What Causes Heart Palpitations at Night?
Could Untreated AFib Raise The Risk Of Memory Decline?
A large study found that there is an association between untreated atrial fibrillation and eventual mild cognitive impairment (MCI) that may lead to dementia.
Researchers found that people with atrial fibrillation (AFib) were at a 45% higher risk of MCI than those without AFib, or with AFib that was being treated.
The study analyzed electronic health records from January 1, 1998 to May 31, 2016 for 4,309,245 individuals residing in the U.K. Each of the 233,833 people with AFib was matched with one of 233,747 people of the same sex and age, but without AFib, to serve as a control. The mean age of individuals was 74.2.
The researchers adjusted for a wide range of potential MCI risk factors, including sex, age, socioeconomic status, hypertension, smoking, diabetes, obesity, high cholesterol, atherosclerotic heart disease, peripheral artery disease, heart failure, stroke, cancer, hearing loss, thyroid disease, depression, chronic kidney and liver disease, and chronic obstructive pulmonary disease.
The researchers found that people being treated with two drugs, digoxin or amiodarone, along with oral anticoagulants — blood thinners — were not at a higher risk of MCI than controls.
The study is published as a research letter in JACC: Advances.
Atrial fibrillation is a form of arrhythmia characterized by an irregular or quivering heartbeat. It can lead to several cardiovascular complications, including stroke, blood clots, and heart failure.
AFib currently affects more than two million U.S. Adults, and the American Heart Association predicts that 12 million people will have AFib by 2030 as the national population ages.
AFib is caused by an irregular beating in the atria, the upper chambers, of the heart. When this occurs, some of the blood that should be pumped out from the heart remains. This pooled blood can form clots in the heart that may eventually be pumped out to the brain, causing a stroke.
"The thought has been that if someone has atrial fibrillation — especially under-treated atrial fibrillation — they're having multiple little embolic strokes," cardiologist Dr. Paul Drury, associate medical director of electrophysiology at MemorialCare Saddleback Medical Center in California, who was not involved in the study, explained.
"Silent brain infarcts, like silent heart attacks do damage to tissue and cells, regardless of symptomatology, or lack thereof. AFib, in particular, is recognized as a risk factor for silent brain insults in this population," said Dr. Jayne Morgan, cardiologist and clinical director of the Covid Task Force at the Piedmont Healthcare Corporation in Atlanta, GA, who was also not involved in the study.
"Over time, this takes its toll on cognitive function, accelerating mental decline. This is because small blood clots, which are more common to develop with untreated AFib, can block small arteries feeding oxygen to the brain, depriving the brain of oxygen and then [causing] the subsequent death of that tissue," she said.
"Those strokes eventually will affect the volume of brain tissue and healthy brain tissue and then lead to cognitive impairment, and then dementia," noted Dr. Drury.
In addition to the association with AFib, the researchers found that older people, women, those experiencing higher socioeconomic deprivation, or a clinical history of depression, stroke, as well as a combination of such factors, were somewhat more likely to develop MCI.
The researchers also found that people with AFib who developed MCI were at a higher risk of developing dementia.
The risk factors most likely to result in dementia were smoking, sex, chronic kidney disease, asthma, and multicomorbidity, or having multiple risk factors.
In the research letter, Dr. Morgan said "It was astonishing to see that all 20 co-morbidity variables were not only often higher in the AFib group, but those that were higher were often more than twice as high as the controls."
She also pointed out one especially striking, often overlooked co-morbidity—hearing loss, which has been linked to an increase in cognitive decline.
The medications mentioned in the study, digoxin and amiodarone, were in use more widely during the earlier years of the study than they are today.
Dr. Drury said digoxin "is not actually recommended for treatment of atrial fibrillation anymore — it is one that only controls the heart rate." While amiodarone, an antiarrhythmic medication, is still in use, Dr. Drury said it is not as frequently prescribed now due to "a lot of side effects."
Instead, he said, "there is cardiac ablation, which is now one of our first-line therapies that didn't start really until the early 2000s." He noted that there are other antiarrhythmics, but they are not as commonly used as amiodarone once was.
