Transcription:
Cryptogenic Strokes

Prakash Chandran: Most of us know that an ischemic stroke is typically caused by a blood clot affecting the flow of blood to the brain. But what has it meant when a doctor defines a stroke as cryptogenic? We're gonna learn all about it with Dr. Neel. Khanna the medical director of the cardiovascular Institute at Montefiore Saint Luke's Cornwall.

This is Doc Talk the podcast from Montefiore St. Luke's Cornwall. My name is Prakash Chandran. So Dr. Khanna really great to have you here today. Thank you so much for your time. I wanted to get started by asking or understanding, just tell us what are the most common types of strokes?

Dr. Neel Khanna: So the most common types of, strokes are ischemic strokes where there's lack of blood flow to the brain. Typically in America, the number one cause of that is actually small vessel disease caused by high blood pressure. So basically people have really high uncontrolled blood pressure for many years, and it slowly causes the closing of the small blood vessels in the middle of the brain, primarily that can cause major effects. That's the number one kind of ischemic strokes. And then of course blood clots and pieces of plaque that can break off from the heart or the carotid arteries can also cause other types of larger ischemic strokes.

Prakash Chandran: Okay, understood. And I also know that there is that hemorrhagic stroke as well. is that correct?

Dr. Neel Khanna: Yeah, hemorrhagic strokes is a totally different type of stroke in which there's actually a bleed in the brain that inhibits function of certain parts of the brain. These can be very dangerous, like all strokes, extremely life threatening emergencies, and typically they present with more dramatic immediate symptoms such as severe headaches. But brain bleeds are totally different in that there's not a lack of blood flow to the brain. Actually there's either a ruptured vessel or because of high blood pressure, small little capillaries in the brain that start to bleed.

Prakash Chandran: Okay. And traditionally, at least to my knowledge, ischemic and hemorrhagic are the two strokes that I've heard about most often. This is the first time I'm hearing about cryptogenic strokes. Can you explain at a high level what they are?

Dr. Neel Khanna: Yeah. So cryptogenic strokes is basically an umbrella term for. Your physician saying that they don't know exactly what the cause of your stroke is, which some numbers estimate is as high as 70% of strokes that present to the hospital. It's probably closer to 40 to 50%. But we're talking about half the people who come in with symptoms that sound like a stroke and even imaging like CT scans and MRIs of the brain to show that there has been a stroke that we're not able to.

A number one reversible cause meaning there was no brain bleed seen on imaging on the CT scan or number two, that there is no major blockage in the arteries that go to the brain. And there's no major source of a clot or a piece of plaque from the heart that we could identify. So we're left with a patient who's had a stroke, but we can't find a direct reversible cause of that. So we've labeled those types of strokes, cryptogenic strokes.

And often these are young patients sometimes even younger than 30 years old, who they come in with a stroke, like symptom and their arteries are pretty clean. And so, their medical staff that are taking care of them are a little confounded in terms of what's going on. And modern day research has shown that there's very specific ways to identify and treat these patients.

Prakash Chandran: I there's a couple things that I wanna understand. The first thing is you said upwards of 70% of strokes could fall under the umbrella term cryptogenic, is that correct?

Dr. Neel Khanna: I mean, different analysis have given different numbers. I think the number is far less than that. It's probably, 40% of strokes, 40 to 50% of strokes. I know at our local hospital, we were going over the data recently and it's probably around 30 to 40%, but which is still a large number of strokes that, yeah. That we have identified as cryptogenic, meaning that there was not a reversible cause that we could see.

Prakash Chandran: Got it. And I know you, mentioned reversible a couple times, and the reason why this is important is for an ischemic stroke, for example, up at the top, you were talking about small vessel disease caused by blood pressure. And in order to potentially reverse that you would kind of get your diet in order there are things that you can do. But for these specific strokes that reversibility or the things that you might do to avoid it are just unclear. Am I understanding that correctly?

