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Doctors Matt DeVane and Carolyn Lacey discuss the significance and process of various types of stress tests with their colleague Dr. John Vu. They explain what patients can expect from these tests, as well as how the tests help evaluate heart health and diagnose potential heart conditions.


Matthew DeVane, DO FACC: [00:00:08] Hi, I'm Doctor Matt DeVane.

Carolyn Lacey, MD FACC: [00:00:09] And I'm Doctor Carolyn Lacey. We are cardiologists at John Muir Health and this is our podcast, Living Heart Smart.

Matthew DeVane, DO FACC: [00:00:16] Our physician partners and colleagues are going to help guide you through many different and important cardiovascular topics to help keep your heart happy and healthy.

Carolyn Lacey, MD FACC: [00:00:24] Thank you for listening and we hope you enjoy our show.

Matthew DeVane, DO FACC: [00:00:34] Many patients come to cardiologists because of heart symptoms like chest pain or shortness of breath, or just because they have higher risk for coronary artery disease. You may be asked to do a stress test. That's a great way for us to evaluate the blood flow to your heart. Doctor Lacey and I, welcome back to the program, Doctor John Vu. We've asked Doctor Vu here today to talk about the different types of stress tests your doctor may want to order. I think hearing about the stress test from a cardiologist will really help ease some of your anxiety that you may have going into a stress test. They're really safe and effective. There's two main types of treadmill stress tests. Um, the exercise treadmill test where someone just comes in and they walk for a bit on the treadmill, which we can talk about, and then we think of the second one called a stress echocardiogram, where we add some additional testing. So tell me about what would make you send someone for just a regular treadmill test where they just show up, put a few patches on and start walking on the treadmill?

John Vu, MD: [00:01:35] Well, I think you got to look at the EKG. First of all, from a technical standpoint, the EKG has to be readable if there's some abnormalities on it. You can't, uh, distinguish changes if there's baseline abnormalities. And then the question of adding imaging or not, that increases the specificity and sensitivity. It basically makes the test better for certain patients. Patients that are, uh, likely to have either like a false positive meaning the test might say there's something wrong, but actually there's nothing wrong with you. Uh, so that is a sort of a theory of testing. We won't go into that. But, you know, that's where certain tests are better for certain patients. And so in terms of a regular treadmill, I'd say, number one, the EKG has to be at baseline, uh, interpretable. And we've got to be able to tell with good sensitivity and specificity that the changes are real. And of course, the patient has to be able to walk on the treadmill. I think that's important because, you know, we see quite a number of, uh, older patients, obviously they come in with a cane or they come in with a missing leg, you know, uh, that's not a good candidate for a treadmill. Although they'll say, oh, doc, I can walk. Don't worry about it. This is not the same type of walking that you typically do. Uh, the tests, uh, brisk walk.

Carolyn Lacey, MD FACC: [00:02:54] How do you describe this to patients? They have no idea. They think they're going to be running for half an hour on the treadmill. No, no, thankfully, it's not that way.

John Vu, MD: [00:03:02] It's not that way, but it's pretty intense. I tell them that, uh, the the speed is slow in the beginning, but the incline is what's going to get you. I think the, you know, we use typically called a Bruce Protocol and they can look it up. And sometimes I show it to them and say, hey, this is some homework you got to do because you're never going to walk like this, uh, at these stages, uh, unless you're a hill climber. Because the first stage, even though it's like, I think two miles an hour or something, the incline is about 8 or 10%, and most commercial treadmills only get up to about 15%. And we we started at ten. The next stage in three minutes, you go up to 12 and then stage after that it goes up to 14. And so by the time they got to stage four, you're at 16% incline, which is not typically, uh, what you would do. And uh, I usually calculate for them what their peak heart rate is. That's easy number. It's 220 minus your age. And tell them, look you got to get to about 85% to make the test, uh, valid. And hopefully you can do that. Some patients say, oh, no, no problem. I track my heart rate. This is the peak heart rate I get. I said, yeah, this sounds like a good test. We'll be able to do this well.

