Cardiogenic shock is challenging to treat, and traditionally results in poor outcomes. Therefore, it is critical to identify such patients early and treat them effectively. The National Cardiogenic Shock Iniative (NCSI), started in Detroit, uses an algorithm to manage patients with acute myocardial infarction cardiogenic, while emphasizing prompt triage and treatment.
In this interview, Drs. Manish Kumar (University of Connecticut), and Kayla Riggs (UT Southwestern) of the CardioNerds spoke with Dr. Ivan Hanson (Beaumont Hospital) about the recently published SCAI SHOCK Classification in Acute Myocardial Infarction Insights from the National Cardiogenic Shock Initiative, and its significance in the fight against cardiogenic shock.
Dr. Manish Kumar: Hello everyone. My name is Manish Kumar. I’m one of the third-year cardiology fellows at UConn, and I’m going into critical care as a part of my next step in my training. I represent UConn in the CardioNerds family, and I have Dr. Hansen and Dr. Kayla Riggs from UT Southwestern with me.
Dr. Kayla Riggs: Hi everyone, my name is Kayla. I am a current second year cardiology fellow at UT Southwestern in Dallas, Texas, and I serve as the CardioNerds ambassador for our fellowship. We have the pleasure of introducing Dr. Ivan Hanson, an interventional cardiologist in Royal Oak Michigan, an associate program director of the cardiology fellowship. He’s at Beaumont Hospital. Dr. Hansen is an expert in caring for critically ill cardiac patients, and he recently published the SCAI SHOCK Classification in Acute Myocardial Infarction Insights from the National Cardiogenic Shock Initiative. We are so excited for this collaboration between CardioNerds and SCAI SHOCK 2022, with mentorship from Dr. Truesdell to be interviewing Dr. Ivan Hanson.
Dr. Manish Kumar: Dr. Hanson, thank you so much for your time. The SCAI SHOCK classification was released in 2019 to classify cardiogenic shock into different categories, based on clinical hemodynamic and the laboratory values. When you looked at that classification initially, what were your thoughts, and how did you go about designing your own study?
Dr. Ivan Hanson: Well, first of all, Manish, I just want to thank you and Kayla for the opportunity to speak to you today. Also, thank you to Dr. Truesdell for the invitation, and it’s a real pleasure to be able to talk about this with you guys.
Cardiogenic shock, especially as it relates to acute myocardial infarction, has really been a difficult problem. You probably know that historically, the survival rate has been really poor, and it hasn’t really changed much over the last few decades. There was a major unmet need for ways to identify these patients, and to be able to treat them in a timely manner. And so, when SCAI released the algorithm, the SHOCK Staging, it sort of opened our eyes to the fact that cariogenic shock is really not a binary diagnosis. It’s a spectrum of a lot of conditions within the umbrella of cariogenic shock, ranging all the way from patients that really don’t have what we would consider cardiogenic shock yet, but are right on the cusp of slipping into it, all the way to your patients who are in extremis who have incessant cardiac dysrhythmias, incessant cardiac arrest, and are going to die unless something can be done, and everything in between.
I was privileged to be able to participate in the National Cardiogenic Shock Initiative, which was started at Henry Ford Hospital in Detroit, Michigan, with Bill O’Neill and Babar Basir heading that up. It started really, as a local initiative just in the metro Detroit area, which is now spread too nationwide, and even globally now. And what the NCSI did is, it proposed an algorithm for management of these acute MI cariogenic shock patients that emphasized early triage to the cath lab, early hemodynamic evaluation, and early mechanical circulatory support. Even before the culprit artery occlusion was opened.
We showed in our study, that we had higher than expected survival rates amongst these patients. So, we thought it was a really good opportunity to look at best practice care in acute MI cariogenic shock, and how those patients would fall in the SCAI SHOCK Stage, and what, if anything, we could demonstrate amongst those patients in CSI. So, we were looking at that specific subset of patients. So, we thought, here are two advancements in the treatment of cardiogenic shock, both the SCAI classification and the NCSI algorithmic approach to managing these patients. And so, we wanted to see what would happen if we intersected these.
Dr. Manish Kumar: Yeah. Thank you. It’s been open, I went through the results of your study, and I did look at the initial studies, and I think the results were very clear, as you said, that the outcomes were higher than expected. And then I think, as then you guys went on and did the study with the results that we have today.
Dr. Kayla Riggs: Another question, when were patients initially assigned to SCAI Stages at the time of initial presentation in the emergency room, or after device placement and revascularization?
Dr. Ivan Hanson: In the study, because it was an acute MI study, the most common scenario was, a patient was treated as expeditiously as possible, and then enrolled in NCSI. So, all of these patients had an Impella, prior to staging them in the SCAI SHOCK Stage. So according to the SCAI SHOCK Stage, if you have a mechanical circulatory support device in place, then you are at least a Stage C. So, in this study only Stage C, B, and E were included.
Dr. Manish Kumar: Dr. Hanson, your cohort had about 45% of the patients that came in with cardiac arrest, and the survival was overall about, I believe around 70%, which is better than what has been known from the contemporary trials. Do you think one of the reasons of such a good outcome was that you used early mechanical circulatory devices, or was there something else?
Dr. Ivan Hanson: I think early MCS played a big role in that. But I think beyond that, I think an algorithmic approach to the care of these patients really resulted in the outcomes that we saw. And that includes early MCS, but it also includes immediate triage to the cath lab. Most of these patients had ultrasound guided femoral access, using a micropuncture needle, and placement of a Swan-Ganz catheter. And then of course, the MCS support before revascularization, which is critical.
