Mechanical Thrombectomy for Stroke

Additional Info

• Audio File:uab/ua155.mp3
• Doctors:Liptrap, Elizabeth;Lyerly, Michael
• Featured Speaker:Elizabeth Liptrap, MD | Michael Lyerly, MD
• CME Series:Clinical Skill
• Post Test URL:https://cmecourses.som.uab.edu/mod/quiz/view.php?id=4143
• Guest Bio:Dr. Elizabeth J. Liptrap grew up in Maryland and received a B.S. in Biochemistry and Molecular Biology from the University of Maryland, Baltimore County (UMBC). She received a medical doctorate from the University of Maryland School of Medicine in 2011. 
  
  Learn more about Dr. Elizabeth Liptrap 
  
  Michael Lyerly, MD is an Associate Professor (P), Neurology , School of Medicine 2013 -. 
  
  Learn more about Michael Lyerly, MD 
  
  Release Date: August 18, 2020
  Expiration Date: August 18, 2023
  
  Disclosure Information:
  
  Planners:
  Ronan O’Beirne, EdD, MBA
  Director, UAB Continuing Medical Education
  
  Katelyn Hiden
  Physician Marketing Manager, UAB Health System
  
  The planners have no commercial affiliations to disclose.
  
  Faculty:
  Elizabeth J. Liptrap, MD
  Assistant Professor, UAB Brain and Tumor Neurosurgery
  
  Michael J. Lyerly, MD
  Associate Professor, UAB Neurology & Vascular Neurology
  
  The planners have no financial relationships related to the content of this activity to disclose.
  
  There is no commercial support for this activity.
• Transcription:Introduction: UAB Med Cast is an ongoing medical education podcast. The UAB division of continuing education designates that each episode of this enduring material is worth a maximum of 0.25 AMA PRA category one credit. To collect credit, please visit UABmedicine.org/medcast, and complete the episodes Post-test. Welcome to UAB Med Cast, continuing education podcast for medical professionals, bringing knowledge to your world. Here's Melanie Cole.
  
  Melanie Cole: Welcome to UAB Med Cast. I'm Melanie Cole and today we're discussing mechanical thrombectomy for stroke. Joining me in this panel discussion are Dr. Michael Lyerly. He's a Neurologist in Vascular Neurology and an Associate Professor at UAB Medicine and Dr. Elizabeth Liptrap. She's a Neuroendovascular and Vascular Neurosurgeon and an Assistant Professor at UAB Medicine. Doctors, I'm so glad to have you on today and what an exciting topic so much happening with mechanical thrombectomy. Dr. Lyerly, I'd like to start with you, if you would explain a little bit about prehospital management and field treatment, tell us what's important as far as latest clinical guidelines for stroke.
  
  Dr. Lyerly: Absolutely. As I think a lot of people are aware, stroke is a highly time sensitive diagnosis that it really starts with detection in the field by either the patient or a bystander. And having that patient quickly entered into a stroke system of care by way that they can get access to a hospital as quickly as possible. Right now we don't have any treatments that we can offer somebody who is having an acute stroke in the field because the first step that really has to be done is they have to get to a hospital quickly so that they can undergo imaging studies, usually with a non-contrast head CT scan. As we'll talk about, we're doing more studies now to further investigate that and have expanded our diagnostic studies once the patient gets to the hospital, but really there's not a whole lot going on in terms of treating the patient in the field yet right now. Where things are starting to evolve is with mechanical thrombectomy, not every hospital is able to offer that therapy.
  
  And a small proportion of patients who are having an ischemic stroke would benefit from getting to a hospital that has these capabilities of treatment. And in order to do that, what's being done in the field now is trying to better triage a patient, which means determining what type of stroke that they might be having. If the stroke is severe enough that they may be having a stroke because of a large vessel occlusion, and then determining what's the optimal hospital for them to go to. Once they get to a hospital that is able to offer endovascular care, we're starting to do more multimodal imaging now, including CT angiograms and CT perfusion scans in order to identify if the patient does have evidence of a large vessel occlusion. And if so, if there is salvageable brain tissue, that might be a minimal to a reprofusion therapy.
  
  Host: Well thank you for answering a question I was just going to ask about brain and vascular imaging and what's new and exciting. Dr. Lyerly sticking with you just for a minute. What is new and exciting as far as vascular imaging?
  
  Dr. Lyerly: Well, these studies are not new studies per se, it's that we're using them for a new application. CT angiograms and CT profusion scans have been around for years if not decades, but what we're doing now is we've learned that when using CT profusion scans, we can more reliably determine what area of a brain that is having a stroke has irreversible damage versus what area potentially has salvageable tissue. Many of our listeners may have heard the term penumbra before, which basically means an area of brain that has become stunned, but not necessarily irreversibly damaged because of lack of blood flow. And that's really the name of our game is trying to identify what area of the brain can we potentially save. And that's what the CT profusion scan is offering for us now. Another new development is we have a new processing software in the past. It was quite an undertaking to process the images from a CT perfusion scan, particularly in a timely manner, to be able to return them to a clinician, to make a timely treatment decision. Now, we have computer automated algorithms that can rapidly interpret the images that come through and provide those images in a very easy to understand color map, to help a clinician make a quick treatment decision to determine is this a patient that we should be taking to the catheterization lab.
  
