Tag: atrial fibrillation

Even Moderate Amounts of Exercise May Reduce Risk for Atrial Fibrillation

Photo by Robert Ruggiero on Unsplash

Adding an extra hour every week of physical activity may lower the chance of developing the most common type of irregular heartbeat (arryhthmia) by 11%, a new study shows.

Led by researchers at NYU Langone Health, the investigation focused on atrial fibrillation. While past studies have linked exercise to reduced risk of this type of arrhythmia, nearly all of these analyses have relied on participants’ often inaccurate estimates of their own activity levels, the authors say.

To avert this flaw, the current study team used data recorded from the fitness tracker Fitbit to objectively measure physical activity in more than 6000 men and women across the United States. The results showed that those with higher amounts of weekly physical activity were less likely to develop atrial fibrillation. Notably, the researchers say, even modest amounts of moderate to vigorous exercise, which can range from taking a brisk walk or cleaning the house to swimming laps or jogging, were associated with reduced risk.

Specifically, study participants who averaged between 2.5 and 5 hours per week, the minimum amount recommended by the American Heart Association, showed a 60% lower risk of developing atrial fibrillation. Those who averaged greater than 5 hours had a slightly greater (65%) reduction.

“Our findings make clear that you do not need to start running marathons to help prevent atrial fibrillation and other forms of heart disease,” said preventive cardiologist Sean P. Heffron, MD, the study senior author. “Just keeping moderately active can, over time, add up to major benefits for maintaining a healthy heart,” added Dr Heffron, an assistant professor in the Department of Medicine at NYU Grossman School of Medicine.

Dr. Heffron notes that in the sole earlier study that used activity monitors to investigate atrial fibrillation, researchers provided Fitbit-style monitors to the participants and tracked them for only a week, an approach that may not have accurately captured their normal workout habits. The new investigation, which the authors say is the largest of its kind to date, assessed participants for a full year and included only those who already owned the devices.

A report on the findings will be presented at the annual meeting of the American Heart Association on November 16.

From data collected as part of the All of Us Research Program, the authors of the current study assessed physical activity in the subset (6086 people) who used a Fitbit device and permitted their Fitbit and electronic health records to be linked to their All of Us data. The team tracked activity information for a year as a baseline and then followed up for another five years to identify those who were diagnosed with atrial fibrillation. The researchers also took into account factors known to contribute to the condition, such as age, sex, and a history of high blood pressure.

“These results highlight the value of Fitbits and similar monitors in medical research,” said study lead author Souptik Barua, PhD, an assistant professor in the Department of Medicine at NYU Grossman School of Medicine. “By offering an objective way to measure exercise for years at a time, these tools can provide deeper insight into how different patterns of activity can impact health.”

For example, says Dr Barua, the research team next plans to explore whether working out in the morning or at night may have different effects on heart health.

He cautions that since many Fitbit owners in the study were college-educated White women, the investigation assessed a less-diverse group than that of the overall All of Us population. The program is now providing free devices to participants in underrepresented communities for future investigations.

Dr. Barua also cautions that the study was not designed to tell whether exercise alone directly reduced the risk of atrial fibrillation, nor to detect how that might come about or what other factors, such as income or educational status, might be in play in the reduced risk. However, the association between exercise “doses” and the development of the condition in the study participants was strong.

Source: NYU Langone Health / NYU Grossman School of Medicine

Defibrillation Using 1/1000th the Energy could be Possible

Photo by Mikhail Nilov

Researchers from Sergio Arboleda University in Colombia and the Georgia Institute of Technology in the US used an electrophysiological computer model of the heart’s electrical circuits to examine the effect of the applied voltage field in multiple fibrillation-defibrillation scenarios. Their research, published in the interdisciplinary journal Chaos, discovered that far less energy is needed than is currently used in state-of-the-art defibrillation techniques.

“The results were not at all what we expected. We learned the mechanism for ultra-low-energy defibrillation is not related to synchronisation of the excitation waves like we thought, but is instead related to whether the waves manage to propagate across regions of the tissue which have not had the time to fully recover from a previous excitation,” author Roman Grigoriev said. “Our focus was on finding the optimal variation in time of the applied electric field over an extended time interval. Since the length of the time interval is not known a priori, it was incremented until a defibrillating protocol was found.”