Dr. Neel Khanna: Sure exactly. For small vessel strokes, for example, that we deem that are due to high blood pressure. We have to really get the blood pressure in order with medications, diet, exercise and risk factor management. For cryptogenic strokes. What we're basically saying is we don't know exactly what it is, but the key of identifying it is to find what the source is. So, what we didn't touch on is that there's two major likely causes of cryptogenic strokes.

One is a blood clot from somewhere in the body, usually in the veins in the body that cross over a little hole in the heart called a patent foramen ovale, which is called a PFO. And people may have heard that term. And the blood clot crosses from the right to the left side of the heart. And then the left side of the heart goes to the brain. And that can cause a stroke, especially in young people, younger than the age of 40. The other cause is atrial fibrillation, which a lot of people have heard about.

But it's often unidentified in patients where they don't know they have it because it comes and goes. And when patients have been in atrial fibrillation, they stand the risk of forming clot in the heart, that can then go to the brain. So when we say cryptogenic strokes, it means that we have not identified it right there, but the doctors who are caring for you and the medical staff that are caring for you should look for these potential causes that may not have shown themselves when you're in the hospital. But may need long term monitoring to see if you have one of these reversible causes of stroke.

Prakash Chandran: Understandable. So, initially they're gonna look for the most common types of strokes, those kind of the reversible modalities that we spoke about earlier, but in the case that it does fall under a cryptogenic stroke, then they would kind of go towards, okay, well maybe there's a blood clot somewhere in the body that has that crossover with the heart or atrial fib relation, which is just something they have to monitor over time. Is that correct?

Dr. Neel Khanna: Sure exactly. And there are other less common causes of cryptogenic strokes, such as plaque in the aorta that may have broken off. But the point is that the obvious causes of stroke, like high blood pressure, or if someone is already in atrial fibrillation. And we know that, and we know that's the cause of the stroke. Those are easily identifiable while the patient is in the hospital. But what we want and what the movement is now for that patients who have been diagnosed with a stroke without a known cause while they're in the hospital, they should really have long term monitoring to make sure it's not one of these other causes.

So often patients are discharged with follow up with their neurologist, their brain doctor, or their heart doctor. And often I know myself as a heart doctor go have a lot of these patients who've had cryptogenic strokes, wear a heart monitor for maybe a month or maybe even more than a month so that we can see if they're having atrial fibrillation. An abnormal heart rhythm that can cause a blood clot in the heart that can go to the brain so that we can pick this up.

I think often in the past, a lot of these patients were just treated with aspirin and we hope that they don't have another event. Whereas now we're finding that there are causes of these strokes cryptogenic strokes, but that it may take a little longer for us to figure out what the cause is, and they just have to be followed so we can figure that out.

Prakash Chandran: So if I'm understanding this correctly, there's no real way. Anticipate or prevent something that falls under a cryptogenic stroke. But the important thing is if one occurs that monitoring after your discharge is key. So the doctor can work with you to see if it's atrial fibrillation or the blood clot that's potentially appearing somewhere else. Is that correct?

Dr. Neel Khanna: Exactly. And we do tests that can identify whether a patient has, like I talked about before that little hole in the heart called a patent foramen ovale, we test for that. We have heart monitors that test for whether the patient has atrial fibrillation. And the point is exactly what you said that at the time of discharge, there was no direct preventative measure that we could use, because we don't really know the source of the stroke. But in the long term, if we pick up atrial fibrillation in a patient who presented with a stroke.

And we may pick it up on a heart monitor three weeks after the stroke, when they're at home, then we potentially have found the source of their strokes and they would be started on blood thinners to help prevent this from happening in the future. So the idea is. If you follow up with your doctors, especially if you're given this diagnosis of cryptogenic stroke, if you follow up with your doctors, potentially in the weeks and months after you've had this event, we can find out what potentially caused the stroke and prevent it from happening in the future again.

Prakash Chandran: Now you hear a lot about these Apple watches being heart monitors. Is that something that patients can use to communicate with you if they're having, for example, atrial fibrillation, or is there something more official that patients need to monitor themselves with?