  Host: And before we discuss the use of endovascular interventions, Dr. Lyerly tell us about the use of TPA and its implications for rapid response treatment
  
  Dr. Lyerly: Right. Right. So TPA or Alta place has been really the mainstay of acute stroke treatment. And when we're talking about stroke, we're talking about ischemic stroke. This has been around for a little over 20 years now. So we have quite a bit of experience with it. TPA is a clot busting medicine that can hopefully restore blood flow to an artery that is blocked off. Although the benefit really only helps about one in three patients. So a large majority of our patients still don't receive the full benefit of recanalization after they receive Alta place. There are some downsides to the medication, including risk of hemorrhage or an Anaphylactic reaction, but it right now remains the only FDA approved medication for somebody who's having an acute ischemic stroke. So that's been our mainstay treatment and all that we've had to offer a patient, but over the past decade, as we've seen more and more patients coming in with very large strokes, particularly due to large blood clots, we've realized that TPA is just not going to be enough that medication can start to eat away at the end of a clot. But at the end of the day, it's very unlikely to be able to dissolve a large blood clot that causes a large vessel occlusion. And so for those patients up until several years ago, we really have not had much that we can offer those patients. And that's really where mechanical thrombectomy comes in as a new option that we can use to treat these patients
  
  Host: Dr. Liptrap onto you. So tell us about the use of those endovascular interventions, such as mechanical thrombectomy. What are the latest clinical guidelines for indications for use?
  
  Dr. Liptrap: So the latest clinical guidelines are that patients can be treated sometimes up to 24 hours. As Dr. Lyerly had mentioned previously regarding the use of the CT angiograms, CT perfusion scans, and the software that can rapidly process that imaging that has helped us identify patients who although they presented later could potentially benefit from thrombectomy. In the past, it was thought that, you know, patients could be treated if they presented within six hours of symptom onset, but there've been new clinical trials that showed that certain subsets of patients, if they have favorable imaging showing that there is a decent amount of brain volume to be saved, could benefit from mechanical thrombectomy. So you know, Dr. Lyerly or someone from his team will often contact us letting us know that there's a patient, who's a potential candidate. And once the patient is in the hospital, then we assess the patient together. And often they'll undergo vessel imaging and possibly profusion studies to determine if the patient's a candidate. And then sometimes we'll have the patient be intubated if needed, prior to the procedure. And then we'll take the patient to our angio suite where we have a team that that is either already in the hospital or, you know, within 30 minutes of the hospital. And will take the patient for the procedure then.
  
  Host: Well, Dr. Liptrap, tell us a little bit about patient selection and why that's such an important aspect of this? Is this treatment for everyone who's had a stroke or are there certain patients for whom this is not an option?
  
  Dr. Liptrap: Yeah, that's a good question. So the reason why there had been the time limit in the past was the thought that, you know, after six hours or a certain timeframe, the amount of brain tissue that was going to be damaged by the vessel occlusion would be you know, completely gone. And so if there is no brain that can be saved, it's not worth putting the patient through the risk of the procedure, because, you know, as with any procedure, there are risks involved. You can have injury to blood vessels. Once the blood clot has been taken out. Sometimes there can be bleeding into the damaged brain tissue. And while the procedure is often you know, can be beneficial. There certainly are risks and we don't want to put the patient at risk if there's not going to be a benefit.
  
  Host: Well, tell us a little bit Dr. Lyerly of the benefits of this treatment versus other treatments to the patient and to the provider.
  
  Dr. Lyerly: As I mentioned Alta place or the TPA, the clot busting drug is really only effective in about one in three patients. Mechanical thrombectomy originally had some good data, but the more studies that have been done, the more we've actually seen some pretty phenomenal results come out of it. We've seen numbers upward of the mid to high 80% of patients actually getting that blood vessel completely reopened that doesn't necessarily always translate to a clinical benefit just because we can get a blood vessel open. If damage has already been done that may not translate to meaningful clinical improvement for the patient, but the studies that have been done with these procedures have actually shown that a large majority of the patients who undergo the thrombectomies do have a favorable outcome, meaning that they either get back to normal, or they're leading a near normal, independent life. And that's something that we've not been able to offer these patients in the past.
  
  Dr. Liptrap: And that is very exciting that those statistics, but then also even for the patients who don't necessarily clinically improve a lot sometimes just taking out the occlusion can prevent a patient from having life-threatening swelling of the brain that can sometimes come with strokes. And so you know, we found, you know, a number of benefits that maybe weren't even realized previously with thrombectomy.
  
