Talking Tall Rounds: Approaches to Complications of Myocardial Infarction (MI)

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.

Aaron Weiss, MD, PhD:

Welcome everybody. My name is Aaron Weiss. I'm one of the staff surgeons here at the Cleveland Clinic. We're here today at Tall Rounds to talk about the Cleveland Clinic approaches to complications of myocardial infarction, but really with a focus on post myocardial infarction, ventricular septal rupture. The first speaker we have today is Andrew Higgins, one of our all-star intensivists, and heart failure physicians, who's going to give us a primer on the preoperative care and the ICU care associated with these complex patients.

Andrew Higgins, MD:

Thank you to Doctors Weiss and Smedira for the invitation. And so I'm here to talk to you today about how we approach these with a specific focus on how we see these in the J31 preoperative and critical care cardiology setting. So thank you for the invitation again. It's no news to anyone in this audience that we're getting progressively better at STEMI care. So led by efforts by Dr. Krishnaswamy among many others, we've progressively gotten better at how rapidly we identify, triage and get patients with STEMI and NSTEMI to the cath lab table, get them revascularized and hopefully improve our myocardial salvage. You can see out of here on the left that we've had progressively shorter door-to-balloon times over the past 30 years, going from an era of almost four hours to around three hours, two hours, and then gradually to the sub-sixty-minute time.

With this, you've seen a gradual improvement in outcomes. And so in addition to the dramatic stepwise improvements in outcomes that we saw with the advent of first fibrinolysis and later PCI, our improvements in how we triage and deliver care, have led to more rapid improvements over the past even 20 years within the PCI era. You can see data here out of Northern Europe on the right.

Unfortunately, these trends are threatened, and so there are still persistent issues that this system faces. And so we're seeing a demographic of patients across the United States, but particularly among STEMI and NSTEMI patients of an increasing age shift, and you can see that mortality remains high across decades of age going from less than 50, to greater than 90, that we're going to continue to confront this, that although we've made progress, these older patients are going to continue to present a significant risk in the peri-MI and post-MI setting.

And moreover, although we've done a much better job about increasing access to PCI, particularly in the urban setting, a lot of the growth in PCI-capable centers over the past 20 years has been driven by urban in-reach rather than rural outreach. And so a significant chunk of the population within the United States still sits outside of that sixty-minute time zone, to the nearest PCI-capable center. And you can see here work from the mid-twenty teens on how much of the country is left uncovered by our first-line primary PCI therapies.

This combination is particularly concerning when you look at our rate of mechanical complications. And so, this combination of an increasingly older population and still a residually high door to bloom time among a significant fraction driven both by our systems of care, as well as delayed presentation, has led to a relatively flat incidence over time. And so although we made significant improvements, again with the advent of fibrinolysis and later primary PCI, we haven't really moved the needle on the incidence of mechanical complications in the past 20 years.

And you can see that that's remained high across both the STEMI and NSTEMI populations. And mortality unfortunately, has remained high in that setting as well. And so, although it's slightly lower for our NSTEMI population than our STEMI population, to have a mechanical complication of your MI is an immediate uptick in your mortality. And so, we're seeing a STEMI mortality of around 40% in association with a mechanical complication, and an NSTEMI mortality around 25%.

So Doctors Tamis-Holland and Menon in the back there, were key authors in this critical document in Circ a couple of years ago on the scientific statement on management of these mechanical complications. And so, you can see their table on the right here summarizing some key findings about when they present notably late, several days after the initial infarct, and that's why it's so critical to tease out really when these symptoms started, and that really begins in that first phone call with the outside hospital.

It's important to note that the majority of these cases don't come from within our ED at main campus, that we're seeing these patients coming in from the region. We're seeing these patients coming in from outside hospital. They may have already had a delayed presentation of several hours or several days, but between their initial onset of symptoms, and when they finally sought medical care, the additional door-to-device time from there, and then they're coming to our attention sometimes a day or two later, after their initial revascularization at an outside hospital.

And so, they're coming in often through our STEMI pathway and often not. And so it's critical to keep in mind that ideally, these have been recognized triaged, and you're being notified of a patient when they're already aware of a mechanical complication. But, it's critical to maintain a high index of suspicion anytime you hear those risk factors. And so, when we're getting on the line, and we're talking about our shock patients, anytime you're seeing a cardiogenic shock patient with an atypical history in the preceding few days, when you're seeing cardiogenic shock, with out of proportion to the extent of their left ventricular dysfunction, you have to maintain a high index of suspicion for this. It's classically three to five days post-MI the initial echo, particularly if it's obtained in a system that does a lower volume, maybe it's subtle or non-diagnostic. And you have to really be aware when you're seeing these older patients with a delayed presentation, patients who have a history of baseline heart failure, patients who have a history of baseline renal dysfunction, these are the patients that are going to set you up for late detection of this. And then that's when you really get into trouble.

On that initial phone call with the outside system, it's also important to triage the extent of end organ dysfunction that they've already encountered, because they may have smoldered for a little while there before that initial transfer. And it's important to get a sense for how coagulopathic they are, and keep in mind that they often were just revascularized at an outside system, and may be on relatively intense antiplatelet therapy still with Prasugrel or Ticagrelor. And so it's important to get a sense for that because it may inform or even constrain our surgical options, depending on how bad their bleeding may be.