Dr. Neel Khanna: That's actually a really good question. And it's, I think it's an evolving question. What I would say is that Apple watches at this point and Fitbits have some of these abilities also to detect irregularity and heart rhythms. That may be atrial fibrillation, that it's an evolving technology. I can tell you personally, as a cardiologist, I have had multiple patients come to me think that their Apple watch has alerted them to atrial fibrillation and it's been accurate. And we pick it up on a monitor and they do have this atrial fibrillation that comes and goes.

And potentially that patient may have prevented a future stroke for themselves, which is huge thing. What I have seen is that often there are also false positives where they get a lot of alerts that scare them. It doesn't turn out to be something. At this point, the gold standard for monitoring people for heart rhythm, and to make sure that they don't have atrial fibrillation as the cause of their stroke, which is a big cause of cryptogenic strokes as we talked about. Is a heart monitor that a doctor gives because we can actually evaluate an active EKG on that patient and can make sure if the rhythm is normal or not.

Whereas the Apple watch may pick up irregularities and rhythm due to people with deep breathing disorders can have irregular rhythms. There are other causes of it is my point. So I think it's an evolving technology that I think in the future will have very big implications. And I often tell my patients who have this atrial fibrillation that come and go. But it's not the worst idea in the world to have an Apple watch or a Fitbit that can detect irregularity so that we can at least have a general idea. If potentially something may be going on with their heart rhythm.

Prakash Chandran: That's helpful to understand. And I guess the final question is if atrial fibrillation, for example, is detected in the monitoring phase, are there different treatment plans or protocols for these different types of cryptogenic strokes?

Dr. Neel Khanna: Yes. Any patient who has atrial fibrillation detected long term or on any monitor, especially if they've had a stroke in the past, irregardless of age need to be treated with blood thinners because atrial fibrillation promotes formation of blood clots in the top part of the heart that can be ejected and go to the brain and cause stroke. It's one of the leading causes of stroke, obviously. And one of the leading underdiagnosed causes of stroke and particularly cryogenic stroke, like we talked about.

So if you, if atrial fibrillation is picked up on a heart monitor and the patient especially has had a stroke in the past, blood thinners are key and will basically bring their risk down to as if they didn't have atrial fibrillation. So it's a big thing. And also for patients who we detect atrial fibrillation, they may be candidates for certain types of medication to help prevent it. And also procedures like ablations that can help get rid of atrial fibrillation in the long term. But the first step is detecting it.

And the take home message here is that often are patients who come in with strokes when they're in the hospital. And when they have a heart monitor on, we may not pick it up. That doesn't mean that it didn't happen and that it wasn't occurring. It just may mean that it wasn't happening in the hospital. And then often with longer term monitors when they're at home and they're eating and drinking, like they normally do is when we see that they do have these irregular rhythms, occasionally that could have caused their cryptogenic stroke.

Prakash Chandran: Well, Dr. Khanna, this has been a very fascinating and informative conversation. Is there anything else you wanna share before we sign off today?

Dr. Neel Khanna: No, basically that obviously stroke is one of the leading causes of morbidity and mortality in America. And I think the medical community neurologists primary care doctors, cardiologists are really determined to help prevent some of these strokes that can be prevented. And especially patients who present with multiple strokes, where there hasn't been a clear identified cause, that we now have tests that could long term identify the cause and prevent a future event. And that's the key follow up with your doctors after you leave the hospital and make sure that all your risk factors are being managed appropriately.

Prakash Chandran: All right, Dr. Khanna, thank you so much for your time. And I think that's the perfect place to end. That was Dr. Neel Khanna the medical director of the cardiovascular Institute at Montefiore St. Luke's Cornwall. Thanks for checking out this episode of Doc Talk. You can head to Montefioreslc.org to get connected with Dr Khanna or another provider.

If you found this podcast to be helpful, please share it on your social channels and be sure to check out the entire podcast library for topics of interest to you. My name's Prakash. Thanks again for listening. Be well.