  Dr. Lyerly: And if I can just add one additional thing, a lot of times in medicine the benefit that a patient may receive is measured or reported in clinical studies as the number needed to treat. The number of patients that must receive a treatment or a therapy in order to benefit from it. And the number needed to treat that we found with some of these procedures is sometimes just under three patients and looking at other therapies that are out there in medicine. That's a pretty phenomenal number to be able to see something that low, that just treating a few patients will result in at least one of them having a significant benefit with returning to either a completely normal or near normal functional status. In the past, if we were not able to offer that treatment to the patient, the likelihood of them returning to that level of functioning was probably less than 15 to 20 percent
  
  Host: Dr. Liptrap, does it require a learning curve, are all institutions doing it now for select patients?
  
  Dr. Liptrap: The procedure certainly does have a learning curve. People who perform mechanical thrombectomy for stroke are typically neurosurgeons, a radiologist or neurologist who've had specialized training. And you know, these doctors go through residency and then often go through fellowship or a number of fellowships to be able to do the procedure. And so not all institutions have the capability of performing a thrombectomy. And so that's why patients will often be transferred to a facility that can, so, you know, for instance we at UAB get patients transferred to us from a number of facilities so that we can potentially offer them this treatment.
  
  Host: Dr. Lyerly before we wrap up, give us your final thoughts on referring physicians to a designated stroke center, such as UAB Medicine, why you feel that's so important and what you'd like them to know about any exciting advances in stroke treatment.
  
  Dr. Lyerly: So I think right now we're seeing more and more specialization of different hospitals offering different treatments and different levels of care for stroke patients, including certification levels of primary stroke centers and comprehensive stroke centers. It's been fairly well established that patients who undergo care at a certified stroke center of any type have better outcomes and are more likely to be put on correct medications to reduce the risk of having another stroke in the future. The comprehensive stroke center designation means that the hospital is able to provide 24/7 endovascular care as well as access to neurologists, neurosurgeons and neuro critical care physicians. So they really get the whole package of stroke care. And so one message here is that it's better for the patient in their best interest to be referred from a community hospital to a stroke hospital so that they can get that comprehensive level of care throughout their hospitalization.
  
  Furthermore, these hospitals also have designated areas within the hospital called stroke units, where the nurses are particularly well-trained in stroke care and neurological assessment, as are all of the therapists. And so that's why it's very meaningful to get a patient to a certified stroke program so that they can receive this care. What is new is obviously where we are with this thrombectomy. And I think most physicians have become pretty accustomed to the time windows that we have for using Alta place up to four and a half hours. But the knowledge about the time windows for endovascular care are, have just not been well disseminated down to the community yet. So we still see a lot of hesitation among referring physicians to get a patient to a stroke center in a timely manner, because may not be aware that we do have additional therapies that we didn't have even five years ago to offer these patients.
  
  Particularly as Dr. Liptrap was explaining, using profusion imaging to select a patient even up to 24 hours, is something that really has only come about over the past two to three years. And certainly we want to be able to get to those patients as quickly as we can. And so, for me, that has been the biggest thing that has happened in stroke. We've gone from being able to only take care of a patient out from a few hours from when their symptoms have started. We're now able to potentially take care of patients 24 hours, which five years ago, people thought was completely unheard of.
  
  Host: Dr. Liptrap, last words to you. What would you like referring physicians to know about some of the exciting advances and mechanical thrombectomy and why they should refer to UAB?
  
  Dr. Liptrap: But at UAB, we do 150 to 200 and we're on track to do, you know, even more stroke cases per year. So we have a lot of experience. And we've got great Neurointerventionalists here Dr. Harrigan, Mark Kerrigan and Dr. Jesse Jones are both my partners and they're excellent. We have a great relationship with our neurologist and our neuro critical care team. And so we all work very well together to provide the most comprehensive care for the patient. Regarding mechanical thrombectomy itself, there are currently you know, a number of techniques we use to try to get the clot out, whether it's aspiration, stent retrievers, which kind of grab the clot and help you pull it out and flow reversal to aid in the removal of the clot. And neuro interventional radiology is a field where there are advances happening pretty much every day with new catheters, new techniques, and you know, at our group, we like to stay on the cutting edge of what the most you know, most current treatments are. So it's a very exciting time. And you know, in the future, I'm sure that we're going to just be able to improve outcomes for patients.
  
  Host: Thank you Doctors, so much for coming on and sharing your incredible expertise. It is an exciting time in your field. And thank you again for joining us. A community physician can refer a patient to UAB Medicine by calling the MIST line at 1-800-UAB-MIST. And that concludes this episode of UAB Med Cast. For more information on resources available at UAB Medicine, please visit our website at UABmedicine.org/physician. Please remember to subscribe, rate, and review this podcast and all the other UAB Medicine podcasts. I'm Melanie Cole.
• Hosts:Melanie Cole, MS