The authors applied an adjoint optimization method, which aims to achieve a desired result, defibrillation in this case, by solving the electrophysiologic model for a given voltage input and looping backward through time to determine the correction to the voltage profile that will successfully defibrillate irregular heart activity while reducing the energy the most.

Energy reduction in defibrillation devices is an active area of research. While defibrillators are often successful at ending dangerous arrhythmias in patients, they are painful and cause damage to the cardiac tissue.

“Existing low-energy defibrillation protocols yield only a moderate reduction in tissue damage and pain,” Grigoriev said. “Our study shows these can be completely eliminated. Conventional protocols require substantial power for implantable defibrillators-cardioverters (ICDs), and replacement surgeries carry substantial health risks.”

In a normal rhythm, electrochemical waves triggered by pacemaker cells at the top of the atria propagate through the heart, causing synchronised contractions. During arrhythmias, such as fibrillation, the excitation waves start to quickly rotate instead of propagating through and leaving the tissue, as in normal rhythm.

“Under some conditions, an excitation wave may or may not be able to propagate through the tissue. This is called the ‘vulnerable window,’” Grigoriev said. “The outcome depends on very small changes in the timing of the excitation wave or very small external perturbations.

“The mechanism of ultra-low-energy defibrillation we uncovered exploits this sensitivity. Varying the electrical field profile over a relatively long time interval allows blocking the propagation of the rotating excitation waves through the ‘sensitive’ regions of tissue, successfully terminating the irregular electric activity in the heart.”

Source: American Institute of Physics

The Prevalence of Atrial Fibrillation has been Greatly Underestimated

Human heart. Credit: Scientific Animations CC4.0

Atrial fibrillation, a rapid, irregular heartbeat that can lead to stroke or sudden death, is three times more common than previously thought, affecting nearly 5% of the population, according to new estimates from UC San Francisco.

A-Fib, as the condition is commonly known, has been on the rise for at least the past decade, driven by the aging of the population, along with increasing rates of hypertension, diabetes and obesity. Earlier projections had estimated that 3.3 million U.S. adults had atrial fibrillation, but these have not been updated in more than two decades.

“Atrial fibrillation doubles the risk of mortality, is one of the most common causes of stroke, increases risks of heart failure, myocardial infarction, chronic kidney disease and dementia, and results in lower quality of life,” said first author Jean Jacques Noubiap, MD, PhD, a postdoctoral scholar at UCSF with a specialty in global cardiovascular health.

“Fortunately, atrial fibrillation is preventable, and early detection and appropriate treatment can substantially reduce its adverse outcomes,” he said.

Rising numbers reflect need for better prevention and treatment

UCSF investigators reviewed the medical records of nearly 30 million adult patients who received some form of acute or procedural care in California from 2005 to 2019. About 2 million of these people had been diagnosed with A-Fib, and the numbers grew over time, rising from 4.49% of the patients treated between 2005 and 2009 to 6.82% of the patients treated between 2015 and 2019.

The data were standardised to reflect the entire country, and researchers estimated the current national prevalence to be at least 10.55 million. They also found that during the study timeframe, A-Fib patients skewed younger, were less likely to be female and more likely to have hypertension and diabetes.

A-Fib has a broad spectrum of complications from shortness of breath and light-headedness to blood clots, stroke and even heart failure. Studies have shown that people with A-Fib are up to five times more likely to have a stroke. The authors said that by outlining the scope of the problem, these new estimates can help guide health care planning, resource allocation and public health interventions.

“Physicians recognise that atrial fibrillation is often encountered in essentially every field of practice,” said senior and corresponding author Gregory M. Marcus, MD, MAS, a cardiologist and electrophysiologist at UCSF Health. “These data provide objective evidence to demonstrate that prior projections severely underestimated how common it truly is.”

Digital technologies may reveal it is even more common than the current analysis indicates.

“With the growing use of consumer wearables designed to detect atrial fibrillation combined with safer and more effective means to treat it, this current prevalence of atrial fibrillation in health care settings may soon be dwarfed by future health care utilisation that will occur due to the disease,” Marcus said.

