Percutaneous Coronary Interventions (PCI) for Chronic Total Occlusion (CTO) – When, Why, How

Podcast Transcript

Announcer:
Welcome to Cleveland Clinic Cardiac Consult brought to you by the Sydell and Arnold Miller Family Heart, Vascular, and Thoracic Institute at Cleveland Clinic.
Dr. Jay Khatri:
Good morning, everybody. My name is Jay Khatri. I'm director of complex coronary intervention at the main campus at the Cleveland Clinic. Today, we're going to talk about CTO PCI. I'm going to go through some of the prevalence and the indication for therapy and when to refer a patient. We'll go through some of the definitions and the prevalence of CTO in coronaries and the clinical significance of having a CTO. Why does it really matter? And then I'll go through the benefits and when and why to refer somebody for treatment. The best way to think about patients with CTO is they're a subset of a much larger population of patients that we take care of every day, patients who have ischemic burden from incomplete revascularization, and we have a certain way of managing these patients based on their coronary anatomy. And for whatever reason, because of technical issues and limitations to management strategy, CTO patients are kind of set aside, even though they're really just a small subset of this much larger patient population that we already have some treatment algorithms for.
The best way to understand this is probably a clinical vignette. This will kind of put this into a crystal clear focus what I'm talking about. This is an actual patient of mine. He's a 55 year old male. He was an avid runner who presented with a three month decline in exercise tolerance. He has a history of hyperlipidemia and was on Astatine already. There is a strong family history of premature CAD. He had a pretty unremarkable exam. His ECG showed a left bundle and he went for a spec scan. And you can see on the spec scan that there is pretty significant ischemia involving the inferolateral wall with preserved LVEF. This is what you want to see in the cath lab. This is an angiogram of the right coronary artery with a very discrete focal lesion involving the distal right coronary artery proximal to the crux. This is something that anybody would treat without question and feel very good about that they had done a good job for this patient. So there's nothing controversial here, and there's nothing really to discuss. This would be pretty straightforward.
The more challenging situation would be is if the angiogram showed this. So more diffuse disease involving the ostium of the PDA, some diffuse disease involving one of the circumflex marginal branches. So we said that the patient had inferolateral ischemia. And when you had these borderline lesions, the ideal way to assess this in the cath lab is to do some sort of a hemodynamic assessment with an FFR protocol or a resting gradient protocol. And so from this, we know that the PDA probably doesn't need to be fixed, whereas the circumflex should be fixed. And so you can feel very good that you've used evidence-based medicine to manage this patient appropriately and manage their symptoms. And this is born out in the FAME trial. I'm not going to go through all of in detail, but we know that from FAME and trials like FAME, that hemodynamic assessment of borderline lesions is superior to angiographic assessment in terms of late events. And that PCI and hemodynamically significant lesions is superior to medical therapy when there is a hemodynamically significant lesion proven by pressure wire.
But this is the angiogram that my patient has. So this is a patient that I took care of a few years ago, who has a total occlusion of the proximal right coronary artery with robust collaterals from the left system. And this is where things kind of fall apart. I mean, what do we do with this patient? It kind of depends on which hospital you show up and in terms of what the recommendations are. I mean, he doesn't really have a lot of left coronary disease.
The ischemic burden that would warrant PCI has been identified in historical literature. Anything more than 10 percent ischemia on a spec scan is determined to be associated with adverse cardiac events and potentially benefit from revascularization. This is even seen in the COURAGE trial. So, I mean, we think about the COURAGE trial as encouraging the medical management of CAD, but in the nuclear sub study, the COURAGE trial, they did identify a subset of patients who did benefit from revascularization with PCI. And those are the patients that had at least 10 percent ischemia on a spec scan. So based on some of this historic data, we use a cutoff, it's a little arbitrary, but a cutoff of around 12.5 percent on a nuclear study of myocardial ischemia and where we think patients would have some clinical benefit from CTO PCI. This is also a born out in some level in larger trials, like the SYNTAX trial.