Dr. Drury explained cardiac ablation:
"We go minimally invasively from the veins in the legs all the way up to the heart, and we ablate, or cauterize, the tissue in the heart that causes atrial fibrillation. So instead of putting a band-aid on it with medication, we're actually fixing the problem."
Since cardiac ablation is only about 70–80% effective, it is frequently supplemented with anticoagulants.
"Treatment of AFib is not just a cardiac consideration, but a cognitive one as well. [The] takeaway is that it is critically important to manage all co-morbidities to goal in AFib patients, as not doing so could both hasten and increase the risk of mental disability in these patients as they age."— Dr. Jayne Morgan
This Maker Of An Atrial Fibrillation Device Has Nearly 70% Upside, JMP Securities Says
Investors should scoop up shares of medical device provider AtriCure , according to JMP Securities, which expects the company to be a winner in one burgeoning medical device market. Analyst Daniel Stauder initiated coverage of the stock with an outperform rating and $60 price target, implying shares could soar almost 70%. "Representing the number one player in treating complex forms of atrial fibrillation, the company has carved out a dominant position in two major legacy cardiac arenas that are still growing at a very healthy clip, and where it is primarily the only game in town," Stauder wrote in a Monday note. "The company's efforts to drive operating leverage and achieve positive adjusted EBITDA should, in our view, bode well in the current MedTech landscape." AtriCure develops, manufactures and sells devices that are used for the treatment of atrial fibrillation, or Afib; left atrial appendage management, or LAAM; and post-operative pain. The devices are marketed to medical centers. The company's stock price has declined just about 19% so far this year, with almost all of that occurring this quarter. Shares briefly climbed 4.8% in early trading Monday before pulling back. ATRC YTD mountain AtriCure stock. According to Stauder, AtriCure has moved into two emerging opportunities that represent even larger total addressable markets than the company's traditional niche, and JMP views both as offering additional opportunity. These include the company's Open Ablation products, which are the only FDA-approved technologies for the treatment of persistent Afib, and its AtriClip product, which is the most widely used LAAM device and has demonstrated benefits in preventing increased risks of blood clots and stroke, the analyst said. Both segments generate about 35% and 40% of total sales, respectively, and are expected to generate mid-teen annual sales growth in 2024 and 2025. The company's fast-growing post-operative pain management division is another growth opportunity, according to Stauder. The analyst said that this segment, with a possible total addressable market approaching $1 billion, is likely to expand roughly 20% year over year in 2023, 2024 and 2025. It has already grown to account for 12% of revenue today, up from 5% in 2020. AtriCure's pain management division "adds an attractive layer of growth that should outpace ATRC's legacy product portfolios," Stauder said. — CNBC's Michael Bloom contributed to this report.
How A Heart Procedure For Atrial Fibrillation Can Prevent A Stroke, And Dementia
Norman Swan: Hello and welcome to this week's Health Report with me, Norman Swan, on Gadigal land.
Tegan Taylor: And me, Tegan Taylor, on Jagera and Turrbal land.
Today, a little visit to Australia's home of poo transplants.
Norman Swan: Delicious!
News about what might be happening in your general practice.
And two of the most common causes of death globally and in Australia, and they're related, and they're stroke and dementia. And how a heart procedure may help to prevent dementia.
Tegan Taylor: Well, let's talk about that. Because on stroke, there's been a really big chunk of new knowledge that's come out recently; Lancet Neurology has a commission on stroke, which brings together the latest research and statistics, that kind of thing. Can you take me through what the main points of that were?
Norman Swan: Well, stroke (we're talking here about clots in the arteries in the neck that spin off to the brain), that's the commonest one in Australia, and haemorrhage in the brain which is more common in countries like Japan. But globally, clot-based strokes are the commonest cause, and high blood pressure, smoking, obesity, diabetes, those are the kinds of risk factors for stroke, as well as age. And it's the second commonest cause of death in the world, and also a major cause of disability. And what this commission has shown is that over the next 20 or 30 years the numbers of deaths will double internationally.