Source: University of California San Francisco

Sweetened Drinks Linked to Higher Atrial Fibrillation Risk

Photo by Breakingpic on Pexels

An analysis of UK Biokank data showed that adults who reported drinking two litres or more of sugar- or artificially sweetened drinks per week had a higher risk of atrial fibrillation compared with adults who drank fewer such beverages, according to new research published in Circulation: Arrhythmia and Electrophysiology, a peer-reviewed journal of the American Heart Association.

The study also found that drinking one litre or less per week of pure, unsweetened juice, such as orange or vegetable juice, was associated with a lower risk of atrial fibrillation (AFib). However, the study could not confirm whether the sweetened drinks caused AFib, yet the association remained after accounting for a person’s genetic susceptibility to the condition.

Consuming sweetened drinks has been linked to Type 2 diabetes and obesity in previous research. This large study of health data in the UK Biobank is among the first to assess a possible link between sugar- or artificially sweetened beverages and AFib.

“Our study’s findings cannot definitively conclude that one beverage poses more health risk than another due to the complexity of our diets and because some people may drink more than one type of beverage,” said lead study author Ningjian Wang, MD, PhD, a researcher at the Shanghai Ninth People’s Hospital and Shanghai Jiao Tong University School of Medicine in Shanghai, China. “However, based on these findings, we recommend that people reduce or even avoid artificially sweetened and sugar-sweetened beverages whenever possible. Do not take it for granted that drinking low-sugar and low-calorie artificially sweetened beverages is healthy, it may pose potential health risks.”

The researchers reviewed data from dietary questionnaires and genetic data for more than 200 000 adults free of AFib at the time they enrolled in the UK Biobank, between 2006 and 2010. During the nearly 10-year follow-up period, there were 9362 cases of AFib among the study participants.

The analysis found:Compared to people who did not consume any sweetened drinks, there was a 20% increased risk of atrial fibrillation among people who said they drank more than 2 litres per week of artificially sweetened beverages; and a 10% increased risk among participants who reported drinking 2 litres per week or more of sugar-sweetened beverages.

People reporting 1 litre or less of pure fruit juice each week had an 8% lower risk of atrial fibrillation.

Participants who consumed more artificially sweetened beverages were more likely to be female, younger, have a higher body mass index and a higher prevalence of Type 2 diabetes.

Participants who consumed more sugar-sweetened beverages were more likely to be male, younger, have a higher body mass index, a higher prevalence of heart disease and lower socioeconomic status.

Those who drank sugar-sweetened beverages and pure juice were more likely to have a higher intake of total sugar than those who drank artificially sweetened drinks.

Smoking may have also affected risk, with smokers who drank more than two litres per week of sugar-sweetened beverages having a 31% higher risk of AFib, whereas no significant increase risk was noted for former smokers or people who never smoked.

“These novel findings on the relationships among atrial fibrillation risk and sugar- and artificially sweetened beverages and pure juice may prompt the development of new prevention strategies by considering decreasing sweetened drinks to help improve heart health,” Wang said.

Researchers also evaluated whether a genetic susceptibility to AFib was a factor in the association with sweetened beverages. The analysis found the AFib risk was high with the consumption of more than 2 litres of artificially sweetened drinks per week regardless of genetic susceptibility.

Source: American Heart Association

Anabolic Steroid Use can Increase Atrial Fibrillation Risk, Study Finds

Photo by Jonathan Borba on Unsplash

People using anabolic steroids could be increasing their underlying risk of atrial fibrillation, according to new research published in the Journal of Physiology

The team found that male sex hormones, such as testosterone, also called androgenic anabolic steroids (AAS), which are misused for muscle building particularly among in young men can increase the risk of atrial fibrillation in individuals genetically predisposed to heart diseases.

Dr Laura Sommerfeld, Postdoctoral Researcher at the UKE Hamburg, who completed her PhD at the Institute of Cardiovascular Sciences at the University of Birmingham focusing on this work is lead author of the study.

Dr Sommerfeld said: “Our study can significantly contribute to understanding the impact on the heart health of young men who misuse anabolic steroids to increase muscle mass. Recent reports have shown that young men in particular are being targeted on social media such as TikTok being sold testosterone products, but we have shown how the misuse of steroids carries a specific risk that many people will not be aware of.”