There's a CTO subset analysis of the SYNTAX trial, where they looked at the impact of incomplete revascularization on four year event rates. And they show an association between incomplete revascularization on four year mortality revascularization need and future mace. And the biggest predictor of incomplete revascularization in SYNTAX was CTO. And you can see that in the PCI arm, nearly half the patients with CTO ended up with incomplete revascularization where it's about a third in the cabbage arm. So even in the cabbage arm, CTO patients were not being re-vascularized. One thing that needs to be added is that the CTO PCI attempt rate in syntax is pretty low by modern standards, but it just shows how important this concept of incomplete revascularization is on long-term outcomes. Now, this is also seen prospectively. So this is data from the SCAAR Registry. So in Sweden, anybody who has a cardiac catheterization in Sweden is followed in this database and you can see the long-term outcomes of patients who present for catheterization for any indication.
So you look at the six year outcome data and how much higher the cumulative mortalities in patients who had a CTO at the time of their index coronary angiogram. And you can also see on the panel to the right, that there is a clinical benefit of successfully opening the chronic total occlusion. Although the temperatures were pretty low and the success rates were pretty low in the SCAAR Registry, but there is a beneficial impact. And it seemed to be strongest among younger patients who presented with an acute coronary syndrome. And that sort of supports this prospective data, which looks at patients who presented with STEMI and had a concomitant CTO in a non-infarcted artery. You look at the dramatic impact that having a CTO at the time of STEMI has, both acutely and in the long-term, on mortality. So it's not a benign entity to have the CTO. It's something that portends a sicker patient with a worse outcome. Now, whether or not treating this a CTO is going to improve that outcome is obviously debatable, but we're identifying a patient who's at a much higher risk of an event in the future.
What does opening the CTO offer the patient? This is sort of a busy slide, but basically what I want to tell you is that in several large registries, open CTO probably being the most relevant one currently, because of all the adjudication of events in this registry, that's 1,000 patients done again again in the US in several large volumes CTO PCI centers, and what they show is dramatic improvements in quality of life indicators, with successful CTO PCI. So there is some objective evidence that patient's quality of life improves after CTO PCI, but what about more clinical evidence besides quality of life?
So going back a few years, this is a study looking at the utility of MRI and predicting clinical benefit. And really what I want to show you here is that in patients with CTO who had less than 25 percent transmural scar, it basically people who had viability in their myocardium, there was a dramatic improvement in segmental wall thickening in these patients. And they saw this improvement in LV function very, very quickly within five months after CTO PCI. And this result was sustained up to three years. So some objective evidence that LV function can improve with CTO PCI. There's some more current prospective trials that I want to share with you looking at this concept. So this is a prospective study of only 50 patients looking at MRI proven ischemia and viability, and showing the results of successful CTO PCI. And what they were able to indicate is that there was an improvement in LVEF as well as myocardial profusion, as well as quality of life indicators in people who had MRI proven ischemia and viability who had a successful CTO intervention. So some objective evidence and some quality of life improvement evidence.
This is a trial looking at it slightly differently. Another smaller trial, 69 patients, which looked at PET proven ischemia and MRI proven viability, and they had successful CTO PCI, and they showed, again, improving myocardial blood flow between the pre and post PCI, and as well as improvement in LVEF. So looking at it slightly differently using PET for ischemia and MRI for viability. I'm bringing these up because we use all of these modalities in our patient assessment. So what do we know in overall from all of this data? From meta analysis of the observational data, we know that compared with a failed intervention, a successful CTO intervention in a symptomatic patient is associated with lower all-cause mortality, lower MACE rates, reduced need for subsequent cabbage, and a increased rate, unfortunately, for target vessel percutaneous revascularization. So there is some risk of re-stenosis that has to be dealt with.
Now, this is a very different patient population. I stress the point that these are symptomatic CTO patients, whereas the trial that most of the naysayers will always quote is the trial. Now, the ODE trial was a randomized clinical trial that showed no clinical benefit of opening a totally occluded artery, but this was a subacute infarct related artery within a month after an acute coronary event. So these are asymptomatic patients who basically have completed an infarct. So it's not what I'm talking about. We're talking about stable patients who come in electively who have symptoms and have their CTO taken care of. So what about the randomized clinical trial data? So this is the Explorer trial. This is a trial done in Europe, looking at patients who presented with STEMI and then had a subsequent CTO intervention on the non-infarct related artery. And what they showed basically, is no significant improvement in LV systolic function, which was sort of contrary to some of the data that I showed you so far, but there is something to be gained from this.
