Dr. Mitchell describes the principals and clinical review of optical coherence tomography (OCT) and how imaging w/ IVUS or OCT improves long-term outcomes.
Hey guys, um, hey everyone, thanks for coming this morning and welcome. I'm Doctor Brian Mitchell. I'm one of the interventional cardiologists here, and I have the pleasure today to talk to you guys about intracoronary optical coherence tomography, um, and today the gonna really focus on the evidence and clinical applications. I mentioned not to be redundant in coronary because if you're someone that's new and, and researching OCT, let's say for example, you're a medical student that's very interested in cardiology, not pointing your fingers at anyone, and you get really confused at the images you Google, you're probably looking inside of an eyeball, so just be aware of that. I was not. Um, so we're going to talk about coronary. OCT. OK, so I have no disclosures. So, um, we're gonna talk a little bit about, and, and hopefully, uh, this is gonna be a pretty broad overview and, uh, you really touch on a lot of things, uh, everywhere from really the beginning and principles of OCT all the way to some evidence and then, uh, some really interesting future direction. So, I know some of you people have probably, uh, used OCT before and may be very facile with it, but others that are listening may not be. So we'll try to cover everything, keep everyone interested. So, uh, first off, um, you know, why do we care about intra coronary imaging? Well, as I'll discuss later on, and as many of you well know, that visual estimation of the luminal dimensions with angiography is often inaccurate, and time and time again, um, it's been proven that intracoronary imaging is, is beneficial. Um, not only can, uh, coronary angiography by visual estimation give a little information on plaque morphology, atherosclerotic burden, um, things like this, but also when you're assessing your stent post PCI, um, that's very insensitive, of course, as well. So you, you know, things like, uh, stent expansion, stent, um, acquisition is, is very difficult to see with just your naked eye. And as, uh, we'll talk about intravascular imaging, whether it be OCT, II, or both, improves, uh, long-term outcomes. And this is from, uh, Greg Stone's, uh, 2023 big, uh, you know, the, the live network meta analysis that showed intravascular imaging guidance versus angiography guidance in PCI really, I mean, just kind of across the board, reduced cardiac death, target lesion failure, MI, stent thrombosis, and that was a really robust, um. Inclusion of 20 randomized trials and over 12,000 randomized patients. So, um, based on that, there, it's um a 2B in, you know, the 2021 guidelines, but for. For the use of intravascular imaging for complex lesions is a 1A currently based on the ACCHA Sky guidelines. So, there's evidence to support this, that, that imaging in general is a really good thing to do. That's why we should use it. It's good for our patients. It's 1A for complex lesions. It's guideline directed. Um, and, uh, we'll talk a little bit more about OCT now. So. Won't dive too much into the physics of it, but it's essentially an optical analog of ibis that uses near infrared light instead of sound, and so you get these really high resolution cross-sectional images of the coronary artery, and if you think about it, you're getting a lot of resolution because of this, because of the speed of light, but that's also at the expense of tissue penetration, so this will be where the difference in OCT versus Ibis come, come to play a little bit. You know, the OCT, I think it's really interesting. You get both better axial and lateral resolution compared with ibis. So for example, why does axial resolution matter? You know, well, maybe you need to see. I, I included a, a stock image here, but, you know, maybe you're seeing someone who has a, a stent placed before, you wonder, is there coverage of that stent? Is there, um, neo atherosclerosis, um, um, you know, whatever it may be, that axial resolution is going to allow you to see really, really, uh, fine tune, um, at a fine tuned level, uh, whereas Ibis may not give you that same resolution. And then also lateral resolution is better with OCT versus IBS, so something that comes into play, maybe if you're looking and you're assessing, uh, are two stents that I put in overlapping. I mean, uh, and yours always are gonna be, you're never gonna miss, but, uh, someone else might, and that lateral resolution would help you see the difference between, you know, between maybe a gap in your stents, or you can say, hey, these are overlapping perfectly. So that's, uh, that's the difference in the two. So I think, uh, both are good. This isn't gonna be some sort of, um. Uh, negative, um, discussion of ibis by any means. I think both are, are amazing, but, you know, I think OCT has some really, um, really neat applications. This is the, um, and, and by the way, this is, I'm not, um. You know, uh, promoting any one company or the other. I'm using, um, several, um, Abbott related, uh, products in my slides here just for, um, just to make examples here. So just to give you an idea of what the OCT catheter looks like, this is, um, their, um, their Optus, their dragonfly catheter. Um, this is just kind of what it looks like in comparison to Ibis. So, you know, um, and I'll show you what it looks like in the coronary artery here, excuse me. Well, OK. Well, let me show you. Um, well, uh, anyway, so, um, I, I had outlined the coronary artery here, but essentially, um, the proximal marker there, you're going to have that at the beginning of the vessel. Uh, you're going to have the distal marker at the end of the vessel, very easy. That's kind of what you see, uh, this here. And then, um, just, uh, you know, to note that, uh, the distance between the, the two, about 82 millimeters or so, just, uh, these are just for reference, um, here. And then the lens of the catheter is, is just distal, about 2 millimeters or so from the distal lens marker, which, if I knew how to use PowerPoint appropriately, you would be able to see it approximately right here just to get an idea of where the lens