Professor Larissa Fabritz, Chair of Inherited Cardiac Conditions at UKE Hamburg and Honorary Chair in the Institute of Cardiovascular Sciences at the University of Birmingham added:

“Heart muscle diseases like ARVC affect young, athletic individuals and can lead to life-threatening heart rhythm disturbances. Atrial fibrillation is a common condition in the general population. Elevated testosterone levels can result in an earlier onset of these diseases.”

The scientists examined potential effects on a condition called arrhythmogenic right ventricular cardiomyopathy (ARVC), which is genetically determined and primarily attributed to disruptions in the formation of cell connections critical for heart muscle stability.

The scientists initially confirmed, based on clinical patient data from UHB and elsewhere, that ARVC occurs more frequently and severely in men than in women.

In laboratory experiments, they discovered that six weeks of AAS intake, combined with impaired cell connections, could lead to reduced sodium channel function in heart tissue and a slowing of signal conduction within the atria.

Dr Andrew Holmes, co-author and Assistant Professor in the Institute of Clinical Sciences at the University of Birmingham said:

“This work implies that young male individuals with key inherited genetic changes have a greater risk of developing electrical problems in the heart in response to anabolic steroid abuse.”

The research was conducted by an interdisciplinary consortium of clinicians and researchers led by University of Birmingham and collaborators in Germany.

Source: University of Birmingham

Clinical Researchers Discover Four New Factors that Predict Atrial Fibrillation

UK researchers have developed a new way of identifying patients at risk of atrial fibrillation (AF). While not life threatening, the condition increases people’s risk of having a transient ischaemic attack (TIA) or stroke by up to five times. A new study, published in the European Journal of Preventive Cardiology, reveals four specific factors that can predict which patients will have atrial fibrillation.

The researchers investigated clinical and echocardiographic parameters for AF and found that the combination of advanced age, increased DBP, increasing lateral PA (time interval from the beginning of the P wave on the surface electrocardiogram to the beginning of the A′ wave on pulsed wave tissue Doppler of the lateral mitral annulus), and impaired LA reservoir strain is associated with AF. Other studies have linked most of these factors have been linked with an increased risk of AF in stroke survivors.

The team went on to create an easy tool for doctors to use in practice to identify those at high risk, which they hope will help diagnose and treat more patients, reducing their risk of future strokes.

Lead researcher Prof Vassilios Vassiliou, from UEA’s Norwich Medical School and Honorary Consultant Cardiologist at the Norfolk and Norwich University Hospital, said: “Identifying who is at high risk and more likely to develop atrial fibrillation is very important.

“This is because it requires specific treatment with anticoagulants, commonly known as blood thinners, to reduce the risk of future strokes.

“Patients who have had a stroke usually undergo multiple investigations to determine the cause of the stroke, as this can influence the treatment they receive long-term.

“These investigations include prolonged monitoring of the heart rhythm with a small implantable device called a loop recorder, and an ultrasound of the heart, called an echocardiogram.”

The research team collected data from 323 patients across the East of England, treated at Cambridge University Hospitals NHS Foundation Trust, who had had a stroke with no cause identified- known as Embolic Stroke of Undetermined Source.

They analysed medical records as well as data from prolonged heart rhythm monitoring. They also studied their echocardiograms.

Prof Vassiliou said: “We determined how many of these patients were found to have atrial fibrillation up to three years following their stroke, and went on to perform a thorough assessment to identify if there are specific parameters that are connected with atrial fibrillation identification.

“We identified four parameters that were linked with the development of atrial fibrillation, which were consistently present in patients that had this arrhythmia. We then developed a model that can be used to predict who will show atrial fibrillation in the next three years, and is therefore at increased risk of another stroke in the future.”

“This is a very easy tool that any doctor can use in clinical practice,” he added.

“And it can potentially help doctors provide more targeted and effective treatment to these patients, ultimately aiming to highlight the people at higher risk of this arrhythmia that can benefit from prolonged heart rhythm monitoring and earlier anticoagulation to prevent a future stroke.”