What they did find is that there was some benefit in patients who had an LED CTO PCI. So that was in a subset analysis. It's too small of a study to really draw too many conclusions from that, but they did dig into this a little bit deeper. So instead of looking at overall ejection fraction, they went back and looked at the dysfunctional segments and look for any improvement in contractility, in the specific dysfunctional segments that were perfused by the CTO. And in that situation, they did show an improvement after CTO PCI in the dysfunctional segment. So rather than looking at the overall injection fraction, because you can make the argument that the areas of the myocardium that are profused normally may be able to compensate for the dysfunctional segments, making an overall ejection fraction pretty normal. So making the detection of a change difficult. So they went back and just looked at the dysfunctional segments and they did show an improvement in LV function in those dysfunctional segments.
This is another prospective trial, randomized clinical trial done in Europe, looking at patients with CTO PCI, where all patients got optimal medical therapy. All patients had an MRI baseline confirming viability. And then, they looked at segmental wall thickening by MRI in the two different arms. It was really kind of a disappointing, a negative trial, because of a lack of really any significant improvement in MRI proven LV function. One of the criticism of this trial that was made is that the data was derived from patients who never had any proven ischemia prior to the study. So questionably symptomatic patients, so maybe not the right patient population, and also at baseline, most of these patients had a very high ejection fraction to begin with. So not totally sure that this is indicative of the kind of patients that we take care of, but somewhat of a negative trial that you may be hearing about or reading about.
The Euro CTO trial is a 400 odd patient trial done in Europe, the randomized clinical trial randomizing patients to CTO PCI versus optimal medical therapy. They had a very high success rate in this trial of CTO PCI of 86 percent. And they showed improvements in quality of life indicators, as well as angina burden by CCS class. So this is probably the first sort of randomized clinical trial that has shown clinical benefit in terms of quality of life indicators. It's this relatively small study, 400 patients, it's a little bit different than much more high notoriety trial called the Decision CTO trial that was presented at AHA several years ago and only published last year. This is a randomized clinical trial of 834 patients in almost 20 institutions across Asia with stable angina. And they were followed up to five years.
Now, the biggest problem with this trial is it wasn't really a CTO versus medical therapy trial. And this trial now all of the lesions that could be treated that were patent were treated, and then patients were randomized to CTO PCI or medical therapies. So it was really a trial comparing opening every vessel that was openable and then randomizing to CTO PCI versus medical therapy. And they really didn't show much in the way of a difference in the primary composite endpoint, which was all caused mortality, MI stroke, or need for repeat revascularization. And that was the intention to treat arm.
The biggest issue here there was a huge crossover rate, and that's the big challenge that we've faced in this whole scenario is that the genie's kind of out of the bottle. We know that we have patients that we can help clinically with angina. So it's very, very hard to enroll patients in these trials, particularly if they're symptomatic. It's very, very hard to tell a patient, look, we're going to roll the dice, randomize you to medical therapy, versus just sending you to an expert center where this can be opened. And this is something that I don't think we really have a good answer to. And it's really a challenge in terms of how to really enroll patients and get the answer that we're all looking for in terms of a properly run randomized clinical trial.
That being said, where are we now? We obviously have these limitations. We know that there's some clinical benefit for the right patient. So based on that and the clinical scenario that I showed in the beginning, I'm going to go through where we are in the current state of things. What we know is that volume begets success. The more volume that an operator can perform, the more their success, and the lower their complication rate. And that gets this whole issue of high volume centers. So systems like ours, where we can funnel patients to high volume operators who do these on a regular basis, we tend to have better outcomes than the less frequent operator who doesn't do CTO on a weekly basis. And this has led to a very, very high success rate. So our current success rate at the main campus is 88% on a first attempt and even higher on a second attempt. So that that volume is really what begets the success.
And this is some more recent data looking at that same idea. So on the left panel, you can see that the more cases we do, the higher success rate becomes, but it comes at a cost. There is an uptake in major bleeding shown in this trial, and a relatively flat, but maybe a slight uptick, in adverse cardiac event rates. And I think that this is important. I want to show you where this is coming from. So how do we do CTO PCI in the modern era? So obviously you can advance a wire antegrade through a CTO, like what we're showing here. That works maybe 60 percent of the time, but then there's another 40 percent where we had to do much more advanced things like come in retrograde, go into the sub-intimal space and reenter.
These are all unique skill sets. They require that volume and the practice and the ability to do these procedures safely and manage any potential complications. This is an example of going sub-intimal purpose in an LED and using a specialized balloon to reenter the LAD. This is called a stingray balloon. So this has kind of helped to bring up our success rates from that 60 percent that I showed you in the beginning up into the high eighties to 90 percent rate. This is another example of something that we do. So this is a wire in a PDA coming at retrograde through an epicardial collateral into the LAD. this is something that has dramatically improved our success rates, where the antegrade wire is clearly sub-intimal and was not able to progress.
