Jeffrey Goldberger, MD, Chief of the Cardiovascular Division at the University of Miami Miller School of Medicine talks about Afib and the 4D Blood Flow MRI.
Interview conducted by Ivanhoe Broadcast News in July 2018.
First of all we hear of it as being called Afib but tell us what is Afib exactly, atrial fibrillation and is it common, are a lot of people affected?
Dr. Goldberger: I’ll answer that second part first. Atrial fibrillation is actually the most common treated arrhythmia in the United States. And prevalence numbers anywhere between six million predicted to rise to almost twenty million Americans. So it’s actually quite common. The best way to describe atrial fibrillation: everybody knows what a heart rate is and normal heart rate may range anywhere between fifty and eighty beats per minute and that’s initiated by the heart’s own pacemaker. And that then spreads in to the upper champers which are called atria and then from there in to the lower chambers. So typically if your heart rate is sixty your pacemaker is firing at sixty, your top chambers respond at sixty and then your lower chambers respond at sixty. What happens in atrial fibrillation is the electrical activation in the top chambers becomes very chaotic and rapid and could go up to four or five hundred activations per minute. Okay so that’s really, really fast. And fortunately your heart has some control mechanisms to make sure the lower chambers don’t go that fast but it has a lot of potential implications. It can cause symptoms from the erratic heart rate and it could be more rapid than normal. And then the top chambers, the atria, they can’t contract when they’re being activated that fast. So instead of pumping the blood you actually get sort of quivering of the chambers and when blood doesn’t flow through very well it can cause blood clots to form and if those travel anywhere to the body particularly the brain it could cause a stroke.
When you mentioned the symptoms, does Afib always cause symptoms or could someone have it and not even know about it?
Dr. Goldberger: We see plenty of people where atrial fibrillation is found incidentally. So they have no symptoms and then we obviously see plenty of patients who have symptoms. It could be palpitations or shortness of breath or exercise intolerance, light headedness. There’s a whole range of symptoms that can be associated with the atrial fibrillation.
And this can happen to someone really of any age, it can affect them?
Dr. Goldberger: It becomes much more common as people get older but we certainly see people even in their twenties and thirties occasionally come in with atrial fibrillation.
Does it always need to be treated?
Dr. Goldberger: That’s an excellent question. It almost always requires some sort of treatment. What’s not clear is what the right treatment is for atrial fibrillation. We do know that obviously we have to address the patient’s symptoms so if a patient has symptoms and we need to put them on medications to address that. And then the other thing that we have to address one way or another is the risk for stroke.
Mention some of the medications that a person with Afib might be put on.
Dr. Goldberger: There are probably three groups of medications that they would be put on. One are what we call rate slowing medications, so if the heart is beating too fast the lower chambers because the upper chambers are going really, really fast then we have to give medications to sort of block some of those impulses and those are called rate slowing medications. The second group of medications would be anti-arrhythmic medications. So there are medications that we can use to restore the rhythm back to normal. And then the third group of medications would be the anticoagulants either true blood thinners or aspirin on occasion.
So talk a little bit about, if it makes sense to jump to the study, what you guys are doing here at the University of Miami, what it’s called and what you’re looking at in some of these patients with Afib.
Dr. Goldberger: Our interest is in particularly trying to understand the risk for stroke in patients with atrial fibrillation. So even though we know that there’s a risk right now what we use is a clinical scoring mechanism. It has a fancy name it’s called the CHADS VASCs score and it basically looks at clinical factors like congestive heart failure, hypertension, age, diabetes, prior stroke, vascular disease and sex to try to come up with a range of scores and a range of risk for atrial fibrillation. The problem with our clinical risk score is it’s not very predictive. So we have a way to measure prediction, it’s called the C static and basically if a score is completely non-predictive it would have a score of point five or a half meaning it’s fifty, fifty. The CHADS VASCs score is about point six two. So it’s a little better than a coin toss but it’s not great. And we based on our clinical experience we said we need to come up with a better way to try to figure out who is really at risk for having these blood clots form and having a stroke. And we said the best way is to go back to the physiology and the physiology is poor flow. If there’s poor flow in the left atrium then blood clots may form. And so we decided that we have to come up with a way to measure the actual flow in the left atrium.
What is the study called and what are you looking at specifically when it comes to blood flow, why is that so important?
Dr. Goldberger: Our study that we’re doing right now, we’re using a technique called 4D flow MRI which is just a specialized analysis of typical cardiac MRI information that we get. And what it allows us to do is actually measure in every part of the atrium, the blood flow velocity or speed throughout the cardiac cycle. And one of the things that we need to understand is how much of an impact atrial fibrillation has on the blood flow. So in other words all these patients who have atrial fibrillation have some sort of disease in their atrium. And they may have contractile dysfunction so even in normal rhythm their atrium may not beat very well. We don’t know how to access whether the normal rhythm is associated with low velocity or preserve velocity. So what we’re doing is we’re taking patients who have atrial fibrillation and are going to have something called the cardioversion, that’s a shock therapy where we restore the rhythm back to normal. So we’re able to measure their blood flow velocity when they are in atrial fibrillation before the cardioversion and then we bring them back after the cardioversion when their heart rhythm is back to normal and we’re able to then access their blood flow velocity with normal rhythm. And we’re hoping to find that restoring the rhythm to normal improves the blood velocity.