is compared to the lens marker. The proximal marker really gives you, uh, it frames a 75 millimeter pullback. And then now this is outdated, um, but in general, OCT has a pullback speed of about 36 millimeters per second. But as we'll talk about later, some new technology has much faster speeds. And, um, just an idea of the platform. Again, this is, uh, Abbott platform, but just an idea of what it looks like, um, and we'll see some more of this later. But essentially, um, this is what it looks like inside of the coronary artery, and then this is the information that it gives you in terms of length and then vessel diameter, um, total, uh, length of the, of the stenosis or lesion, MLA, things like this. Um, Uh, just for reference as we go forward, you're gonna see E and L here. So, L is your lumen and E is your EEL. So, just to get an idea, um, and OCT is really, um, you know, really important to know about EEL. We'll talk about that in a little bit in terms of lesion expansion, stent placement, things like this. You know, we'll go into a little um of the uh of the trials that, you know, I won't go super heavy in, in, in depth of those, um, one of these alone could be 40 minutes, but there's uh several trials that have shown benefits of OCT, excuse me, Iumian one. Um, you know, aluminum 3, we're, we're gonna talk about aluminum 4. There's the doctor's trial, um, but, um, you know, essentially, there's a, there's a nice foundation that OCT has laid that it can improve procedural outcomes. Um, in some cases, it's been shown to improve survival, reduce hospitalization. Um, in multiple cases, it's been shown to reduce mace, um, and, uh, usually those are, uh, in some of these studies are going to be composites, but we'll see some, um, you know, we'll see some trials where that's not the case. But there's been a nice framework and foundation led that OCT is beneficial. So just to go quickly through some of the major studies, one, really pivotal one is the Renovate Complex PCI study. It randomized uh in a 2 to 1 fashion, about 1600 patients to intravascular image guided PCI versus angio-guided PCI and among, and, and so this included. Both Ibis and OCT and about 70, about 3/4 or so were IBIS and about 25% were OCT in the intravascular imaging group. And this, uh, the pretty foundational paper, an important paper showed that intravascular imaging guided PCI led to a lower risk of composite death from cardiac causes, target vessel MI, uh, or clinically driven target vascular revascularization versus angio-guided PCR. Uh, or that, excuse me, um, yes, um, and here we, uh, I have a target vessel, uh, vessel failure here just an outline on the left side, and you can see, um. Um, improvement with image guided PCI, uh, percentage wise, and that's statistically significant, so let's target vessel failure. The other big study, uh, really, um, important that you guys probably know about is Ilumian 4, the optimal PCI study. This was, um, you know, the study I just mentioned, complex PCI was a combination of IIS and OCT. This is OCT direct versus angio-guided PCI. This was really interesting because it looked at high risk or complex lesions, so high-risk patients or complex slash high-risk lesions, I should say. The high risk patients were essentially patients with diabetes. Complex lesions could mean a number of things, but, um. You know, we don't need to necessarily get into that, but you can kind of imagine what that might include long lesions, super calcified lesions, CTOs, things like this. And it was a very robust study of about 2500 patients in 18 countries. And this study really wanted to look at what was the, the post PCI mean stent area, the target vessel failure during a two-year follow-up. Look, it also looked, um, secondarily at stent thrombosis. Um, you know, and actually, I should really say, uh, if you think about this more in terms of clinical outcomes, imaging outcomes, and then, and then, um, you know, risk or, um, or safety outcomes would be another way to think about these three outcomes. The results of Lumian 4 showed that the post-PCI mean stent area, so mean stent area matters a lot for people that may not know as, uh, you know, maybe as in-depth on this. Mean stent area is your post-PCI area that you're achieving. That is sort of your new lumen. And that has been shown in multiple trials to, in multiple studies time and time again to be more beneficial for target vessel uh revascularization, target vessel failure. So you want a larger new lumen, essentially. The more expansion you get with that stent, the better off you are. So that's why we care. And post-PCI MSA was larger, statistically larger in OCT versus angiography. Um, there wasn't a difference in target vessel failure between the two. There was no statistical significance, and, um, and, but really the, you know, you look here, I put, uh, in, in red. Maybe the absolute numbers aren't as impressive, but a 64% decrease in stent thrombosis between OCT versus angiography. So the MSA is important for the reasons I mentioned, and then in terms of outcomes, things like. Stent thrombosis that you could possibly get from an underexpanded stent, it shows statistically significant improvement. So 64% decrease in stent thrombosis. That's very powerful also because stent thrombosis, especially acute stent thrombosis, is a very morbid thing. Here, I just uh looked at, uh, I really like this study, um, aluminum 4, it's a aluminum-four substudy, just looking at calcified lesions, and essentially they took a subset of those patients in aluminum-four and took, um, you know, took out, um. A subsection of them with easier lesions, just looking at more complex calcified lesions, specifically, so long multiple lesions, if a stent was planned, at least 28 millimeters or more bifurcation strategy, if that was planned up front, a severely calcified lesion, ISR CTO, and again they were looking at final MSA, a two-year composite of mace, and This is also, uh, sort of a strange, um, two-year uh effectiveness and a composite outcome that I'll talk about too. Um, just, um, uh, here on the left side, you can see that, um, OCT guided PCI once again, uh, showed a statistically