This is an extreme example. This is a patient with a left dominant circumflex that we did here last summer. You can look at how many wires are in here. So we opened up CTO OM1 and got into a jump graft from OM1 into the left PDA and came backwards and fixed the circumflex proper to the AP groove. And on the way out, we fixed OM2. We used intravascular imaging like IVIS to show where our wires are so you can see our antegrade wire, you can see our retrograde wire. We can make sure that everything's in the true lumen. So these are all really specialized tools and techniques that makes some pretty impressive procedures possible, and safely. That's the main thing is that they can be done safely. We didn't share off any branches. We had every branch re-vascularized at the end of the procedure and the patient felt great and is very, very happy.
But all of this comes at a cost. All of this comes at a cost. So this is a little bit older, this data right here, showing up to 3 percent, 4 percent risk of certain complications in this meta analysis. The big dreaded complications are donor artery thrombus, donor artery dissection, gear entrapment. Radiation skin injuries appears to be much less with our modern x-ray equipment, but these are unique complications that we don't really think about with CTO PCI. Now, if you look at open CTO, I talked about open CTO earlier, a 1,000 patient registry done in the US where all the events were adjudicated. They show a much higher complication rate. They show almost a 10 percent rate of complication with a 1 percent risk of mortality. And that's with an 86 percent success rate. So it's a little sobering to understand that with very, very high volume operators, with lots of expertise, 1 percent risk of death.
So the biggest and scariest thing that the open CTO trial showed is that perforations are relatively common, 9 percent, and almost all the deaths were associated with some sort of a perforation. And the other thing that needs to be emphasized is that patients that get through these complications, that survive the complications, tend to have a lower quality of life health outcome score up to 12 months post PCI. So even if we can get them through complication, there is some issues with these patients in long-term follow-up.
Let's put it all into perspective. So the NCDR, if you put the open CTO cohort in the NCDR database, their risk of mortality is around 0.4 percent. And I said that the actual mortality was almost 1 percent. by STS, the open CT cohort mortality should be 1.7 percent. So somewhere in between what our current risk models would recommend or indicate, but look at it in a slightly different way. So we said the open CTO mortality was 0.9. The NCDR vein graph intervention mortality is 1.1. So we do vein graft interventions all the time, and don't think anything about it, yet it has a higher expected mortality in NCDR than open CTO did. So as sobering as it is, I think we need to try to put this all into perspective and understand that in some situations, it's in the patient's interest to at least offer them this type of procedure, because we could give them a meaningful result with a higher than open vessel risk of complication, but maybe not much more than of ingraft intervention.
So where is this complication risks coming from? Most of it's coming from these advanced crossing strategies, like going retrograde. That is strongly associated with these complications, perforating, epicardial collateral, perforating a septal perforator, causing donor artery trauma. These are the things that get us into trouble and that we have to be experts at getting ourselves out of during the procedure. And that sort of dovetails in the work that we've done here at the main campus. So one of my big goals is to, first of all, teach the fellows how to do these procedures so that they can go out and do them, because as I showed in the beginning of the presentation, there's far more patients with symptomatic CTO than there are operators currently qualified to take care of these patients. So we want to train as many physicians as we can to be qualified to do these procedures.
And we also know that the advanced crossing strategies like retrograde and sub-intimal are associated with stronger risk of complications. So is there a way to make antegrade wire escalation more effective? Is there a way to make it safer and more approachable and more applicable to more difficult lesions? There's a term called the JCTO score. It's an anatomic and clinical risk scoring system to determine how difficult a lesion is to cross. Basically a JCT zero should be pretty easy to cross. And a JCTO five is the most difficult type of CTO to cross antegrade. And this is a paper that we actually just got published earlier this month, looking at a new class of guide wires that have been available in Japan and Europe for many, many years, but we only got them in the US back in March of '17.
So we did a prospective look at these wires and their impact on antegrade wire strategy on a US patient population here at the clinic. And what you can see is that an easy lesion, so JCTO zero to one, our success rate just with these wires alone, is almost 80 percent. It starts to drop off as you get into more difficult lesions down to 60% with JCTO two to three, and then only 17 percent in JCTO four to five. So obviously the more difficult the lesion is to cross, the less likely this wire is to work, but in a simple, straightforward lesion, 80 percent of the time, we're going to cross just with one wire in conjunction with a microcatheter like a Coursera to support it. And what's really kind of interesting is that even in lesions that are not predicted to be able to cross, if we do cross, we cross efficiently.
