Evo Terra (Host): Early coronary artery disease detection might just save your life or the life of someone you love. Good news, it's a lot easier today than ever before.

Host: Welcome to Doc Talk, presented by Montefiore St. Luke's Cornwall. I'm your host, Evo Terra. My guest today is Dr. John Tighe, Chairman of the Cardiac Catheterization Lab at Montefiore, St. Luke's Cornwall. Dr. Tighe, thanks for joining me here on Doc Talk.

John Tighe, MD: It's a pleasure to be here.

Evo Terra (Host): So, my family has a history of coronary artery disease. We die, our hearts fail eventually when we hit our 90s, so it's not too bad. But I got to tell you, doc, I've not heard of either CCTA or heart flow. Can you explain what each of those things is?

John Tighe, MD: Well, why don't we take a step back and talk about assessing coronary risk. When we talk about people, and this is something I see a lot, I have a lot of patients that come into my office with that very history. You know, they have a family history of heart disease and maybe they have high blood pressure or they have a high cholesterol. But they're not taking any medications and they feel pretty healthy and they're keeping physically active. And their question to me is, "Well, what does this mean to me? I have a family history. Well, how do I go about assessing risk?" Okay? So, what the bigger question is, is assessing cardiovascular risk, right? So in cardiac CT angiography, essentially what we're going to have is a tool that allows us to see the coronary arteries and what more or less looks like a stop-motion image of the heart arteries laying across the surface of the heart. The heart's a moving structure and conventional CT produces kind of a blurry image. So, we don't really get a good look at the coronary arteries. We can see where they are and we see where the heart is, but we don't get detail, anatomic detail that we would get from an invasive cardiac catheterization like we do in our laboratory here at Saint Lukes.

So, what we do, newer CT scanners have been devised that capture 64 slices, 128 slices, 256 slices of information all at the same time. They have detectors that capture images essentially that produce what looks like a stop-motion image of the heart with very high resolution. So, we can actually give an injection of IV dye through a peripheral IV. And we can fill the coronary arteries out with dye if we time it correctly, and we can actually see the inside of the arteries, which is what we see in the cath lab. But we can also see the walls of the coronary arteries and we can see the type, the composition and the characteristics of the plaques that are in the coronary arteries. So, it gives us the anatomy of the coronaries and in detail that you really can't get any other way. So, this is a very nice tool for us to actually elaborate the coronary arteries and give a patient an idea of what the amount of coronary artery disease that they may have

Host: Right. So, just to make sure I understand this properly, right? So instead of running a camera, if you can't even do that all the way through those coronary arteries, now you've got this method by taking a whole bunch of pictures at the same time that gives you that quick look at what the heart really looks like in great detail, right?

John Tighe, MD: Exactly.

Host: Excellent.

John Tighe, MD: It's a noninvasive way for us to be able to get the same information that conventionally we used to have to do back in the old days. And even today, when we were thinking about fixing coronary arteries with angioplasty by going through the leg or going through the wrist and invading the body to get this information. And in fact, we're getting more information from the CT scan than we're getting from conventional angiography because we're seeing the composition of the plaque, not just the inside of the arteries themselves.

Host: Got it, got it. All right. So, that's a good rundown. So, let's talk about that abbreviation, CCTA. What's that?

John Tighe, MD: So, that means a coronary CT angiography. So essentially, a CT angiogram, a computerized tomographic angiogram of the coronary arteries with angiographic dye.

Host: All right. And HeartFlow?

John Tighe, MD: HeartFlow is a technique that gives us more about the physiology of the coronary arteries. You know, when we're getting the anatomy, what we're getting from a CT angiogram essentially is an anatomic description. We're getting a picture of a coronary tree and we will see plaques in various locations if the patient has coronary disease. And some of these plaques may be relatively mild. Some of these plaques may be quite severe, obviously obstructive. And some of these plaques may be in an intermediate zone where the plaque looks like it could potentially be obstructive, and we don't know for sure.

Invasive angiography over the years has develop techniques for trying to answer the question of whether a plaque seen on a coronary angiogram is obstructive or not. In other words, when we do angiography, we're getting anatomy, but we're not really getting physiology. We're not really getting an understanding of what the flow characteristics are in any given location in a plaque where it looks like it might be obstructive, can't really tell. But over the last several decades, wires that can be passed down into the coronary arteries have allowed us to explain and to characterize flow down the coronary artery as a function of pressure across a blockage. So, it allows us to actually measure the drop in pressure that occurs across a blockage in a coronary artery and tells us, "Yes, this is a blockage. It's significant enough physiologically to cause the patient's symptoms."

Host: All right. So, I'm already itching to call my cardiologist right now and get this scheduled.

John Tighe, MD: Well, this invasive technique is called fractional flow reserve, FFR. So, this technique has been devised and it's been validated in invasive angiography. But with our CT scan angiogram, we didn't really have that same physiological correlate until the advent of this new technology called HeartFlow.

Heart Flow essentially is a deep learning algorithm and it allows us to take the angiogram that we take up the patient and run it through an AI program that was developed by this company. And it allows us to be able to build a model of the coronary arteries and look at flow and basically be able to produce an FFR measurement just like we can get in the cath lab, but without invading the patient. Again, a non-invasive technique that allows us to characterize flow down the coronary artery and gives us an idea of the physiology of that blockage. Is this blockage obstructive? Is it causing a problem with blood flow to the heart or not?

Host: So, non-invasive, does that mean no risk at all?