This is the actual procedure they’re going through, the ones enrolled in the study?
Dr. Goldberger: Yes.
What you just said, if you do that and that does seem to help with blood flow to not put them at risk for stroke would that be the new treatment eventually or would that be the standard treatment or patients with Afib that’s severe.
Dr. Goldberger: I think your question is how this fit in to our then clinical management for these patients. So right now we are in a bit of a conundrum, so if you have a patient with atrial fibrillation and you do a cardioversion or any other treatment and you restore their rhythm to normal do they still need to be on the blood thinners or not. And for right now it’s our best guess and best guess is not good enough when it comes to having a stroke if you’re not on the blood thinners or having a major bleed if you are on the blood thinners. I don’t think it’s a good idea to rely on the best guess and we’re hoping that this kind of information will eventually, because our study is still very preliminary, but we hope that eventually it will lead us to better clinical decision making about who needs blood thinners and who doesn’t need blood thinners when we restore the rhythm back to normal.
There’s a great number of people in this country on blood thinners right?
Dr. Goldberger: That is correct.
So the thought might be they may not all need to be on them which is critical information. It’s a risk versus benefit type thing.
Dr. Goldberger: That’s correct. Sometimes I like to look at this in a backwards way and so we know that about ninety percent of people with Afib have a CHADS VASCs score, that clinical risk score anywhere between two and six okay. So if you look at that ninety percent of people if you don’t put them on blood thinners the average annual risk for a stroke is five percent, so that’s a lot. But the annual risk of not having a stroke is ninety five percent right. And if you were to just annualize that for five years probably about sixty percent will not have a stroke in five years. So now think about the fact that we’re treating the sixty percent that are not going to have a stroke in five years with blood thinners over those five years and the blood thinners have a three percent risk of major bleeding per year. That’s where we can begin to have some impact. If we can figure out who that sixty percent are and not put them on the blood thinners then we will have done an amazing thing.
That’s pretty awesome. How far are you in the study?
Dr. Goldberger: This whole technique is something that I’ve been working on for probably the last five or six years and there’s been a lot of development work. We’re starting to do some clinical studies like this to try to look at these affects. But eventually it will require some large scale trials to look at outcomes. It’s still not close to being implemented in to practice but I think that’s the excitement of the future.
What have you found, has there been findings that you could say, okay this occurred and maybe we go in this direction. The percentage that might have a stroke and of that percentage are there any leads that you have? Do you have an idea of where this might go.
Dr. Goldberger: Yeah. We’ve done a lot of basic studies trying to understand this. One of the things that we looked at is, well how does our measure of the flow in the left atrium relate to this CHADS VASCs score which is our clinical risk score. And the good news is it relates and the even better news is that the relationship is not very strong which means that if the CHADS VASCs is not very good that perhaps this might be better. Perhaps, and that’s what we still need to prove. But if there was just a very strong correlation between our measure and the CHADS VASCs score then it will be no chance that it could be better. So we have learned that we’ve done some correlative studies looking at different parts of the left atrium and where we might actually see difference in flow velocities and the one thing that we do know about the blood clots that form in the left atrium is they tend to form in a part of the left atrium called the left atrial appendage which is a pocket which comes out of the left atrium. And we have seen some reductions of flow velocity in that area. So it correlates with what we know happens in terms of blood clots.
How many patients are enrolled in the study and are you looking to enroll any more at this point?
Dr. Goldberger: We are looking to continue enrollment and we probably have about a dozen patients enrolled.
Any specific candidate you’re looking for or can it be anyone who does suffer from Afib?
Dr. Goldberger: The patients for this particular study are patients who have atrial fibrillation and are having a planned or elective cardioversion so shock treatment.
If they have that planned?
Dr. Goldberger: Yeah, so we have to be able to do the MRI before and one after.
Anything that you can mention regarding the patient we’re going to meet today?
Dr. Goldberger: He participated in the study and again we’re just collecting the data; it doesn’t impact any kinds of treatments today. Like I said we are hopeful that in the future it may be useful for clinical decision making but as of today it’s just really collecting the information.
Why such a rise in Afib that even though you are predicting, why this rise? What do you think is causing that?
Dr. Goldberger: There are many factors that probably play in to that. Certainly age and population. And it is a disease that is more common as people get older. There are a lot of clinical risk factors for atrial fibrillation including obesity and sleep apnea, hypertension, diabetes and these are all things that are increasing in prevalence, so I think all these things play in to the increased prevalence of Afib.
And that’s why it’s so critical to do this study.
Dr. Goldberger: Yeah. All the predictions are for dramatic rises in the future for Afib.
So is there anything else you want to mention?
Dr. Goldberger: No I think we’ve got it.
END OF INTERVIEW
This information is intended for additional research purposes only. It is not to be used as a prescription or advice from Ivanhoe Broadcast News, Inc. or any medical professional interviewed. Ivanhoe Broadcast News, Inc. assumes no responsibility for the depth or accuracy of physician statements. Procedures or medicines apply to different people and medical factors; always consult your physician on medical matters.
If you would like more information, please contact:
Kai Hill, PR, University of Miami Miller School of Medicine
305-243-3249
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