Carolyn Lacey, MD FACC: [00:04:15] Are there any modifications that patients can know about for the Bruce Bruce protocol? We talk about it so much. We've been using it for 40 years.

John Vu, MD: [00:04:25] Yeah. There's there's a few other protocols. There's, uh, modified Bruce. There's a, uh, Naughton and there's a few others. Modified Bruce I believe it's just a flat incline. Um, or sometimes there's no incline. It's just, uh, keep the speed the same just for distance. And, uh, at that point, uh, you wonder if maybe they should have just done a pharmacological. But sometimes we use that protocol for other reasons, not just for stress testing, you know.

Carolyn Lacey, MD FACC: [00:04:53] Do you ever do you ever tell the patient what you expect when you look at them, say, well, I think you're going to be able to do X amount of minutes just to sort of get that.

John Vu, MD: [00:05:06] Yeah. So I try to tell them if you can do at least um, 7 to 8 minutes, you're in pretty good shape. Um, you know, if you're not a typical person that exercises. When I was in training, we used to do these firefighters. In order for them to pass, they had to do 15 minutes. So I tell them, look, you can get 15 minutes. You can have another career as a firefighter. Nice. You know?

Matthew DeVane, DO FACC: [00:05:31] Yeah, thats rare if you can see somebody that far.

Carolyn Lacey, MD FACC: [00:05:34] In the military we would see 18, 19 year old Marines at the, at the, at the naval air base or the Navy, the Navy base. And they would have to come, for whatever reason, to have their chest pain evaluated and they would shut down the treadmill. The fellows weren't the one running the treadmill. The techs ran the treadmill so there wasn't a doctor in the room. Otherwise it would have. They would have stopped at 15 minutes, but they would shut down the treadmill and the treadmill stops at 25 minutes.

Matthew DeVane, DO FACC: [00:06:04] I never knew that. I never do that. Yeah. So for me, I mean tread exercise, treadmill test alone, I rarely am ordering those now. So a treadmill test in my mind, an exercise treadmill test by itself. You have to have a normal EKG, a very low risk patient where you really don't think it's coming from the heart, but you just want to be safe and make sure they go through and exert them and watch the EKG. Um, because if my concern for what we call the pre risk probability or my overall concern that they'd have something bad going on if it's more than just almost nothing, I'm probably going to add some sort of imaging to the treadmill, whether that be a stress echocardiogram or a nuclear stress test. So um, we're not doing very many treadmill tests alone these days just for, for the evaluation of chest pain. But I think in the right population, very low risk patient, normal EKG, and you're feeling pretty confident that this pain isn't coming from the heart, then I think it's a good test because that is the test with the lowest sensitivity, meaning about 30% of the time you're just going to get a false positive test anyway, maybe even a little bit more in women. So not a great test, but useful in the right population. I think that's how I would sum it up. So for the next group, let's say you're a little more concerned. They have higher risk, but they're still able to prove that they can walk on the treadmill briskly enough to get their heart rate up to that target level we're looking for. I think stress echocardiogram is a is a test. We probably do most commonly. And so, Doctor Vu, would you mind just I mean, that's a treadmill test still EKG is on. We're still looking at the EKG throughout. But then we add some additional, um, tools to look at the heart.

John Vu, MD: [00:07:49] Yeah, abswombolutely. So we still use the treadmill as a way of physiologically testing their heart. We look at their blood pressure and heart rate response. Those are all valid things to look at. But we add imaging this time. We add echocardiography which is ultrasound imaging. It's the same technology we would use to ultrasound a baby and the mother's wombs. It's completely safe. It's very easily done. We do it pre-exercise and we do it immediately after exercise. And we compare the pictures, uh, before they exercise with the pictures after. And we're looking for what we call wall motion abnormalities, you know, changes in their heart function, changes in parts of their heart. Those all correspond to certain anatomical regions in the heart. And they're fed by certain arteries, uh, in the heart that could potentially be blocked and be cause of their chest pain. Um, so as long as the pictures are good, uh, the stress echo adds a certain amount of sensitivity and specificity. And I say that, uh, most of the time, I agree with you that, uh, treadmill stress testing alone is not that much useful anymore because adding echocardiography really heightens the sensitivity specificity. It just makes it a much better test overall.