The next step, again, while we're still on the initial phone call, is defining the severity of illness. And so, how much vasoactive or temporary mechanical support are they on there, and how much are they going to need to be on to get here in a safe fashion? There's a lot of variation even within each pathology on how sick these patients are. Is this a patient who has a relatively small restrictive VSD, that came in a few days late, that has some degree of left or right shunting, but it's not torrential. You can medically manage them, get them into an ambulance, get them over here in a calm fashion, talk about medical stabilization and an urgent but not emergent surgical repair. Or, is this someone with a massive VSR with just a torrential left or right shunt when really time is of the essence, and you don't even know if you're going to be able to get them into the helicopter and get them here safely, or if they need to go on some support there. That in turn leads to a conversation with the regional hospital, or the outside hospital, about what they can do there, what they're comfortable doing there, and how much that's going to delay your transport. And I think that's a critical conversation, because sometimes you're on the line and you desperately want to get the patient here, but you know that they're just not safe to get into the helicopter, or in the ambulance, and get to you. And that can be a really stressful and heartbreaking conversation.

There is no good evidence to guide us in this setting. So unfortunately, mechanical complications of AMI have been systematically excluded from every major cardiogenic shock trial. And so, going back to the original shock work with Judy Hochman, looking at the importance of timely revascularization in cardiogenic shock, complicating acute MI, looking at IVP Shock 2 for balloon support, looking at ISAR-SHOCK, looking at ECLS-SHOCK, looking at dangerous shock. All of these trials systematically excluded patients with a mechanical complication of their AMI, and for good reason. They're sick patients with complex decision-making in the days that are going to follow that initial deployment of TMCS, and you can really lead them astray by making the wrong decision in those first few hours. And they didn't want to muddy data in these larger series by including this relatively heterogeneous population, but always treating patients with TMCS and cardiogenic shock is a relatively evidence light zone, but this is truly an evidence-free zone, and that's why it's been so great having the shock team available to have these conversations in a multidisciplinary fashion, early in the course of the patients transfer. And so, even before they're leaving the outside hospital, we're triaging how sick they are, having a conversation between heart failure, intensive care, cardiology, our colleagues and intervention, cardiac surgery and anesthesia, all on the line simultaneously, to talk about how can we stabilize them there, how can we get them here? And then once they get here, what can we do for them?

On arrival to the CCU, the first thing is just taking a bedside assessment of what their peripheral hemodynamics look like. So, what's their MAP like? How much support are they on? Take a look at their respiratory status, because it's often been temporized, but maybe not definitively addressed. And getting these patients onto non-invasive, or invasive mechanical ventilation can actually have a significant physiologic benefit. The increased work of breathing and the negative inter-thoracic pressure that generates, can have deleterious effects both on the pulmonary edema associated with pap muscle rupture as well as on the left or right shunting and association with VSR. And so, you can buy some time if you have the MAP to do it, getting them onto non-invasive or intubated.

Get them echocardiographically and right heart cath phenotyped as soon as possible. And so, I think this is a critical action and it can happen contemporaneously with your initial medical stabilization. So, if VSR is suspected and the diagnosis is not already secure, then do a shunt run on your initial right heart cath. It takes five additional minutes. You're already there. You can be stabilizing them while you're getting this rolling. If you need vasopressor support, then you're committed to it. And so, there's no good evidence on what vasopressor to reach for in this context. I'd say we reach for norepinephrine most commonly. If you have the MAP room to tolerate it for both pap muscle rupture, and for VSR, then consider a trial of nitroproside. It'll diminish your shunt. It'll make significant improvement in your pulmonary edema, but again, if your MAP allows.

There's no real evidence for inotropic support in this context. And so it's important to keep in mind that these patients are either actively or very recently ischemic, and adding inotrope to that milieu can be really dangerous. And these patients are already quite tenuous. And so if anything, the ventricle is often bordering on hyperdynamic because it's seeing the acute afterload reduction from a sudden MR, or from the presence of a left or right shunt. And so, you don't usually need inotropic support as much as you need afterload reduction in some form. And so, I think about putting a balloon in these patients early. It's not enough support for a significant chunk of the patients. It also doesn't delay things very much. And so, while we're talking about getting them onto more definitive support, or getting them into more definitive repair, you can do an 8 French arteriotomy and it takes 15, 20 minutes, and it can buy you time until you can get them to something more significant.

Early in the CICU course though, I think it's also important to start talking about how we define this trajectory for these patients. And so, this is an older, sicker, frailer population, with more comorbidities. And I want to know early on from the patient and from the family, how functional they were previously, what their family support is like, and give them a sense for what I think their myocardial trajectory is going to be, separate from addressing the mechanical complications.

So, is this someone who had an EF of 15 to 20% baseline, who took a big anterior wall hit? They're coming in with a VSR a few days later, in the context of inadequate revascularization, and we're really going to be struggling with that, and we need to be talking about either definitive therapies with that, or transplantation, or moving towards palliation and addressing that VSR isn't going to be enough, and I want to know how much their other end organs have been compromised in this setting.

And so am I seeing a severe AKI? Am I seeing an ischemic hepatopathy? Was there downtime in the context of this? Is there neurologic injury? All of this really informs their prognosis, and I think it's critical to define this early in the course with the family, because the road to recovery's going to be challenging for them. Not that any coronary event is ever simple, Dr. Krishnaswamy, but it's become much more than just a coronary event.

And so, sometimes they're not in for that, and I think it's important to find that out and get a sense for how functional they were, whether they would want these incredibly life-saving critical, but very challenging measures to get through, and I'd much rather find out that they're in for this, or not in for this, on pre-op day one, than post-op day zero when I find out that, "Oh, they never would've wanted this in the first place," and then we're having a very difficult conversation.

So to recap, mechanical complications remain an issue. STEMI outcomes are steadily improving, but our outcomes for mechanical complications are lagging a little behind. Maintain a high index suspicion, particularly in the context of a delayed presentation. MOF is often present, and the optimal timing for how we support these patients and repair these patients definitively, is sometimes unclear. So it's very much a team sport. And maintain your open lines of communication. Thank you.

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