Source: University of East Anglia

Even Moderate Physical Fitness Protects Against Atrial Fibrillation and Stroke

Photo by Barbara Olsen on Pexels

A study in more than 15 000 people has found that even moderate physical fitness is linked with a lower likelihood of developing atrial fibrillation and stroke. Progressively higher levels of fitness also reduced the risk of cardiovascular events. The research is presented at ESC Congress 2023.

Atrial fibrillation is the most common heart rhythm disorder, and patients with the condition have a five-fold higher risk of stroke than their peers. This study examined whether fitness was related to the likelihood of developing atrial fibrillation.

The study included 15 450 individuals without atrial fibrillation who were referred for a treadmill test between 2003 and 2012. The average age was 55 years and 59% were men. Fitness was assessed using the Bruce protocol, where participants are asked to walk faster and at a steeper grade in successive three-minute stages. Fitness was calculated according to the rate of energy expenditure the participants achieved, which was expressed in metabolic equivalents (METs).

Participants were followed for new-onset atrial fibrillation, stroke, myocardial infarction and death. The researchers analysed the associations between fitness and atrial fibrillation, stroke and major adverse cardiovascular events (MACE; a composite of stroke, myocardial infarction and death) after adjusting for factors that could influence the relationships including age, sex, cholesterol level, kidney function, prior stroke, hypertension and medications.

During a median of 137 months, 515 participants (3.3%) developed atrial fibrillation. Each one MET increase on the treadmill test was associated with an 8% lower risk of atrial fibrillation, 12% lower risk of stroke and 14% lower risk of MACE.

Participants were divided into three fitness levels according to METs achieved during the treadmill test: low (less than 8.57 METs), medium (8.57 to 10.72) and high (more than 10.72). The probability of remaining free from atrial fibrillation over a five-year period was 97.1%, 98.4% and 98.4% in the low, medium and high fitness groups, respectively.

Study author Dr Shih-Hsien Sung of the National Yang Ming Chiao Tung University, Taipei, Taiwan said: “This was a large study with an objective measurement of fitness and more than 11 years of follow up. The findings indicate that keeping fit may help prevent atrial fibrillation and stroke.”

Source: European Society of Cardiology

Stressful Life Events Contribute to Atrial Fibrillation Risk in Postmenopausal Women

Photo by Karolina Grabowska on Pexels

An estimated 1 in 4 postmenopausal women may develop atrial fibrillation in their lifetime, with stressful life events and insomnia being major contributing factors, according to new research published in the Journal of the American Heart Association.

Atrial fibrillation may lead to blood clots, stroke, heart failure or other cardiovascular complications. It primarily affects older adults.

“In my general cardiology practice, I see many postmenopausal women with picture perfect physical health who struggle with poor sleep and negative psychological emotional feelings or experience, which we now know may put them at risk for developing atrial fibrillation,” said lead study author Susan X. Zhao, M.D., a cardiologist at Santa Clara Valley Medical Center in California. “I strongly believe that in addition to age, genetic and other heart-health related risk factors, psychosocial factors are the missing piece to the puzzle of the genesis of atrial fibrillation.“

Researchers reviewed data from more than 83 000 questionnaires by women ages 50-79 from the Women’s Health Initiative, a major US study. Participants were asked a series of questions in key categories: stressful life events, their sense of optimism, social support and insomnia. Questions about stressful life events addressed topics such as loss of a loved one; illness; divorce; financial pressure; and domestic, verbal, physical or sexual abuse. Questions about sleeping habits focused on if participants had trouble falling asleep, wake up several times during the night and  overall sleep quality, for example. Questions about participants’ outlook on life and social supports addressed having friends to talk with during and about difficult or stressful situations; a sense of optimism such as believing good things are on the horizon; and having help with daily chores.

During approximately a decade of follow-up, the study found:

  • About 25% or 23 954 women developed atrial fibrillation.
  • A two-cluster system (the stress cluster and the strain cluster).
  • For each additional point on the insomnia scale, there is a 4% higher likelihood of developing atrial fibrillation. Similarly, for each additional point on the stressful life event scale, there is a 2% higher likelihood of having atrial fibrillation.