So if you look across this panel down here, the amount of time it takes to it's pretty flat. So it doesn't matter how difficult it is. If we're going to cross, we cross very, very quickly. And this is also true if you look at, there's an algorithm that we use to determine what's the best strategy to use, whether you go to antegrade, whether to go retrograde, whether to go sub-intimal upfront, and that's called the North American hybrid out. And if we look at that, if we decide to go antegrade first, no matter what the hybrid algorithm says, it's the same story. 74 percent, when the algorithm says to go antegrade, and it starts to drop off when the algorithm tells us to go sub-intimal or to go retrograde. But if we're able to cross again, the time is flat.
So what am I trying to say? I'm trying to say that we can use these really safe, soft wires to approach pretty much any CTO. And if it's an easy CTO by anatomy, we're probably going to cross with very high likelihood of success. And if we're going to cross any of them, we cross pretty quickly. So you'll know if you're going to fail very quickly and you're going to succeed very quickly if it's crossable. There's very little to lose by trying. It's a very soft wire. It's not going to perforate anything. Our complication rate was extremely low by doing this. So it's a way to try to bring this down to the masses so that more people can at least get their feet wet in trying to do these procedures and at least approach the easy ones upfront.
For more advanced operators, this is a way to prepare the lesion for what's coming next. We have to have a wire sub-intimally in the lesion anyway. So why not try antegrade to see if we cross. If we don't cross, no big deal, we're going to do all the other advanced crossing strategies anyways, but we have to have a sub-intimal wire in the proximal cap to begin with. So why not just start that way? So this is exciting data that hopefully will get other people interested in at least approaching these lesions upfront. And if you try integrate and it's unsuccessful, then you have a system in place to refer these patients on to a more advanced operator without any real risk to the patient, and no real damage to the lesion to preclude a more advanced crossing strategy in the future.
So this is the algorithm that we use here at the main campus for patients to refer for CTO PCI. The first question is, are you symptomatic? Because if you're not symptomatic, I really don't know that you're the right patient. There are exceptions to this rule. So the question is, is there a significant amount of ischemia if you're not symptomatic? Is your ejection fraction diminished? Do you have a lot of ventricular arrhythmia? Are there special circumstances that would justify CTO PCI? So that's a path that we do take in referral centers for unique patient populations, but the bulk of the patients that we're taking care of are going to the right of this panel, patients who have lifestyle limiting angio on good meds. And then the question is, do you have complex and/or multi-vessel disease? And are you a candidate for surgery?
Most of my patients that I get referred have already had cabbage and they have a patent LIMA, and what they've lost is a vein graft to the PDA or a vein graft to the circumflex. So most of these patients are really not sent for a second operation for a non LAD target. So that's the strongest, I would say, argument to be made for CTO PCI, is that patient who has already had the benefit of the LIMA, who is still symptomatic because one of their vein grafts has failed, and they're on good meds and they're still having significant angina limiting their lifestyle. So that's the ideal patient. And then you can look at the algorithm at your leisure in terms of who else might be a good candidate, but that's sort of the top shelf A-list candidate for one of these procedures.
So in conclusion, I'd like to say that these advanced techniques that we have described briefly in this talk today, they're highly effective. They have acceptably low, but not zero complication rate. And these numbers that I quoted are really only applicable to high volume operators with lots of expertise in the procedure and how to manage the complications. So we need to focus our efforts on selecting these patients that are most appropriate to benefit from CTO PCI. And the biggest thing to understand is if they're not symptomatic, then this may not be the right procedure for them because it comes at a price. There is some risk of complication, and real complication. So if it's not for symptom relief, then we need to understand, is there a significant ischemic burden that we're trying to relieve because of low EF, heart failure symptoms, ventricular arrhythmias?
And then the last thing I'd like to say that most of the data that we have is observational. There is some randomized clinical trial data. Most of it is controversial currently, and there is some real challenges to a proper trial because of the genie being out of the bottle. We know that we can already help these patients. So it's very, very difficult to actually enroll patients in a randomized trial. So it really requires sound clinical judgment, and patient involvement in the decision making.
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