John Tighe, MD: Well, it doesn't mean no risk because anytime we're going to do any technique, even giving IV dye, there's the chance of allergic reaction. Radiation is something that we're talking much more about in cardiovascular medicine in general. CT scans are getting better in terms of the amount of radiation that you're exposed to, but a conventional CT scan can give a fair amount of radiation exposure, so can nuclear stress test unfortunately, too. The way we do CCTA is we time it to your cardiac cycle. And if done so correctly and with a good control of the patient's heart rate, at the time of the image acquisition, we can use about three to four times less radiation than we would normally use for a conventional CT or a nuclear stress test. So, we are reducing the risk of radiation exposure in making the test safer.

Host: So, this sounds fascinating. I'm curious from your perspective as a physician that has this tool available and you didn't have that tool available when you're thinking about these, how does this help you do your job more effectively?

John Tighe, MD: Well, for me, what I like is that it is a test that gives me all the information I really need in terms of managing the patient. I have a patient, getting back to your initial question, which is, "I have a family history of coronary artery disease. What do I need to do in order to know what my risk is?" Well, the CT scanner can allow me to take a picture without any dye, and it'll allow me to see the calcium if there's any calcium on the coronary arteries. Calcium on coronary arteries is a marker of mature plaque. If we see any calcium, it tells us that you've been working on this process for a while, likely decades, because it takes about 20 or 30 years for plaque to calcify. So, it tells us that plaque is already underfoot, heart disease is already present. And it gives us an idea of risk because we can stratify the amount of calcium that we see on the coronary artery as a function of risk.

So, I get with no dye, just a picture of your chest using the CT scan I get, "Okay. Yes, coronary disease is here." We have an idea of how much coronary disease is present and we have an idea of risk. If there are symptoms going on or if we have a lot of calcium, we can use a dye study, this CCTA test to tell us whether or not there's a problem with obstruction of flow to the anatomy. If we have questions about that anatomy and we think maybe there's a blockage here that's important, we can apply the HeartFlow deep learning algorithm to the dataset, and that'll tell us whether or not there's a physiologic blockage. So, we get diagnosis, we get extent, we get the anatomy, and we get the physiology of coronary artery disease in a single study.

Host: I mean, it sounds to me as a layperson looking at this, it's almost like you have the ability to-- and this is going to sound weird, people-- hold someone's heart in your hand and examine all of the intricacies ins and out of it and say, "This is what's really right and wrong." Am I overselling that?

John Tighe, MD: Well, I think when it comes to coronary artery disease risk, yeah, I think that's actually nice simple way to explain it because you're getting all of this data. And you're getting it all with one study with a small amount of radiation exposure and a small amount of IV contrast. You're getting quite a bit of information for that time spent. And I think because of that and because we have such a powerful tool, the performing conventional coronary angiography for evaluating chest pain or for evaluating abnormal stress tests is starting to fall by the wayside. We're starting to move patients more towards doing CT angiography as a means of figuring out which patients are the patients that would really benefit from having a stent or which patients would be best managed medically. We can instead of taking a patient and deciding, "Well, this patient needs a stent, or this patient doesn't need a stent," we can do a CT angiogram, a CTA with HeartFlow. And we can say, "This patient does not need to go to the cath lab to get a stent put in, needs to take medications, needs to lower their cholesterol, needs to change their lifestyle, take aspirin" or "This patient has a physiologic blockage in an important coronary artery where they would benefit from having a stent placed." So, we can actually reduce the number of catheterizations that are being done purely for diagnostic purposes, invasive procedures that come with some risk and reserve those invasive procedures for the patients who would truly benefit, the patients who need to be revascularized.

Host: Like I said earlier, I want to call my cardiologist right now and schedule one of these, but maybe that's not the best idea. Rather than asking you who's the best candidate for this, who's not a good candidate to have this performed?

John Tighe, MD: Well, I think that, when it comes to HeartFlow, there are a few exclusions. Coronary stents are not really validated with HeartFlow. So although we can image patients with conventional CTTA, we can still do the procedure, we can get information from the CT angiogram. And we can actually see inside most coronary stents, as long as they're of a certain size. We can't use the deep learning algorithm. It's not been validated in terms of explaining flow down those coronary arterys that have been stented in the past. And similarly, patients who've had bypass grafts, from coronary bypass surgery, that's another group of patients where we don't have sufficient data to be able to say that the results that we're getting are as accurate as we'd like them to be. So, aside from that, patients who have coronary arteries who have never had those procedures performed are the ones that we have the most validated for.

Host: And how do the insurance companies feel about these new procedures? Are they paying for it?

John Tighe, MD: Yeah. It seems to be that they're recognizing the power of this test. And because of its increasing use, they are paying for this procedure to be done.

Host: That's great news, Dr. Tighe. Thank you. Again, eye-opening, amazing advances in medicine. I appreciate you sharing it with us here on the program.

John Tighe, MD: It was a pleasure, Evo. Thanks for your time. And thanks for listening.

Host: Once again, that was Dr. John Tighe, Chairman of the Cardiac Catheterization Lab at Montefiore St. Luke's Cornwall. Thanks for listening to this episode of Doc Talk, presented by Montefiore St. Luke's Cornwall. For more information, please visit montefioreslc.org. That's M-O-N-T-E-F-I-O-R-E-S-L-C.org. And remember to rate and review the Doc Talk podcast if you found this episode helpful, and please share it on your social media channels. And thanks once again for listening to Doc Talk presented by Montefiore St. Luke's Cornwall. Hoping your health is good health. I'm Evo Terra.