Matthew DeVane, DO FACC: [00:09:10] Yeah. So there's three things we're looking at. When I see somebody on treadmill we're looking at for symptoms. You know. So that's a key component is is there chest pain reproducible when they're exercising. That points toward the heart. We're still looking at the EKG to see if there's changes on the EKG that could suggest their artery is not getting enough blood flow to the heart. And now we've added this third component, which is the ultrasound imaging of the heart. So we're looking at the heart function before the exercise. We run them on the treadmill, lay them down, ultrasound the heart when it's still kind of maximally beating and pumping and doing all this thing. And we see if there are changes from before to after to suggest there's a blocked artery. So I think that test is sort of a sweet spot for most of our patients where we still think, hey, we got to make sure that you're safe, that the pain you're having is not related to any blockages in the arteries of the heart. So, um, yeah, stress echoes very useful. [00:10:04] Yeah. [00:10:04]

John Vu, MD: [00:10:04] Okay. Yeah. One thing I'd like to add is those are very quick to do. Uh, we can get those out in about 30, 40 minutes.

Matthew DeVane, DO FACC: [00:10:11] Stress echo is easy. There's no IV. There's no prep. Patient comes in with some hopefully comfortable walking shoes. We put them through their paces on the treadmill, get some images of the heart. Our technicians at John Muir Health are wonderful. They treat the patients well. They get us good pictures, and then the physician will be reading the test. And either, you know, if it's our own patient, we'll be talking with you about the results. If it's a. referral from a primary care physician will make sure they get the results and then figure out next steps. So if the test is completely normal and you have no symptoms and the heart function is good, we can go back to the again, the test isn't perfect, but we can say with pretty good confidence that the symptoms you're having are not heart related. If the test is positive, we've got a whole nother thing on our hands, which we can talk about. Well, let's just talk about now. So somebody comes in, they your chest pain you're having? I'm not quite sure. Is it your heart or not? We get the stress test done and now we've got a positive test. We don't need to get into the details of of, you know, all the treatment options, but what would you be telling your patient if they came to you and said, hey, I just had a positive stress echocardiogram. What would you do next?

John Vu, MD: [00:11:15] So I'd like to look at the details of the test. Obviously, how far they went in the test would be a good predictor of how good the test is. If they only made it three minutes, four minutes, their EKG changed dramatically, or their blood pressure had a significant change and they had wall motion changes. I'd say that is pretty strong test that you have disease, that we need to move on to the next level of testing, which is likely going to be an invasive coronary angiography, to look exactly where the blockage is. Now, if they did a test and they got, you know, uh, ten minutes on the treadmill and their EKG had some funky changes, but their pictures of their heart was completely normal, I'd say, well, that's probably a, uh, intrinsic problem with the treadmill itself, not necessarily of your heart. And that's why we did, uh, imaging, because it helped us sort of clarify if this was truly a, a positive study or not. And that would fall in sort of a false positive, uh, category. So I really look at, uh, how far they went, how they felt if they had no chest pain, and especially if the two parts of the test, um, you know, they, they, uh, they agree, then I think that's a much stronger test.

Matthew DeVane, DO FACC: [00:12:33] Yeah. Yeah, I kind of think of it as, uh, as I hopefully there's three results that come from a stress test. Either it's completely normal, like, okay, see you later. Call me if you need me. From a cardiology standpoint, um, it's very, very positive. And you're like, oh my gosh. Okay, we've now know that your chest pain is coming from the heart and you're going to need an angiogram or medications or whatever path that takes us along. And then there's that range of non-diagnostic tests where either your symptoms don't match up or the EKG and the echo don't match up, or this scenario just doesn't clinically make as much sense. So uh, moderate percent of the time you're going to get this non-diagnostic study where the cardiologist still may be a little unsure of what you have. And then depending on your overall risk, that may lead to an angiogram, just a 100%. Find out what you have, or it may lead to a different type of stress test called a nuclear stress test, which is kind of the next step up in our toolbox of stress testing. So nuclear stress testing, that kind of freaks people out because there's some radioactivity and this, that and the other. But a super safe test. And I know you're an expert at nuclear stress testing. Can you give us an overview, Doctor Vu, of what a nuclear stress test is and how a patient can expect to what their expectations can be?

