Chapters Transcript Video Coronary Physiology Ultrasound Dr. Justin Heizer reviews early studies and evidence for coronary physiologic testing. All right, great talks. Thank you all. Um So my name for those of you that don't know me. My name is Justin Heiser. I'm one of the uh interventional cardiologists that's been here the last couple of years. Um starting to take on more com complex cases, be more involved with the chip team and the heart team approach as um they alluded to. Um So I know we're moving a little behind but um so I'll try to run through this pretty quickly. Um But touching the high points. Ok. So we'll be talking about coronary physiology and intra coronary imaging. Um These are two things that have become very important to, you know, what I do on a daily basis and I'm, I'm using them basically on pretty much every case that I'm doing one or the other. Um And let's see what, let's keep, keep going. This. Yeah, the green. There it goes. All right. Um So the objectives, we first talk about the early studies of coronary physiology. Um and then the recent developments and how it changes our practice and then we'll go over uh inter coronary imaging and different techniques and how we use it in PC I. So, first about coronary flow and, and flow reserve. Um usually in the normal coronary artery that has no disease. Uh The epicardial coronary artery does not account for much of the resistance of the system. And it's usually the smaller arteries that you can't even see on the angiogram. On the angiogram, you can only see 20% of the actual um blood vess blood vessels there in the heart. So, um you'll see, however, in a stenosis on the left, um there are a bunch of different things that basically contribute to the um to um how the stenosis uh affects flow in the coronary. There's the angle, um there's the length of the disease segment, there's also the length of the most severe disease segment. And there's other factors too that um eventually as the stenosis gets worse, it will affect the flow, create turbulent flow, sheer forces and those sorts of things. Um And so, considering these factors, this is how the um fractional flow reserve was developed, which is basically the maxim cardial blood flow in the presence of a stenosis divided by the expected normal blood flow without the stenosis. Um And that can be equated to essentially the PD over the P A, which is the distal pressure over the aortic pressure. Um And so, here's a sort of a schematic representation of um an FFR measurement. Um initially here, you'll see the resting pressures. Um You have the aortic pressure, which is the red one and the green one is the coronary pressure distally. And you'll see how after the administration of Dennis, there's a, a dramatic effect in the flow um in that distal coronary bed. Uh And so that's how, that's how these initial studies on uh fractional flow reserve were sort of developed and they created sort of a cut off of about 0.75 was a significant FFR and there was a gray zone of 0.75 to 0.8. And since that time, um 0.8 has really been the cut off for significance of an FFR measurement. Ok. Uh So we have a lot of different ways of checking physiology. Now, we have CT scans that can do it. Um We have the FFR but we also have non hyperemic ratios which we use regularly. Now in the Cath lab, um including the Ifr which is the instant instantaneous freeway ratio. There's also the RFRDFRV PR. We don't have to go into all of those, but there, there are a lot of, of different um different resources available for that. We'll talk a bit about the initial um studies that were done for FFR and Ifr, on the right, you'll see the fame and fame two studies and then on the left for Ifrifr sweetheart and defined Flair for the FFR studies, F AM E and F AM E two. I won't go into the details on these, you could see what's up on here. But um essentially F AM E was looking mainly at patients with multivessel coronary disease. And it was to determine if FFR guidance led to better outcomes for these patients. And ultimately, what they found was that um the number of stents in the FFR group was much lower than those who had angiographic guid guided um coronary intervention. Basically 1.9 stents versus 2.7. So you're dec decreasing the need for resources um and potentially offering more um more uh efficient care for these patients. OK. Uh And then FA E two was looking more at patients with chronic stable angina rather than multivessel disease. And using FFR for um for guiding PC I versus angiography in these patients. And this showed that FFR guided PC is was superior to optimal medical therapy uh in patients with chronic stable angina. And this is uh fame two results essentially looking at the primary endpoint of mace uh PC I compared to medical therapy and FFR guided PC I. So, um basically, from both of these studies, FFR may help avoid unnecessary Reva ization for multi vessel disease and it's also more cost-effective. And then for FA E two, FFR guided PC I decreases the need for Reva improve symptoms in