Tegan Taylor: That is so terrifying to me, and kind of feels counterintuitive when you know that we're making so many medical progressions, that science has given us so much.
Norman Swan: That's in a lucky country like Australia, but if you're living in a low to middle income country, you don't necessarily have a good network of general practice, they're not necessarily controlling blood pressure well, controlling smoking, and they've not necessarily got high quality healthcare interventions to treat stroke when it occurs and actually rehabilitate. And the really worrying thing that they're finding is that it's increasing in people under 55.
Tegan Taylor: Why?
Norman Swan: Probably obesity and diabetes, although it's not quite known. Now, in Australia we've been a world leader in stroke reduction, deaths from stroke in Australia have been declining at 2% or 3% a year for probably more than 30 years, which is dramatic, but pre-Covid that was beginning to tail off, and we actually covered that a little bit on the Health Report. And then post-2020 there's been an uptick in deaths from stroke, some of which will be Covid and some of which may well have happened anyway and reflects what's happening internationally.
But one of the causes of stroke is atrial fibrillation. And there are a lot of people in Australia with atrial fibrillation. This is an abnormal heart rhythm, which can cause stroke because blood pools in these atria at the top of the heart and spins off and causes stroke, and it also may well cause dementia. So you get lightheaded, you get palpitations, you can faint, a hyperactive thyroid is another cause of atrial fibrillation, and is a real problem.
Tegan Taylor: Yeah, on a previous Health Report I spoke to a Brisbane man called Paul about what it's like to have atrial fibrillation, just in case you have any doubt about how awful it can be because here's what he said:
Paul: It feels like a horse kicking in your chest and in the back of your throat, it makes you sweat, it makes you feel uneasy, quite a bit anxious sometimes, tiredness of course, breathlessness.
Norman Swan: That was Paul. Now, Professor Jonathan Kalman is an authority on atrial fibrillation and its treatment. He's at the Royal Melbourne Hospital.
Jonathan Kalman: In Australia, the numbers would be considered around 500,000 people will be affected by atrial fibrillation. We know that it is a condition that increases with advancing age, and so beyond 60, 70, 80 somewhere between 5% and 10% of the population may well be affected by atrial fibrillation. And it occurs at a time in life when people are often still extremely active, working, and it can really impact their quality of life at the time that they develop this.
Norman Swan: There are two ways of treating atrial fibrillation. One is using drugs to control the speed of the heart and the rhythm, trying to make it more regular. The other is what's called catheter ablation, and Jonathan Kalman is one of the pioneers of the procedure in Australia.
Jonathan Kalman: Ablation for atrial fibrillation now has been around probably for close to two-and-a-half decades but has been evolving and improving over that period of time, and it's now a very mature and advanced procedure. It's a procedure where we go in through the veins, usually accessed or almost invariably accessed through the vein in the groin, and we go up into the heart and we cross the membrane in the middle of the heart from the right side to the left side. And we either cauterise or freeze the areas responsible for initiating atrial fibrillation so that they can no longer stimulate or initiate that heart rhythm disturbance where the heart's beating rapidly and erratically and inefficiently.
Norman Swan: So you're trying to basically get rid of the electrical wiring that's gone wrong.
Jonathan Kalman: Exactly that. Surprisingly, the usual location for that abnormal electrical wiring is sleeves of muscle that are inside the veins coming from the lungs to the heart, the so-called pulmonary veins, and that was an observation made approximately two-and-a-half decades ago.
Norman Swan: So what are the success rates? I mean, in the old days when I first covered this, cardiologists were having to go in three, four times to finish off the job. What is it now?
Jonathan Kalman: So the success rate has certainly improved markedly over time and that's with the evolution of technology, which is really markedly better than it has been in the past. The success rate is determined by two major parameters. One is patient related factors. So what type of atrial fibrillation is this? Is it the paroxysmal form, or is it the continuous or persistent form? And are there other structural problems with the heart? So, more advanced structural abnormalities of the heart will be associated with lower success rates. And the other is a conversation we're having a lot these days, is how we define success. And for many years we've defined a failed ablation as one associated with 30-second recurrence, and we now know that 30 seconds really is a meaningless number in terms of symptoms and in terms of the risks associated with atrial fibrillation.