significant improvement in post-PCI mean stent area, so, uh, minimum stent area, excuse me, um. So, um, compared to angiography, guided alone, and then looking out at to your clinical outcomes, in terms of serious MC, um, this is this, um, thing we talked that we mentioned here, that's a composite of cardiac death, uh, target vessel MI or stent thrombosis. It showed a statistically significant, um, lower rate. There was again, no difference in target vessel failure between the two, but so I think, you know, here are two really good studies, and one is a sub-analysis, so you might imagine you might get the same outcome, but it showed um really good outcomes in complex lesions. Calypso trial is another one just to talk about. I mean, it was also looking at OCT versus angio guidance alone in PCI for calcified lesions and. Um, again, this showed that post-PCI minimum stent area was statistically larger in the OCT group compared to the angiography guided PCI group. Um, here, you know, this was, um, the reason I put this in the calypso trial, they really mandated that the, um, that the, the participants, the physicians that were doing this, um, follow this regimen of how they were gonna treat each lesion. So I just added that in, in case anyone was interested academically, but essentially they kind of mandated that they follow this calcium modification protocol, but essentially, with everyone following this, uh, this, you know, kind of robust protocol, that we still saw those, those good outcomes like I mentioned. And, um, you know, in addition to MSA, um, uh, you know, minimum stent area being uh statistically better, um, there was also a statistically significant improvement in major malapposition among the AOCT compared to angio. So, you know, malapposition, there's a little bit of argument is, you know, how important is that, and there's been some studies looking at, you know, maybe proximal malapposition is most important. Obviously malapposition associated with dissection is important, but still an interesting finding and shows some improvement OCT versus angio. You know, really, um, uh, aside from the Greg Stone trial that I mentioned earlier, this is, uh, one of the ones that's gotten some of the most press, the October trial. Uh, this came out, um, in New England Journal of Medicine. And, um, You know, won't, uh, you know, get, uh, too much in the weeds here, but essentially was looking at angiography or OCT guidance for complex bifurcation lesions. And you can see here, um, they had this rigorous protocol that they went through, but essentially, um, you know, they did their pre-OCT run. And um then they used OCT guidance, they used OCT guidance to perform their bifurcation strategy at each step. So, um, they've made sure each um osteo, were covered on each step. They've made sure, um, you know, so very intricate. They were making sure adequate wire placement every time they're recrossed in these complex bifurcation stenting strategies. So, um, with that, uh, OCT guidance showed improved outcomes. At 2 years compared to angiography guidance alone. So this is another sort of high risk scenario where OCT was shown to be beneficial compared to no, no imaging. Um, not super surprising to most of us, maybe, but again, it kind of laid the foundation for OCT and and you know, made its use more supported and robust. Almost done reviewing trials. So just to go over another one, real quick is Octavivus. So that compared OCT guided and IVIS strategies, uh, for patients, um, going under, you know, doing several different types of, um, of coronary lesions. And, um, you know, really the reason I added this in is in terms of, you know, we, I think we, we know that, uh, intravascular imaging is better than coronary alone. Um, this, um, really was looking kind of a head to head more at IIS versus OCT. And it showed non-inferiority. So I think my takeaway from this and, and some, you know, we'll, we'll mention a few things later is that OCT and IBS are both good. We should be using some sort of intravascular imaging. I think, um, you know, I wouldn't say one is necessarily better than the other, uh, just in general, um, and, and just throw that out there, but I think each has its own silo that it's much better at. And we have to use those tools in our toolkit. Uh, something, um, that I wanted to throw in, uh, that we'll, it's gonna come back a little bit later, but I think it's interesting is that, um, some of, uh, the modalities that we have already, um, you know, we have Cathworks here, we, uh, have all used FFR IFR, RFR, and, um, and there's been a combination of tools into 11 platform, and Um, that is something where I know of, you know, one company that has already done this and a couple of others. I've, I've heard rumors that may be coming fairly soon. But, um, essentially, the fusion study looked at um OCT-based functional stenosis assessment, and they use this virtual flow reserve, which I don't know all that much about, but um. It's basically an OCT based uh physiologic index that, that seems to correlate with our FFR, um, you know, in general, they studied that correlation in the study. They were also, um, you know, and, and they have a few interesting findings that I'll bring up. They also were just comparing. OCT images um compared to angiography and just performance overall, I think they had some really interesting findings too, so we'll talk about that. In terms of the comparison of their, you know, their functional assessment versus FFR, it had pretty good sensitivity and specificity. You know, really, the authors talk about if they, you know, there's sort of a gray zone for them, but if they lower their cutoff below 80 or 0.8, I should say. Um, that really improves the sensitivity and specificity pretty robustly. So, um, it felt like this was, um, pretty well correlated with FFR in general, and you're going to see that that's, um, that's gonna be combined in platforms. So you're gonna be in the future be able to get your OCT, your FFR, your or your, uh, physiologic guidance all in one place. These are some of the findings I thought were, were kind of neat the way that they presented them, and this is just