patients with chronic angina. Here's a representation of the um the non hyperemic measurements that we use. Essentially, they're all measured during this free wave period, basically where there's no background interference and where the um microvascular impact is the lowest. And, and so that's, that's the advantage of measuring these ratios. Ifr is throughout that whole free wave period. RFR you can see is at the lowest point um of the PDPDP A ratio. And then we had all these IFR trials that came out sort of in the early 20 tens uh defined flare and IFR sweetheart were the largest by far, about 12 10, uh 1000 to 1200 patients per study and defined flare. Essentially, both of them were looking at the same thing, basically intermediate re uh lesions in patients who have chronic stable angina or A CS. And if they had a CS, the FFR was not done on the um the culprit lesion obviously, but on the um the non corporate lesions. And so the impact of both of these is that Ifr guided PC I was um shown to lead to similar outcomes and with better patient experience compared to the FFR, because you're not giving a dentist scene and a dentist scene can be quite uncomfortable for the majority of patients. And in both of these studies, that was about 30% of patients, we have, we now have um five year results of the Ifr Sweetheart uh trials. So FFR has 10 to 15 year results. And so it's been widely proven, but we're now starting to see that IFR uh is also proven over the long term to be effective and just a bit about using Ifr in the left Maine and proximity. It may not be quite as effective or accurate and there can be a difference in up to 20 to 30% of cases. Um So Ifr is not typically my immediate go to, if I have a left Maine, I have used it in the proximal led, but I did have one patient where they had like a 50% lesion. This was just about a year ago. Um And it, it really wasn't that bad ifr was like one and then about six months later, they ended up having a 90% proximal led. Um So it's something to consider uh fame three, also something published within the last uh couple of years. Uh Basically looking at patients with um FFR guided PC I versus cabbage. Um And essentially, there was no difference in these patients with multi vessel disease uh as far as outcomes. However, you can kind of see on the graph that, that it may be leaning in favor of, of cabbage for a lot of these patients. Keep in mind that in this study, about 30% of the patients that did have diabetes and diabetes is, is one of the main factors that would, would push us more towards surgery in the. And here's a, um here's also a, a subgroup analysis which shows that you can see in a diabetic group, they definitely benefit more from, from bypass. And um in low syntax, there may actually be a benefit of PC I compared to cabbage in patients with multivessel disease based on this study. Flower M I we're not going to go into um but physiology who do we, who do we use it on? When do we use it where um for stable angina, intermediate lesions and no documented ischemia, there's a class one, a recommendation for that. So if, if we're going to use a stent on a patient with an intermediate lesion, we we really need to document ischemia and and that has to be present. Um So all the major guidelines recommend that you may also use it multivessel disease where functional studies can't be as sensitive. So with stress tests, especially spect, you may see balanced ischemia and therefore, the stress test may be, may be negative or um may be mildly uh risky. Um So that might be a good, a good time to use it uh for stemi or in sty patients for non corporate lesions, multiple sequential lesions ifr is especially useful in this in this sense because you can do a pullback and see which stenoses are potentially causing the um the flow limitation. And then also post PC I assessment, we'll talk about that briefly over the next coming slides and then uh there's other uses for it as well. OK. So we'll do a quick case. Um This is fairly recent, basically a a patient who is in their low seventies. Um younger seventies very functional coming in with an NSTEMI unstable angina low-level troponin and uh without active chest pain, we took her for angiogram and found that there's an intermediate lesion in the L AD which you can see proximal, maybe 40% mid more tubular, 40%. So, yeah, maybe, maybe not significant, probably not the cause for the inte you can see the circ lesion at the top, which is over 90% which is the culprit lesion. But it's also noted that that's sort of there's a couple bifurcations at that lesion and, and there's disease in that branch next to it as well. So it could potentially be a complex intervention, you could lose some side branches, which uh if you just outright stent that it might not be as much of a benefit to the patient and there's an RC A lesion as well. So what I I decided to do on this patient was do ifr of the L AD to see if that's significant. And as you can see across the, the mid lesion, there was a significant step