Norman Swan: So just to clarify, this is when you're having a monitor on you, and you have a short burst of atrial fibrillation that lasts 30 seconds.
Jonathan Kalman: Exactly, that's exactly right. And most patients are completely unaware of that. And we're moving to an understanding where probably AF that lasts more than an hour, to pick a rough figure, is associated with patients' symptoms and also potentially with risks. So when we think about those factors, I think we can comfortably say to people that the success rate for this procedure varies somewhere between 70% and 80%, and that the likelihood of needing a second procedure is probably in the 15% to 20% range. And again, it really does depend on what type of AF you have.
Norman Swan: And on complications and side effects, one of the feared side effects, complications, in the early days, particularly when you were doing repeated burning of the veins, is that you would get a scarring problem of the left atrium. So, to explain to the audience, you've got four chambers in the heart, you got the upper chambers, the atria, the lower chambers, the ventricles, and the blood comes into the atria to fill up the ventricles, and that you would get shrinkage of the left atrium, and that's an untreatable condition. In fact, heart transplantation is the only treatment for it. To what extent is that a problem with ablation, or was that a theoretical issue?
Jonathan Kalman: It's an incredibly rare complication. It's one I must say in over 4,500 ablations in our institution that we have never seen. And I think it's very specifically related to very extensive ablation and that's not really performed in any labs that I'm aware of in Australia. There had been a few labs around the world suggesting that you need this form of extensive ablation in order to have higher cure rates in patients with more advanced forms of atrial fibrillation. We've never gone down that path and it certainly is an exceedingly rare complication.
Norman Swan: Jonathan Kalman.
Apart from stroke, one of the consistent associations with atrial fibrillation is an increased risk of dementia. A recent very large study comparing drug treatment of atrial fibrillation with catheter ablation has found that ablation reduces the dementia risk. One of the researchers was Dr Stephanie Harrison of the South Australian Health and Medical Research Institute in Adelaide.
Stephanie Harrison: It's been quite well established that having atrial fibrillation can increase a person's risk of dementia. There's been many different research studies suggesting this. When a person has atrial fibrillation, it can increase the risk of stroke, so people with atrial fibrillation have a fivefold increased risk of stroke. But also because of the impact on blood flow in the heart of atrial fibrillation, the potential increased risk of clotting and other mechanisms, it may also increase a person's risk of dementia.
Norman Swan: So this is not a randomised trial here. You've observed people who've got atrial fibrillation and their treatment and then followed them through, I think nearly 21,000 people in fact, in their late 60s, who had or had not got catheter ablation for their atrial fibrillation. What did you find over what period of time?
Stephanie Harrison: We followed actually over 20,000 people who had catheter ablation, we matched them with the same amount of people who did not have catheter ablation, so they just had medicines instead. We followed them for at least to five years retrospectively, so that means we looked back in time. We found that the people who had catheter ablation had a lower risk of dementia compared to those who did not. And we use different statistical approaches to try and account for the differences between people, apart from whether they had catheter ablation or not, so we accounted for differences in their age or their health conditions. But this is a very large study, and it agrees with the findings of other observational studies which have found similar results; people having catheter ablation having a lower risk of dementia.
Norman Swan: And is it all dementia, or is it just vascular dementia?
Stephanie Harrison: So in this study, we looked at all types of dementia. When we looked via the different types, we found it for both Alzheimer's and vascular dementia. The main outcome, we just looked at all types of dementia.
Norman Swan: It was like a 48% reduction, which is not insignificant.
Stephanie Harrison: So this is the relative reduction, but relatively there was a 48%...
Norman Swan: I mean, it's fine to say you've had ablation, but the ablation might not have worked. Were you able to correlate with success?
Stephanie Harrison: Unfortunately in this study we weren't able to look at whether the ablation was successful or not, so that's an important consideration.