talking about stent over and underestimation by OCT and angio. And what they looked at was the, the planned stent diameter and then what actually happened. And you can see that really most of the people that, that used OCT, there wasn't a lot of change. So. Um, you know, I think this is important for a lot of reasons and kind of um harkens back to, um, to some studies too that I'm not gonna talk about that have shown OCT is really efficient, so. Um, you know, ibis is efficient too, I think if you have your, your table set up and you know how to run it, but OCT can be really efficient for your pre-angio, for example, you, you run, you get a size, you get your morphology assessment, you go through your MLD Max, which I'll talk about, and you don't have to do all that again. If you say, well, maybe, um, you know, let's go back and measure that, uh, fine, but you really are gonna be done with it here. Um, and then you are not really going to change too much on the back end because you're getting such an accurate assessment. Maybe that's not a mind blowing finding, but I thought it was interesting the way that they laid this out. So you see, um, several, uh, uh, a good percentage just by visual guidance alone, undersized and oversized their stents. And then also in terms of length estimation too, even more striking the uh the number of people or number of um uh uh cases that were under or over. Estimated in terms of length and really, I mean, underestimating the length, you know, you're landing in some sort of a lesion there that can be pretty damaging. Ultimate trial has shown that landing in a 50% stenosis or lesion is bad news, so that's obviously pretty striking. Just more evidence to use imaging. And the next part of this, I'll go, it's a, it's kind of fading out of, um, of the trials, which some people that are sleepy may be happy about, but, uh, it'll go more into the, the clinical utility of OCT and how we do it. But I wanted to talk about this trial in terms of utility and overall impact. So, there was a, this thing called the Light Lab Initiative, and they used this algorithm called MLD Max for OCT workflow, and I'll talk to you about that in a little bit. And essentially this, this prescribed algorithm, very easy to remember, very easy to use, they compared that. Um, or they looked at how that impacted their procedural decision making. So it not only shows here how it changed their decision making. In terms of escalation of therapy, de-escalation, no change, but then you can see on the top there it shows the cumulative impact that it made on the decision making throughout the case. So I thought that was really elegantly laid out and basically it changed using the MLD Max OCT algorithm. Uh, it changed their decision making in 86% of lesions, so pretty, uh, high number right there. Um, you know, and in terms of pre-PCI, um, OCT, it changed their decision making in 80% and 31% in post-PCI cases. When they took out the impact of lesion type or the morphology assessment, the workflow still changed procedural decision making in about 77% of lesions. So you see vessel preparation, for example, which I think is extremely important to note is that 21% of the time there was an escalation in vessel preparation. Of course, you know, de-escalation can also be important, not damaging the vessel, but also there was a 30% escalation in total stent length, getting back to sort of what I mentioned earlier, and a 22% change increasing in stent diameter. So, you know, assuming they're not oversizing or over, you know, overestimating, you're getting better coverage here and better outcomes. So I think that was really neat to point out. Also, this is also from the same study. This is really just looking at the calcific disease. So. The change in vessel preparation was largely, you know, in terms of a percentage driven by calcification that they found. So 85% of calcified lesions, excuse me, underwent a more aggressive form of preparation than they had originally planned on doing just based on visual estimation of angiography. 55% of these lesions were treated with some sort of atherectomy, laser specialty balloon. And then another 45% of them using this uh algorithm upgraded to either an NC balloon from a semi-compliant balloon, or, you know, they had planned to not really do any preparation, but they at least ballooned afterwards, um, and OCT changed their mind. And what did they use? They used uh MLD Max. And so I'll talk to this, um, you know, maybe some people haven't used this before, maybe some people haven't used it in, in a while. So, um, it's a really, uh, I think, easy to remember algorithm that makes a lot of sense. So I'll go through and give a, a couple of examples. So, MLD is your pre-PCI run, and Max is your post-PCI run. MLD is you're looking at your morphology, your length diameter, and then you're looking at medial dissection for your max apposition and expansion, so you're prepping your vessel and then afterwards you're seeing is everything OK? Do I need to do any more work? Pre PCI, um, you know, not to go into that too much more, but morphology, um, you know, this is using, again, um, just using, um, the, um, the, uh, the, the Abbott technology, I'm kinda gonna go off of that, but it's not, um. Not focused on any other platforms, but I think these are good examples. So morphology with these platforms, and Abbott has one, there's other ones that do similar things. The morphology, you're going to be looking at obviously visual estimation, but you'll see that a lot of these, if you haven't used them in a while, are automatically detected. Automatic calcium detection. Uh, automatic, um, and now they have automatic calcium detection in the sense of the rules of five, you know, with OCT. So, for example, you might have to think about before, what is the arc of calcium, what's the thickness and the length, that's now automated for you by artificial intelligence. The length is also automated for you, so it will automatically detect by AI the EEL for you. And it will in a lot of interesting ways, but it will detect the EEL throughout, but it will also find optimal landing zones proximal and distal to your