up. Uh The ifr I think measured at 0.840 0.85. And so we're referring that patient to bypass. Um Another thing to consider in this patient, they also had severe uh aortic insufficiency. So I think you do have to take the patient's functionality. There are other factors into account when you're when you're deciding what treatments are best for patients. So now we move on to ultrasound. Um whenever I think of ultrasound or echo, it reminds me of um one of my mentors back at VCU, Doctor Walter Paulson, who um equated ultrasound sort of um Plato's allegory of the cave where only in the truth, only do in the shadows, do we see truth? So I thought that was interesting and I, I think about that. Um So inter coronary imaging, we have the option of IVIS or OCT uh IVIS you can see on the top left. Uh It, it does give you clear images but doesn't have quite as good of a resolution as the OCT as you can see on the bottom. Um Basically the uh schemata on the right tells you you're looking at lumen, you should also see intima media and an adventitia that area where you see the dark area meet the very bright echo bright area is where the media meets the adventitia, also the um external elastic lamina. And that's sort of where we uh size our stents based on one of the early pioneers in IVS and um Inter Coronary imaging was uh Antonio Colombo in Italy. And um basically published the first studies looking at IVIS optimized PC I and showing that IVIS improved um minimal stent area by significant amounts up to 40 or 50% and it also decreased re stenosis rates. So, uh that really is has led to a big change in our field. Um And then on the right, it is another study of a meta analysis of all the randomized trials at that time, looking at IVIS and um how it's improved six month re Reva rates um need for repeat re reintervention at one year and also mace down at the bottom. So what are we looking at when we're using IVIS? Uh pre PC I uh one main thing is uh plaque, morphology and composition. And you can see on these, on these pictures up here. See if that. Well, I don't think this is working, but um top left, you can see that's a uh basically a fatty plaque. And next to it is more of a fibrous plaque. It's a little brighter closer to the how the adventis looks to the right of that is deep calcium to and all the way to the right is more superficial calcium. On the bottom left is circumferential calcium to the right of that is a very severe, more fibro fatty plaque. And then next to that, you can see there's a um fatty pool or a lipid rich pool, which is something that actually puts patients at risk of uh plaque rupture or unstable plaque. And then to the right is a plaque rupture. So with good IVIS imaging, you can identify all these things and it and it can impact how you treat a patient. Um IVIS is also particularly useful in left maine um and lesion preparation. So th this is how we use IVIS pre PC I for lesion preparation. Uh we measure out the, the area basically at the proximal edge of the lesion and the distal edge. And you want to do that based on the external elastic lamina. In most cases, uh sometimes you have to use the lesion itself. Uh but you want to put a stent within an area of stenosis where on the edges, there's less than 50% stenosis or reduced calcium. We we just had a great grand rounds about this as well. Actually, um oct, you can see it's a little harder to see the external lasic lamina if you're not used to using it, but it's a little bit beyond uh that, that bright area where sort of the bright then makes it meets the dark. Here's an example of optimal lesion preparation using oct. You can see the uh there was, there was heavy calcification and you can see the actual cracks in the calcium that were created by using rotational Atherectomy. And this really is something. If we're using Atherectomy, we should try to visualize this before we put any stents in to make sure we have modified the plaque or if we're using Lithotripsy. OK. Ives post PC I has been also shown to improve outcomes um and it can help us to assess for stent failure or problems with the stent. You could see thrombus within the stent dissection at the leading edge or the distal edge uh malas position under expansion. And there's representations of that on this slide, the top left labeled A is under expansion to the right. And on the bottom also is where there's malas position. So both of these factors are high risk for um early and late stent closure or instant re stenosis. And so they're, they're quite important. Um IVIS may also be used for pseudo side branch encroachment if you stent over a branch. Uh and you need to assess that a little bit further. Oftentimes a a branch may look stenosed at the ostium after you've stented across it. But it's, it's, it can be affected by spasm. So if you could get a wire in there and assess it with IVIS and see that there's no stenosis that's helpful. More often I I would use ifr for this sort of thing because it, it can sometimes be hard to get the IVIS through, you know, the