Prakash Chandran (Host): The computed tomography or CT program at Baylor Scott & White Heart and Vascular Hospital Dallas was awarded Gold Seal Accreditation for imaging services, quality and patient safety by the American College of Radiology. With the advanced CT technology of a dual-detector, dual-source 384-slice scanner, imaging physicians on the medical staff can obtain images of the body that freeze motion without asking patients to hold their breath, saving time and expediting treatment decisions.

Host: Here with us to discuss is Dr. Jeff Schussler, Chief Medical Officer on the medical staff at Baylor Scott & White Heart and Vascular Hospital Dallas.

Welcome to HeartSpeak, a podcast brought to you by Baylor Scott & White Heart and Vascular Hospital Dallas and Fort Worth, joint ownership with physicians. My name is Prakash Chandran. So Dr. Schussler, thank you so much for joining us today. I really appreciate your time. I wanted to get started with the basics. Can you tell us what CT is used for in cardiac imaging these days?

Dr. Jeff Schussler: Well, thanks for having me. Sure, happy to. CT scans have been around for a long time. Most people have had chest CTs, CTs of other parts of their body. Up until about 20 years ago, CTs weren't really fast enough to image a beating structure. The heart is obviously moving all the time, we want it to, but none of the scans were fast enough to freeze the images enough where we could see the smaller structures. So, this is actually a way for us to image some of these very small portions of the heart, including the valves, the arteries, and some of the other structures where we hadn't been able to see them as well before.

Host: Yeah. That's awesome. And I know that there are various different types of cardiac CT imaging tests. Can you kind of unpack those for us and tell us their purpose?

Dr. Jeff Schussler: in the past, we'd had to do things like stress tests or invasive tests like heart catheterization. But nowadays, a lot of times we don't have to do anything invasive to get really accurate information that previously we couldn't.

Host: Okay. Awesome. So, let's talk about some of the different ones. I know there's the, you know, CT angiogram, there's calcium score screening and I know there's different modalities based on what you have. Can you talk about maybe the most popular ones and when you would use them?

Dr. Jeff Schussler: The two biggest, at least that I'm involved in, are calcium score and CT coronary angiogram. And it very easily breaks down to one is a screening test looking for the presence or absence of early plaque, and that's a calcium score. And the big difference between that and a CT angiogram is the use of contrast. So for example, if you're a 50-year-old man, you have risk factors for coronary disease, like a first-degree relative that has heart disease or diabetes or smoking, and we'd like to know if it's a good idea to be on treatment like statin therapy. You can get an $80 screening test, I think that's roughly what it costs. And without an IV or without contrast, with a very, very short breath hold in a few seconds, they can scan your heart and look for early, premature, asymptomatic plaque, and that's a calcium score.

Host: Got it. And from what I understand, you know, the calcium builds over time. So, trying to get in early and get this calcium score before it becomes a blockage is pretty important.

Dr. Jeff Schussler: It's very helpful. Previously, you know, people are asking, "Well, am I at risk?" That's one of the big central questions I get asked all the time, is "I've got theoretical history, what should I be doing to protect myself?" And it's very helpful to know that you actually have the process versus guessing whether or not you have the process.

So even diabetics, people who are high risk, you don't always know that you're making plaque in your arteries. If you have a scan that proves that you have the process, it makes it a lot more concrete as far as what you should be doing. For example, anybody who has coronary plaque should be on statins if they can tolerate them. And knowing that you're not just taking this medication for a theoretical reason really helps people feel comfortable about being on these medicines.

Host: Yeah, it's kind of like establishing a baseline. And you kind of gave the example of a 50-year-old man. But for example, I just turned 41 and it's something that I've been recommended a number of times because my grandfather died at 50 years old of a cardiac event. And so, I think this is something people are proactively doing more and more. Is that correct?

Dr. Jeff Schussler: Yeah, they've become very popular, especially now that the price has come down. You know, back, gosh, 15, 20 years ago, it's several thousand dollars to get even a screening calcium score. And to have it be under a hundred dollars is really remarkable as far as bang for the buck information that we get. It's phenomenal for a, you know, cost versus benefit. But you're right, you know, there are people who I meet when they have their first heart attack and we say, "Gee, it'd really be a good idea to get you on medicines." But it would've been even better if somehow, 20 years prior, we'd say, "There is a potential for you to have a heart attack in the future, let's get you on medicines now and maybe change the course of your future." And that's the way I look at these calcium scores. People who have a very theoretical understanding of what the risk may be, it becomes more of an actual, "Hey, I am in that bullseye as far as potential problems in the future."

Host: Yeah. Okay. So, let's talk a little bit about the second most common one that you do, the CT angiogram. How does that differ from the calcium score of screening?