lesion, and you can sort of say, hey, this is where I think the lesion probably should be. It's going to search with artificial intelligence, distal and proximal, and find that EEL for you. And then give you uh sizing recommendations and um in diameter I mentioned with the EL. So just, um, uh, again, a little background. So what we're thinking about here, this is our, our, this is not an eyeball, I confirmed, this is an OCT catheter in a coronary vessel. Um, that's our lumen. And what we're looking at here is our intima, media, anadventitia. And really, you're thinking about your external um elastic lamina, and that has been shown to be a safe way to uh to balloon and stent folks, um, to get, get a really good result um but not overtreat them. So with the morphology on OCT, I thought, I think this is a really sort of easy way to break it down. You know, uh, you might, uh, hear a few, you know, this is the sands on the ocean and things like that. I, I don't know, you know, that can get kind of confusing in terms of is this a fibrous plaque, you know, um, what is the morphology. Uh, this is a, a fairly easy way. So, can you see the intimate media and adventitia, can you see that inner lining? Yes, then it's either a normal vessel or it's probably fibrous, fibrous plaque here. And then if you can't see it, so you say, well, is it a thing, is it a problem in the wall or is it a problem in the lumen? So if there's something going on in the lumen, if there's low attenuation, it's most likely a white thrombus. If there's higher attenuation, you can't see back there, but there is a, it's in the lumen. You see the red thrombus here, you can't see behind it, but there's something in the lumen that's going to be more likely a red thrombus. And then if it's inside of the wall, again, if it's high attenuation, you can't see what's beyond it, that's going to be most likely a lipitic plaque. And if you can see, you know, you can see on the far right there, you can outline that, you can draw a line around that lesion that's going to be calcified plaque. That's a fairly easy way I think to to find the morphology. This is just another way of presenting the exact same thing I just said. He's the, the same examples, maybe some better examples of intrauminal problems here. And then, um, you know, for me, sometimes it can be difficult, uh, to really tell the difference between lipitic and fibrous plaque, but, um, I think if you're, if you're able to see your, your inner lining, your EEL, um, here, then, again, most likely, it's going to be a fibrous plaque instead of lipitic plaque, to help you treat them better. This is, uh, the other benefit of Ibis or excuse me, OCT is, um, you know, it's going to not only tell you, um, you know, what type of things you can use, but, um, how much to use of those things. Um, in terms of this, I thought this was a nice example. You know, lipitic plaque, you can tell that you might consider direct stenting. Fibrotic, you're gonna, you know, maybe use a compliant or possibly a cutting balloon. Uh, you can distinguish between moderate, mild, and severe calcium, and then kind of choose your, your poison there, which you're gonna treat it with. In terms of morphology, just the other thing that I mentioned with the rules of five for those not aware, um, it's just a, it's a scoring system that's been validated to correlate with need for atherectomy and. So, um, essentially, you can see over there on the far right side, the original score is if the arc arc of calcium is greater than 180 degrees, so more than 50% of the vessel, so 5, if the calcium thickness is more than 0.5 millimeters, 5, and if the calcium length is more than 5 millimeters. Then you're going to get points for each of those. Anything in terms of 2 or less, it's been shown that you may not have to use advanced strategies, but if you have a total score of at least 3 points based on the rule of 5s, it suggests that you need some atherectomy. You might need intravascular lithotripsy. And again, so that's been shown to uh to correlate with better outcomes if you treat with those um those advanced those advanced modalities and better outcomes in terms of calcium fracture and patient outcomes in terms of how well the stent does long term, I should say. Just another way of showing it here. So 50 here, 50% arc, you've got a depth, you can see of 0.5 millimeters, and then you can see it here on the length, it's more than 5 millimeters. And again, the nice thing is, um, and I may have a slide to show, but the rule of fives is automated now with artificial intelligence. So they'll just have your rule of fives there, they'll give you your score. You don't have to worry about this for people who don't like math. Uh, just another comparison, uh, you know, of just between the two in terms of morphology, just, uh, what you see with ibis and OCT. Again, ibis is good, it's better for lipitic, uh, plaques and things and fibrous plaques, uh, definitely than OCT, but you're not gonna get this, uh, depth, uh, or you're not gonna be able to see your calcium as well with ibis, um, as you are with OCT. So you can really tell exactly what's going on in terms of your, your calcium. You can see, hey, um, you know, here. Who knows? I mean, you say, oh, maybe I'll be able to crack this, but instead, maybe it's a, a very deep calcium that you need, uh, orgoarterectomy for or a, a cutting balloon. Just to note, um, in terms of morphology and, and when you're thinking about sizing, uh, for OCT, so you're gonna use your EEL based, uh, system. And I, here I talk again about your, your EEL automatic detection by AI, which is pretty interesting. So, um, uh, there it is there. So, your EEL is detected. They've got it highlighted for you. And, um, They're going to give you EELs, um, again, proximal and distal to the vessels, so it's going to help you with your distal and proximal sizing. This, uh, just briefly is, um, is the length, uh, and, you know, it uses co-registration and. It gives a really nice luminogram of the artery. Um, again, so they're gonna find the EEL for you, proximal and distal to the reference frames that you select for the lesion, and then it's gonna