

Melanie Cole (Host): Thank you so much, Dr. Sinha, for joining us today. This important information could save someone's life. Thank you so much. And to learn more, you can visit the free health information library at library.henrymayo.com, and type cardiac in the search box. That concludes this episode of Its Your Health Radio with Henry Mayo Newhall Hospital. I'm Melanie Cole. Thanks so much for joining us today.