Dr. Jeff Schussler: So, the calcium score, they're both the same machine first of all, it's a CAT scan. The CT angiogram is actually a test where it looks for both calcific or hardened plaque, like the calcium score, but also soft plaque in the arteries. And calcium scores can tell you if you have plaque, but they can't tell you if that plaque is blocking the flow of blood, but CT angiograms can. So, as opposed to calcium score, which is a screening test for people without symptoms, this is really used for people who are having symptoms. So for example, let's take the same 50-year-old man having chest pain when they walk down the block, but not really clear if this is something that warrants an invasive test like a cardiac cath.

A lot of people these days, instead of doing stress tests, which are good but not great, they're wrong about 20% of the time; both false negative meaning they tell you something is not there and it is, or false positive meaning something is concerning, but it's really not there. CT angiograms actually look at the arteries directly. And so, based on the CT angiogram, we can say, "Hey, you have no plaque" or "Hey, you've got plaque, but it's not really the cause of your symptoms." Or in some cases, "You've got plaque, it's the cause of your symptoms, and we can tell you where it is, how bad it is," and it also helps us guide us as far as if you needed an invasive test where you might benefit from having things like a stent or a surgery.

Host: Yeah. Okay. That makes a lot of sense. So, the CT angiogram, to be clear, is like if people are experiencing symptoms, it could be shortness of breath or a little bit of chest pain, they would come in and kind of know in a more definitive sense with a CT angiogram.

Dr. Jeff Schussler: Yeah, it's a direct look at the heart arteries. For all intents and purposes, it's a non-invasive heart cath, which is remarkable. Because again, you know, if you go back 10, 15 years, we really didn't have an equivalent. You either had a non-invasive stress test, which was pretty good, but not great or you had a fully invasive heart cath, which is very, very accurate, but does come with some intrinsic risk. And there wasn't really a middle ground that was as accurate as a heart cath, but not necessarily as risky. And again, I don't want to scare anybody. Heart caths are a little bit risky, but not unsafe. But anything you don't need to do that's invasive is good, especially if there's another way of getting the same information.

Host: Okay. That's very helpful. Now, I know that this is probably less common, but I have also heard of a fractional flow reserve CT. Is this something that you can speak to?

Dr. Jeff Schussler: Sure. just a little bit of background, in the cath lab, there are people who have heart caths where we see blockages and we're sort of on the fence. We can't quite tell visually if they're severe enough that a stent would benefit them or not severe enough where they just need medicines. There hasn't up until a few years ago been an equivalent physiologic type test for CT. We could see the blockages and we say, "Well, I think that that's causing your symptoms," but there wasn't really this physiologic equivalent. And within the last five to six years, there's been an advance using computer technology, that actually the mathematics are beyond me, where they look and analyze both the flow of the blood as well as the angiogram itself and can give you an estimation if whether or not the blockage you see is really necessarily causing a reduction in the flow of blood. It's not perfect either, but it is an additive way for us to get additional information about the heart arteries and their blockages.

Host: Okay. Understood. So, you know, when I think about the benefit for patients, you know, obviously, there is the calcium score screening, which really establishes a baseline without you having symptoms, and that's just good about being proactive with your health; the CT angiogram and then, just kind of that additive that we just talked about is really about identifying that flow, if you're expressing symptoms, what you should do about it. Could you talk a little bit about the benefit for a referring provider, right? Like, we understand the patient benefits, but for that referring provider, unpack that for us a little bit.

Dr. Jeff Schussler: Sure. Well, depending on the test that you're talking about, there's different referral strategies. So the screening test, for example, interestingly for a calcium score, it's one of the few tests that patients can actually request themselves. I always actually recommend that most testing be done through a physician because, even if you get a test done, the information that comes back to you, you have to be able to do something with it. And so, it's always best if there's a physician sort of driving the ship as far as guiding therapy. But it is a test that can be ordered from a patient's perspective. But most of it comes to us from physicians who want to know more about their patient's risk.

CT angiograms, for example, really need to come from a referring physician for the most part. And it doesn't always have to be a cardiologist, although a lot of the tests are driven by cardiologists who want to get more information about whether or not their patients have blockage and whether they need something further done. But even, you know, general medicine doctors, internists, family practice, we get a lot of referrals from doctors who they aren't even sure if the symptoms are cardiac and they'd like some more information about whether their patients need to be referred to a cardiologist, for example. And so, they send them for these tests and say, "Oh, you know what? Your arteries are wide open. You've got no plaque. You don't need to see a cardiologist," or "Hey, you've got some plaque, but it's not that bad." And then, sometimes they refer to cardiology and sometimes they feel comfortable taking care of this on their own, where they can put them on statins, treat them medically. There are people who have potentially severe blockages, and those usually get referred to cardiologists once that information's back.