automatically calculate that distance. And the neat thing is too that it will also sort of round down or round to the closest stents length size too. So some of these don't correlate with normal stent lengths, but they'll also give you, um, it'll round down too, um, and they'll give you both of those numbers. With, um, you know, diameter, again, it's EEL guided strategy, um, with the EEL measurements, you're gonna round down, um, in terms of your device size, your stent size. If you can't see the EEL in some scenarios, so what you're gonna do is use the lumen diameter, uh, you're gonna use the mean lumen diameter and you can round up either a quarter to 1/2 stent size. And then, um, you know, you know, it makes sense, you're going to use the proximal and distal measurements that are going to be provided for you or that you can see yourself with the EEL and that's going to help you to size those sizes respectively. And I just mentioned that. Uh, co-registration is very nice. I think it's, um, it's very helpful and sort of they have this live angiography where you can zoom in, uh, and take a look. Um, I think it's really helpful. So, um, there's, uh, just mention here that there's been, uh, a couple of studies, uh, including one randomized study that showed that OCT guided, uh, co-registration. Uh, aided in more stent, uh, precise stent deployment, excuse me, and it eliminated large geographic misses, which we hinted at earlier with some of those studies and trended not statistically significant towards reducing major stent edge dissections versus angio alone. And again, you know, here for people who haven't seen it lately, um, you can see the co-registration, you know, um, you have this on other devices as well, just highlighting your distal proximal reference zones, and you can sort of scroll up and down. For post-PCI guidance, so we talked about MLD. This is Max, your, the M is medial dissection, A is for position, and X is expansion. So for your medial dissection, uh, the, this is also, uh, really interesting. So, um, artificial intelligence can help you here. So, you, um, you're gonna use your reference segments that you have post stent deployment on your OCT pullback. You're gonna, you're gonna be able to kind of just go and pop right to those proximal and distal edges and check for medial dissection, intramural hematoma, something like this. Um, there's a guidelines for what that really, you know, means and what's, uh, significant. Lumum 4 categorized major dissections as a more than 60 degree arc, um, from the center of the vessel and more than 3 millimeters in length from the edge of the stent. Um, you know, we can talk a little bit more about that, but, you know, some, some criticism of OCT is that you're seeing more, you don't need to treat it always. That's true, but I think um there's some pretty good guidance out there, um, on what to do and what not to treat, and it has been pretty well validated. And just, you know, to add here that. You know, distal edge dissection associated with bad outcomes, obviously long term, so it has to be checked and you know you can't do it at all or you can't do it very well with angiography alone, but then even Ibis have a difficult time sometimes when I'm pretty sure it's a dissection, I still have a difficult time confirming. This is just some more examples of what on OCT, uh, those dissections looks like. You can see just an internal dissection, uh, more of a medial dissection, and then a big uh intramural hematoma there. So getting more significant from left to right. Apposition. I talked about this, uh, you know, really already, but this is just what it looks like on OCT. So, you can see here, your stents, um, is well opposed. And the nice thing is, is that your OCT systems are gonna highlight where your acquisition is occurring. So, you can see there's that position right there. It's highlighted for you. Some, uh, systems, it's red or orange or blue, but whatever it may be on whatever platform you use. But it's gonna tell you from your luminogram or, uh, your prostate. where you're opposed. And so you can, you can look, you can say, is this because of there is automatic detection of side branches, but you can sort of go in, see what the real problem is, and then this is where some of the 3D rendering that is available in some technologies is pretty neat, not only with bifurcation, stenting and things like that, but you can see a little bit more about your acquisition. Inside branches, so you're not uh overtrading there. But um again, a lot of that's going to be automated by, by artificial intelligence. And I just mentioned here that, um, after stent, uh, after stent placement with Ibis, there's stent malposition that was noted in about 15 cases, or 15% of cases observed by Ibis, but OCT picks up on about 50% of those, so more, um, sensitive there. It's just um. A little data on acquisition and, and really OCT and IVs have been shown to improve mace and improve long-term outcomes in some of these studies. Some of them are not always statistically significant, as you can see, but there are definitely trends towards improving long-term outcomes with improved acquisition with intravascular imaging and specifically OCT. Expansion, we can really get into the weeds of what expansion really means, what is good expansion. So European consensus is that a minimum stent area we talked about earlier has to be 80% or more of the mean reference limit area, and then that's about 4.5 millimeters squared on OCT. OCT is gonna give you a couple modes um to, to look at in terms of stent, um, expansion assessment. Uh, that's a little bit in the weeds, but they're gonna give you multiple modes that you can select. Again, you can, um, use, um, you know, kind of a, a self-reference mode where you're um looking yourself, or you can use the OCT detected mode where they're looking at those side branches for you, so you're not overtreating or inappropriately treating and. If, um, if stent under expansion is noted on the, the post PCI OCT outside the stent and inside the stents, um, you know, measurements are sort of highlighted for you, and they're gonna remeasure the vessel, compare it to