John Vu, MD: [00:13:46] Yeah. So when we say nuclear, they get a little worried that it's radiation. I try to tell them, look, it's a potassium analog. It's something your body and your muscles need. It's absorbed. It's not going to radiate you. It's only last a few, uh, hours at the most. Uh, you're safe to sit next to anybody you want to afterwards. Uh, because they're worried about just the whole nuclear aspect of it. And I tell them that, you know, most likely we'll do the test the same way. Maybe it's a treadmill, or maybe you didn't do well on the treadmill. And we'll do a different way with the pharmacologic testing. But the imaging from nuclear is really, uh, much, uh, more, uh, comprehensive in that it actually looks at the muscle tissue and sees if there is good perfusion. And the correlate with that is if there's good perfusion, there's good blood flow to your heart and your arteries are open. So there are two sets of pictures. You get a resting set. And if the heart lights up all bright and even then we know your, uh, blood flow is normal. And then after exercise, we expect the same sort of image. Uh, the heart should light up as bright if it doesn't light up bright. Or there's certain parts of it that don't light up bright. It also corresponds to a, uh, artery that potentially is blocked. So, uh, aside from the physiologic testing of the treadmill, it also gives us an enhanced sort of image of what? Sort of what I call the, uh, you know, the roadmap could potentially sort of a heat map. Yeah.

Matthew DeVane, DO FACC: [00:15:15] And I think that the nice thing about the nuclear stress testing and the reason we use it so often as cardiologists is because it does offer us the option of not using the treadmill at all. So there's only two ways to stress your heart. For us, it's either a treadmill. Or it's with medication. And so the nuclear stress testing gives us that option to only use medications that stressor. So of course that does require an IV. Now where the other two types don't. But you just sit there and we give the medication stresses the heart out. And it's just like you're exercising. Actually, even maybe more, um, accurate is the most accurate, non-invasive stress test that we typically do at our cardiology office gives you unbelievable information. It does require the patients commit three plus hours at the office to get this test done because as you mentioned, Doctor Vu, there's a set of images at rest. And then there's a little break and then there's a second set of images. But it does give us absolutely beautiful images of the heart tells us if you've had older heart attacks, tells you if at risk for having new heart attacks, and it tells us with pretty good accuracy whether your chest pain is coming from your heart or not. So the nuclear stress test is a huge tool for us to help sort out how aggressive to be with people and whether or not they need medications and angiograms. So, um, yeah, I love it.

Carolyn Lacey, MD FACC: [00:16:38] I make sure to tell patients that it's going to be a long time that they're sitting there. Yeah, it's a lot of hurry up and wait. The testing in and of itself isn't that long, but it takes time to allow.

John Vu, MD: [00:16:50] We have to wait.

Carolyn Lacey, MD FACC: [00:16:51] The perfusion to happen and write in the medication injection. Now is a minute. It's a minute. It's quick.

John Vu, MD: [00:16:59] It's quick, it's quick.

Matthew DeVane, DO FACC: [00:17:00] And it's safe. And it's probably it gives us the most information out of any other tests because it gives us blood flow, gives us heart function and, um, just a beautiful, beautiful picture of the blood flow to the heart, which helps us assess the patients. That was a nice kind of a quick overview of what your doctor may be thinking when he or she orders a stress test. Fortunately, we have a lot of tools to choose from these days when checking the blood flow to your heart. If you need a stress test, don't panic. Just get it done and then work with your physician on what to do with the results. And once again, Doctor Vu, thank you so much for joining us, Doctor Lacey, and I really appreciate you being here. This is Doctor Matt DeVane and on behalf of my co-host, Doctor Carolyn Lacey and our partners at John Muir Health, we hope that you enjoyed this show and we really hope that you keep living heart smart.

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