Norman Swan: The bottom line?
Stephanie Harrison: Importantly, atrial fibrillation isn't always detected. So to consider any of these different treatments, firstly we need to detect it. And with emerging smart technologies and new technologies for detecting atrial fibrillation, hopefully in the future we will see more opportunities for people to detect atrial fibrillation earlier so the appropriate treatment can be initiated.
Norman Swan: Yeah, there's devices for iPhones and wearables that may well be quite accurate in detecting atrial fibrillation. That was Dr Stephanie Harrison.
Jonathan Kalman has recently done a trial comparing ablation with drug therapy for atrial fibrillation, looking at psychological distress.
Jonathan Kalman: It's an observation I made just in the office when I was sitting with couples and they were talking to me about, let's say, the husband's atrial fibrillation, and the wife would say, 'Look, he's just not the same person anymore. He's withdrawn and irritable and morose, and frankly depressed.' And I'd heard that so many times over the years that I thought this is important and something we need to quantify and evaluate and see how we're doing, because traditionally cardiologists have asked questions about palpitations and breathlessness and exercise tolerance and dizziness, but we haven't thought about the psychological and emotional impact of the symptoms on our patients, to an extent.
Norman Swan: And is the cause that you're worried about when the next attack of atrial fibrillation is going to come on and what it's going to do to you, is that what's underlying this?
Jonathan Kalman: That's a big part of it, it's the uncertainty of another episode. It's the curtailment of lifestyle, people stop exercising, stop doing the things that they love, because they're worried that it'll trigger an episode, or they don't want to travel because they're worried that they'll get an episode when they're far from home or far from help. And so they start to constrict and reduce their lifestyle, and that has the secondary impact. And if it's continuous AF and that impact is ongoing, you know, they can't exercise in the way they used to, you know, they feel unwell much of the time, the drug's side-effects, so all of those things add up to a significant impact on people's psychological wellbeing.
Norman Swan: Now, ablation isn't the only therapy for atrial fibrillation, you can have drugs which affect the heart rate, to slow the heart rate down, which is where you get the exercise tolerance problem, and ones that control the rhythm. And what you did was a randomised trial of ablation versus medical therapy where the outcome you were looking at was psychological distress. What did you find?
Jonathan Kalman: Patients who underwent ablation over 12 months of follow-up had significant reductions in their AF burden, in their physical wellbeing, and that with that really very dramatic improvements in their mental health that weren't seen in the medical arm, and that that improvement in those markers of anxiety and depression was sort of gradual in that at three months it was trending to a significant difference, by six months it was clearly very different, and by 12 months that difference had increased again. So that what we were seeing is that over that period of time, as patients got their confidence back, that they could return to physical activity and return to doing the things they love, and that they did do that and they were now off their medications and doing well, and that sense of psychological and emotional wellbeing improved progressively.
Norman Swan: Can the country afford ablation to be the primary therapy and are there enough trained cardiologists to do it?
Jonathan Kalman: There are quite a number of studies now showing the overall economic benefit of catheter ablation in that patients aren't coming back to doctors repeatedly for change of medication, they aren't presenting to emergency departments for cardioversion, the electrical zaps that we give them when they're in AF to get them back to normal. And we are seeing reductions in many studies in the complications of atrial fibrillation, the risks of stroke and of heart failure, and then the other impacts such as premature mortality. The technology is expensive, but the costs of the technology are dropping progressively. And when you look at the big picture, is indeed cost effective.
In terms of the number of physicians, there's certainly been a significant increase in the number of physicians performing this procedure. There are new technologies coming all the time. And so we do have a lot of people in the training pipeline, and I think that we will be able to offer this procedure very widely and very rapidly. But we must continue to think about which patients are those who are most appropriate to receive the procedure.
Norman Swan: Jonathan Kalman, thank you for joining us on the Health Report.
Jonathan Kalman: Thanks so much, Norman, great to be here.
Norman Swan: Jonathan Kalman, who is Professor of Medicine at the University of Melbourne.
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