what it was before, and then, um, and again, that's using EEL guidance. If you can't see, um, uh, things, uh, the, if you can't see the EEL very well, I should say, the software is gonna go based, is gonna go off Lumen guidance at that point. Something else, um, here, um, what we said, I just want to highlight, um, here, uh, you know, again, some of, um, some of the different softwares are different colors and different highlights, but essentially, they'll give you your percentage expansion, um, a percentage of what it should be based on either EEL or Lumen. Um, we mentioned, you know, some of this, but acceptable, um, and a goal, acceptable goal would be a minimum stint area of 80%. And then an optimal would be more than 90% or so of that mean reference luminaria. Again, um, you know, even more so than than malapposition, expansion is very important in terms of driving mace. So you want more expansion. We want things that will help us with expansion, and this definitely does, um, you know, highlights it for us, tells us exactly where it is. You don't have to guess. And then, you know, I didn't add this, but it has a lot of really interesting features too, where it will tell you the amount. The distance from the EEL and the lumen that the expansion is, so you can say, well, that's sort of within normal parameters. I'm not going to mess with that even though it is technically abnormal or this is at a side branch or something, so it also gives you more information instead of just kind of blindly saying this is posed or excuse me, this is underexpanded and just treat, treat, treat. So it gives you some options there to where you can be a little more precise. Here, um, You know, just, um Another, uh, I thought a nice visual example of expansion. So there at the top, you're looking at, at, uh, A, it's giving you your, your expansion and your under expansion and the mid vessel, it's given distal vessel, and it gives you your percentages there, 58, 52%. And um Uh, you know, kind of makes sense, but they're, they're giving you these references of your, your target expansion based on EEL and your actual expansion, and that's how they drive that for you. But again, I think it's really fast and nice, so you're not hunting around and looking with something with lower spatial resolution. You have taken a beautiful picture that you can do 3D renderings of or the luminogram, and it highlights it for you. It gives you your MLA and diameter, whatever you want. Just a quick note on artifacts, that's a, you know, a criticism of OCT and we could, you know, go into that quite a lot, but that is a limitation of OCT. So whether it's from light propagation from the catheter, the luminar vessel wall, uh, or the location in the wall, you know, if it's. Uh, you know, stuck against the wall, you, you may get some artifacts. So that's something we have to, to watch out for. You know, the big one you think about is, you know, inadequate flushes. You're, you're not getting a really nice picture. Uh, there's some, you know, cut, uh, rotational distortions you can see on the luminogram or the axial cut there. I hope the catheter prolapse doesn't happen, but that's possible, um. And, uh, you know, just some things to note, you know, the, the lack of blood clearance too has been uh one that when I was uh first learning OCT was, that was really one of the bigger criticisms of it. We're gonna see that that's kind of going away now with some of the new platforms. I mentioned some of this just to, you know, uh, again, ibis and OCT, um, should be a, there should have been a pop up here between those two, but, you know, comparing the two, I, I think is very helpful. They're both tools in the tool shed. Ibis is gonna give you, like I said, you're going to see better lipitic plaque, better fibrotic plaque. OCT you're gonna see your calcium better, but. You know, really, you know, thinking about other things, CTOs, probably you're going to use ibis, you're not going to want to use OCT and OCT because you, you don't have that coverage that you need, OCT is pretty, pretty poor at getting aorto osteo coronary segments and specifically left main. You know, you could possibly use it for distal or maybe mid left main cases, but the osteo left main is going to be out. Uh, just a couple, um, images here, um, that just thought were interesting, um, you know, uh, just some, some neat, uh, examples. One is OCT and AC ACS. So this is. Uh, this is just, um, a thrombus here in D and E. You see a plaque rupture. I'm just gonna give some. Interesting pictures there. Um, there's some, uh, some A, you see some, uh, denudation there in that that artery wall, and then that is a plaque rupture there in B. And that correlates with, with the uh co-registration you see in the top right. Just a look at some calcium nodules, which may be the most impactful and helpful. You can tell, no, this isn't some sort of a rim of calcium that's not very thick. That is a gigantic gnarly calcium nodule that's eroding into the vessel wall, so you're going to need to bring out the big guns for that. Uh, this is, uh, what I was talking about earlier. So, the, you know, these new platforms, they'll detect calcium automatically for you. So they'll highlight it for you, and then they're gonna give you, um, you know, you know, thick, of course, you're getting your other measures that I mentioned, and I don't think I showed it here, but you're also gonna get your thickness of your calcium, your length of your calcium, your arc of your calcium, which you can see in the top right, and then it'll also calculate your rule of fives for you. Um, just, um, some things we've already really talked about is that automatic calcium detection and the fact that You can, um, you know, that's very important. Also, you can, uh, set this, where you can detect the threshold for what it tells you. So if you, you know, this is all customizable, but if you don't want to know about 27, you know, you know, less than 30% arc of calcium, you can set it to, to ignore it. So it's not giving you all these false alarms, just some other really neat pictures of calcium nodules, and you can see how much more information you're