stent struts and that sort of thing. Also post PC I. For the left main bifurcation, there are a set of sort of goals that you should have. If you're doing a left main PC I, you want to get about six millimeters or more in the estimate the L ad in the circ about five millimeters and then in the left main itself, eight millimeters or 8.8. Depends on the studies you look at uh in any lesion, if you're doing post post PC I IVIS really, I try to shoot for at least five millimeters squared of area. Uh And I think that's a pretty good cut off for the drug alluding stents that we use, that we use today. OK. And here's a recent uh this was published within the last month or so. It's best prac best practice summary for the use of intravascular inter coronary imaging and here's our conclusions. So for FFR or Ifr, um FFR guided PC I has been widely validated and studied Ifr also has become more widely validated and we're having longer term data as well. Um For in intravascular imaging, IVS and OCT can both be used as good diagnostic tools and can be used during and after PC I to optimize our outcomes for patients. All right. Thank you, Justin. That was a fantastic talk. I think um a couple of points from my standpoint, I know we all love data and this data that you're getting for the patients will not only help you guys with your interventions, but I can just tell you with me, it's helped me out a lot that road mapping that you do took one case where I wouldn't necessarily have grafted an additional vessel based on angiography alone. But that road map you did where you prove the pressure was there. I did after an additional vessel. And so making those kind of changes, especially in our case where someone's going to go to the operating room and have the risk of Stronomy and bypass. I, I think it's, I think it's a game changer. I guess my question for you is who for, for patients that are going to go to surgery? Um, or that you, that you're not planning on PC, I, what makes the decision to do that? Sophisticated mapping versus not? Is it sort of the gestalt you have when you look at the NGO or I think, I think it's considering the patient more than anything. Um And really the, the functionality also, you know, if, if they have two or three lesions, sort of the locations of the lesions, um especially if there's any L AD involvement. Um It's not, it's not uncommon that I'll, that I'll test the led on patients if there's an a culprit lesion in another vessel. And I see that there's something significant over there proximal led in particular. So I was more concerned about the proximal in that one patient, but it ended up being the mid that was flow limiting. So yeah, it's gonna be the angiographically indeterminate lesion. And you want to know if A Lima to L AD is going to improve their survival versus branch vessel disease where you're gonna be like, OK, I'm gonna treat that percutaneously. And then there's the uh a concept of geographic my and how you can stent the vessel. I think you got a great result. And you're doing some of these studies and you realize that there are angiographically hidden lesions that were missing. And we think our outcomes can be maybe a little bit closer to surgical outcomes if we do that more regularly. And another thing to consider is yeah, calcium and com complexity of the lesion and tortuosity. Actually, all of these studies that I mentioned those were exclusions for all of those studies. So if you have heavy calcium or tortuous vessels, um they're excluded from the FFRFFR sort of studies. So we don't know as much about those patients, you know, what they would benefit from more and they often carry higher risk probably both for, for bypass and for PC I particularly I where the guidelines haven't kept up with the data. Would you submit that? Um as some people do that IVIS should be routine for every procedure. I, I would say that um it, it shouldn't be mandated um necessarily, but I think that it, I, I don't, I don't know how the guidelines would have would address this, but um I, I definitely see that there's a huge impact, you know, on using ibis and optimizing oftentimes. Uh if I'm not using it before putting a stent in, I might use it afterwards, it depending on the location and, and see that, you know, I didn't quite size the stent, right? And then sometimes you are surprised about how the, the difference between what you find angiographically versus what you see on the Ibis is so drastic, you know? So, I don't know that it should necessarily be mandated because, you know, that sort of dictates what we do in the Cath Lab a little too much. Probably. What do you, I think there would be people who would argue it's probably best practices. We don't all do it. I don't, I don't do it 100% of the time. I try to do it most of the time. Yeah, same here. I would say, like, 90% of the time. Published October 17, 2023 Created by Related Presenters Justin Heizer, M.D. Sentara Cardiology Specialists View full profile
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