Host: Yeah, it's kind of clarity in the decision-making, I guess, for the most part. And like you said, it's always good to have that physician leading or, I guess, steering the ship to either provide clarity on what's going on to the patient or just knowing when to refer them to a cardiologist. Tell me when should a provider think about referring a patient to a specialty center for a cardiac CT imaging study?

Dr. Jeff Schussler: So, the screening part of it's actually easy. We get a ton of referrals for calcium scoring from a lot of different physicians and even others that are not necessarily traditional primary care. But you know, they've seen them on TV or they've seen something online and they'd like to get one done and whoever's taking care of them, whether that's their obstetrician, gynecologist, family practice, they facilitate getting a screening test.

The other group, the one that's more at risk, is those people who are having concerning symptoms. And symptoms, there's a wide variety of ways that people present with what might be heart disease, and the classic is obviously chest pain. People who are having symptoms when they're walking down the block, they get pressure or burning or aching in their chest, nauseated, sweaty, things like that. We're not talking about I'm-having-a-heart-attack symptoms, but we're talking about worrisome symptoms with exercise. Those are the kind of things that most doctors at least know, for the most part, when to send to a cardiologist for further evaluation. But symptoms come in a lot of varieties. And so, sometimes people have jaw pain or chest pain or back pain that is not traditionally thought of as cardiac or coronary. And so, sometimes they need some clarity and, imaging can help decide whether or not that referral really needs to be made.

Host: So just before we close, one of the things that I'm curious about is just the evolution of, I guess, the CT imaging technology, one of the things that you said is that before it may have been cost-prohibitive to do some of these scans or tests. And now, it's obviously more accessible and I imagine that the technology's evolving even more than that. Can you share a little bit more about what you're excited by when it comes to CT imaging?

Dr. Jeff Schussler: Sure. So, I've been doing this for the better part of 20 years. And honestly, the technology itself, every year basically, there's the newest, latest, and greatest. But when we first started doing this, we had scanners that were essentially 16 slices. Now, the slice thickness is how big of an area you can scan in every cycle of the CT scanner. And so with a very, very small amount of, you know, real estate, you had to scan multiple layers through a beating heart, and it was very hard to get good, crisp, clean images. The next step was 64-slice, 128. We've got a 384-slice scanner. There are bigger, faster scanners out there coming out every day. And it allows you to scan people with higher heart rates, with very, very short or no breath holds, and with really, really good submillimetric clarity. When we do a heart cath, we can see it's like 0.4 millimeters in resolution and you can get pretty much the same type of resolution now with CT. Whereas 20 years ago, you obviously couldn't. So, the actual physical resolution has become tremendous.

The next part of it is the actual software side. And although, you know, we touched base on it a little bit as far as things like additional software evaluation of narrowings or stenosis, up until recently, it was me looking at it with my eyes saying, "I think that there's a blockage," we have this added layer of software that can give you additional information about the physiology. And the next great frontier is artificial intelligence. And that's not just a buzzword, but they are actually working on software that can help interpret these angiograms. And the holy grail is obviously figuring out ways to predict the future. So, looking at plaque and saying, "Well, it's not that bad right now, but it looks like in the future it's going to cause a problem." We're not there yet. But every time I turn around, there's another paper looking at generative AI trying to interpret these scans and help us make good decisions.

Host: Yeah, it's pretty amazing. I mean, just with the sheer volume of imaging that's being done, that provides basically food for training the model that can then identify things and basically forecast how things will go based on blockage patterns. So, it's just so fascinating kind of the time that we live in.

Dr. Jeff Schussler: Oh, yeah, it's crazy what's going on out there.

Host: Absolutely. Thank you so much for your time today. We really appreciate it.

Dr. Jeff Schussler: Absolutely. Thank you for having me.

Host: That was Dr. Jeff Schussler, Chief Medical Officer on the medical staff at Baylor Scott & White Heart and Vascular Hospital Dallas. To refer to the Advanced Imaging Center at Baylor Scott & White Heart and Vascular Hospital Dallas, you can call 214-820-0160. Thanks for listening to HeartSpeak, a podcast by Baylor Scott & White Heart and Vascular Hospital in Dallas and Fort Worth.

If you found this episode to be helpful, please share it on your social channels and be sure to check out the entire podcast library for topics of interest to you. My name is Prakash Chandran. Thank you so much for listening. And until next time, stay well.

Baylor Scott & White Heart and Vascular Hospital Dallas and Fort Worth, joint ownership with physicians.