And so, all of that combined, I think, is what distinguished these patients from, shall we say, the current standard of care. So, these were what we would consider best practices. And so, I think, that was the real reason why these patients did so well.
Dr. Kayla Riggs: Thank you for sharing that algorithmic approach that hopefully we’re advancing toward. But given emerging data and trials, do you think that survival in patients with Stage E could have been improved by moving to VA-ECMO sooner, or other support options?
Dr. Ivan Hanson: Well, it’s interesting that you mention Stage E shock, because in our study, even Stage E patients that were Stage E on presentation did much better than you would expect. So again, Stage E, these patients are in extremis, they’re acidotic, they’re on multiple pressors usually, and they’re progressing toward multi-organ failure.
In our study we showed that 50% of those patients still survived. What really made the difference in survival for them was at the 24-hour mark. Once they were rest staged, those patients that were still in Stage E only had a 20% chance of survival. So, we still have an opportunity early on to salvage these patients. And so, the first point I wanted to make was, just because someone is Stage E at presentation doesn’t mean that all hope is lost.
But to answer your question, we had a relatively low proportion of patients that were escalated, in terms of their mechanical circulatory support, beyond Impella CP or Impella 2.5, which, as you know, provide up to three and a half liters, generally, of forward output. Some patients in our study, but very few, were escalated to an Impella 5.0, which gives you five liters of flow. Some to a 5.5, which gives you five and a half liters. And some to ECMO, which gives you full support, up to potentially seven liters of flow.
Some patients also received an Impella RP, which can support the right ventricle. And so, we didn’t have, our study wasn’t powered to look at the effects of those additional circulatory support devices. And studies are ongoing, looking at escalation of care beyond Impella CP, which is usually the go-to strategy for supporting these patients. But it is an unmet clinical need right now that, we do have some patients that just the standard appellate catheter just simply is not enough. We don’t have the data yet to say that ECMO is better for those patients, or just a more powerful Impella catheter. With each of those devices, there are challenges and potential harm from those devices. For example, vascular complications are quite common with ECMO, because of the relatively large cannulas involved. So, to summarize, I’d say more data is needed.
Dr. Manish Kumar: Dr. Hanson, the results of your study in somebody sort of shows that the initial stages predict their outcomes at presentation and at 24 hours. How do you take these results and incorporate these into clinical practice? Or for example, when you see a patient, what kind of discussions you have with the family, in terms of prognosis?
Dr. Ivan Hanson: Well, that’s an excellent question, and it’s obviously, a complex dynamic assessment. It’s not just a snapshot in time for defining how a patient’s going to do. And for the purposes of this study, we could only capture two points in time, at presentation and at 24 hours. But in reality, it’s a spectrum of ebbs and flows, and you hope that the patient continues to improve. And I guess, my takeaway from our data is that, at baseline, it’s really too early to tell a patient’s family that they’re not going to survive. And at 24 hours, you have a much better idea, especially those Stage E patients, that only 20% of them will survive. And so, I think that gives us, that empowers us as providers, to at least give the patient’s family a realistic expectation.
And I think also, the SCAI SHOCK Stage and all of the variables within it, are just a reminder on best practices. That we should be checking things like cardiac power output, which is a hemodynamic measure that’s easily derived from a Swan-Ganz catheter, but surprisingly, not that often used in the community. But it has remarkable predictive value for prognosis. Things like checking a blood lactate level, which again, falls into the algorithm and defines what shock stage a person is. Things like that are easily obtainable but could be overlooked in the care of these patients. And so, another benefit to the SHOCK Stage is that it really informs us on what we should be looking for.
Dr. Kayla Riggs: Thank you for helping advance how we can care for our patients and talk with our patients’ families about their prognosis. That’s really important to keep the families involved, so they’re understanding.
Cardiac critical care is a rapidly expanding field. Where do you see the future research going when it comes to management of cariogenic shock, and what are the challenges you foresee?
Dr. Ivan Hanson: That’s a really critical point, and one of the issues we’ve had with research in this area is that most centers use a certain strategy, or a certain circulatory support device, and have very little experience with other devices. And so, creating a randomized study of these devices would be challenging, because the level of expertise and the level of comfort for providers using all these different tools is variable. And so, it’s really challenging. So, I’m not sure we’ll have any definitive randomized controlled data that any one of these devices is superior. So, I think, there will be an element of art in caring for these patients, not just pure science. We’re trying to advance that science, but as I allude to earlier, with these devices comes a lot of potential harm, especially in inexperienced centers. Because they are large devices, patients will often have small access vessels in the femoral artery, the axillary artery, especially since those patients are often on vasopressors, which shrink the size of the artery even further, we run into problems with limb ischemia and devices.
Device development toward smaller and smaller devices is really desperately needed right now. And so, I know devices are being developed that are going to be smaller and less obstructive to blood flow. I think we also need better ways of establishing prognosis, beyond what we have. And what we have is good, but we need more biomarkers. There’s a lot of variability, even with things like cardiac power output, like I mentioned, blood lactate levels. Patients can have a normal blood lactate level and still do poorly. We don’t understand all the reasons why, and maybe having different biomarkers will be more predictive. So, I think, there’s a lot still to be learned and developed in this area. And I think, my hope is that we can see survival rates that are beyond 70%, like we demonstrated in our study, but maybe into the 80, 90% range. That would be wonderful if we could achieve those survival rates.
Dr. Manish Kumar: Well, thank you, Dr. Hanson. And as you mentioned, this is a rapidly expanding field, and hopefully, with ongoing research, we should be able to shed some more light into the pathophysiology and may be able to help our patients better. Congratulations once again on your study and thank you so much for your time to provide deep insights into your study and the ongoing research.
Dr. Ivan Hanson: Thank you very much for having me.