getting here versus ibis, for example. And this, I think is, is great too, where um it gives an example both of you don't really know what you're getting in for because that's a much deeper than it, especially there than it seems on ibis on the bottom, but this is after you have treated the, the vessels with some sort of calcium modification, you can see your, your calcium fractures there. So someone's done a good job. Um, just briefly, I think OCT is kind of where I wish I had it. I, I have an interest in Minoa, and, uh, there's some cases, you know, a young person comes in, they have, uh, you know, a significant troponin elevation, really can't see anything to go after even with Ibis. You don't, you know, really know. Maybe there's something hazy, um, but OCT can be really helpful to identify these more subtle plaque ruptures, plaque erosions. And, um, you know, they're reporting at a big sort of a lipitic plaque with the necrotic core. Um, would use this with caution, but this is just an example of OCT and SCAD. I seem to be on a SCAD run, so I added this in there. Keep the scaries away. And um you know, just to mention briefly because this will come up is that there's a lot of there's a lot of research interest in looking at high risk plaques on OCT. This is still in the beginning stages. There's some data that says these high risk plaques that aren't you know significant in terms of stenosis may be targets in the future to go after. So that's just on the frontier. But you know, whether it be vas or. Um, you know, you know, necrotic cores, this may be where we're heading in the sense of detecting these lipid rich plaques, these vulnerable plaques, and, you know, is it beneficial to stent them, you know, upfront? Do they have better long-term outcomes. So far, the study has shown that you need, you know, several years, 23 years to show some outcomes from this, some benefit, but that's where we're heading potentially. Um, just, uh, another couple interesting images, this, uh, just a, uh, stents assessments of with OCT, and I think again, this is a cool 3D rendering. I don't know how helpful that is, but I think it's very nice because again, um, that's a big thing that again you, you would like to have OCT for is someone with instant, an instant problem. Is this a very light stent thrombosis? Is this a. Fracture, what is it? And the treatment does differ quite a bit based on those things, uh, you know, from a stent fracture versus neo atherosclerosis, which can, you can get a plaque rupture inside of that potentially, or is this some other problem with the stent? I think this is also where it kind of shines bright. Um, I'll go into that. And just um a couple of future directions to leave you on, and um I think this is really what's got me the most excited. Um, you know, we talked about blood clearance is needed for OCT image, and that's been a burden for people with, with kidney disease. The use of extra contrast is always, um, you know, a thought you have to keep in your mind. Um, somewhere around 30% or so of OCT patients are ineligible for OCT. In the past because of those kidney concerns, but a lot of this is going away. And one thing, um, you know, a couple of things in terms of new directions. Number one is what I mentioned earlier in terms of, you know, getting out in front of these vulnerable plaques, where are we headed there? That, again, I didn't focus on that. It's a little more controversial, so I didn't nail down on that, but we have to keep our, our head on a swivel there. The next things in terms of, of technology though is micro OCT and deep OCT nears. So, there's a company, uh, you know, Spectra Wave is the name of the company that was recently acquired by Phillips, and I don't know if you guys have seen their images, but, um, you know, essentially what this does, and this is the game changer I think that I was kind of alluding to earlier, is that you get a combination of OCT. You get, um, um, you know, spectrometry, so you basically get that in, you know, the, the benefit of ibis essentially. So, um, it can not only give you those beautiful images like OCT but it can see deeper through lipidic plaque and fibrous plaque like ibis can. So you're gonna get that deep, that's why they call it the deep OCT. You can see deeper into the tissue. So essentially, it looks like you're combining ibis and OCT. You're getting the best of both worlds. Also with their platform too, it has um FFR in it as well, so you can get a um. You can get your OCD. You can get essentially ibis in the same image. You can see deep lipitic plaques. You can get an FFR if you want, and you can get microvascular resistance. That's all coming in one platform and that's available. But best of all, I think, uh, to that is that they have now made it where this is not contrast. This is. Saline flush and that's where I was hinting at earlier. I've I've heard rumors that this is coming for some other platforms where no because of the pullback speed they're not going to need any flushes whatsoever. So this still needs a saline flush, not a contrast flush, because of the super rapid pullback speed. And I think some other platforms are getting the same thing. I've heard rumor too of, of no flush at all, not, you know, um, uh, I don't, I don't know, uh, about that, but with this one with the saline flush, obviously it's very safe for patients with kidney problems. So really, uh, remarkable. It's sort of taking out a lot of those reasons you wouldn't use it and, um, and giving you a, a ton of extra information. So I think it's. Uh, heading in some right directions here. I didn't, you know, maybe these aren't the best examples, um, that I added here, but that's OCT on the right, and this is more, it's not the best example of deep OCT, um, but, um, you can see, um, you know, some. Uh, you can, with deep OCT you can see, uh, you know, lipitic plaque. That's I think that was what I was trying to show there. And I think that's all for me. Um, you know, I appreciate you guys taking, uh, taking the time out to listen today and, and participating, and I'll take any questions you guys have.
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