“The heart and brain connection has been long established in many conditions,” Zhao said. “Atrial fibrillation is a disease of the electrical conduction system and is prone to hormonal changes stemming from stress and poor sleep. These common pathways likely underpin the association between stress and insomnia with atrial fibrillation.”

Researchers noted that stressful life events, poor sleep and feelings, such as depression, anxiety or feeling overwhelmed by one’s circumstances, are often interrelated. It’s difficult to know whether these factors accumulate gradually over the years to increase the risk of atrial fibrillation as women age.

Chronic stress has not been consistently associated with atrial fibrillation, and the researchers note that a limitation of their study is that it relied on patient questionnaires from the start of the study. Stressful life events, however, though significant and traumatic, may not be long lasting, Zhao notes. Further research is needed to confirm these associations and evaluate whether customised stress-relieving interventions may modify atrial fibrillation risk.

Source: EurekAlert!

Five Years of High-dose Vitamin D Reduced Atrial Fibrillation Risk

Photo by Michele Blackwell on Unsplash

Taking higher-than-recommended doses of vitamin D for five years reduced the risk of atrial fibrillation in older adults, according to a randomised controlled study conducted in Finland and published in the American Heart Journal.

Atrial fibrillation is the most common arrhythmia, the risk of which increases with age, and which is associated with an increased risk of stroke, heart failure and mortality. Vitamin D has been shown to have an effect, for example, on the atrial structure and the electrical function of the heart, suggesting that vitamin D might prevent atrial fibrillation.

Conducted at the University of Eastern Finland in 2012–2018, the main objective of the Finnish Vitamin D Trial (FIND) was to explore the associations of vitamin D supplementation with the incidence of cardiovascular diseases and cancers. The five-year study involved 2 495 participants, men aged 60 and older, and women aged 65 and older, who were randomised into three groups: one placebo group and two vitamin D3 supplementation groups, with one of the groups taking a supplement of 40µg (1600 IU) per day, and the other a supplement of 80µg (3200 IU) per day. All participants were also allowed to take their personal vitamin D supplement, up to 20µg (800 IU) per day, which at the beginning of the study was the recommended dose for this age group. Participants had no diagnoses of cardiovascular disease or cancer at baseline, and they completed comprehensive health-related questionnaires, both at the beginning. Data on the occurrence of diseases and deaths were also obtained from Finnish nationwide health registers. Approximately 20% of participants were randomly selected for more detailed examinations and blood samples.

During the five-year study, 190 participants were diagnosed with atrial fibrillation: 76 in the placebo group, 59 in the 40µg group, and 55 in the 80 micrograms group. The risk of atrial fibrillation was 27% lower in the 40µg group, and 32% lower in the 80 micrograms group, when compared to the placebo group. In the sub-cohort selected for more detailed examinations, the mean baseline serum calcidiol concentration, which is a marker of the body’s vitamin D concentration, was relatively high, 75nmol/l. After one year, the mean calcidiol concentration was 100nmol/L in the 40µg group, and 120nmol/l in the 80µg group. No significant change in the calcidiol concentration was observed in the placebo group.

Only two randomised trials tried to test whether vitamin D supplementation reduces AF risk in healthy adults, and they did not observe an effect when using doses of 10µg (400 IU) or 50µg (2000 IU) per day. Further confirmation of the present results from the FIND study is therefore needed before doses of vitamin D that significantly exceed current recommendations can be recommended for preventing atrial fibrillation. The FIND study has previously published findings showing no association with the incidence of other cardiovascular events or cancers.

Source: University of Eastern Finland

Can We Use Light Instead of Shocks to Treat Atrial Fibrillation?

Photo by Olivier Collet on Unsplash

New research published in the Journal of Internal Medicine demonstrates that optogenetics, a technique which uses light-sensitive proteins to control the activity of targeted cells. is a promising shock-free approach to treating atrial fibrillation (AF), or an irregular, often rapid heart rate, for immediate restoration of regular rhythm.

Current treatments for AF, which include medications and shocks to restore a regular heart rhythm, come with low success rates and/or serious side effects. In this new study, rats’ hearts were optogenetically modified to express light-gated ion channels. After AF was induced, the animals’ chests were illuminated resulting in acute restoration of regulation rhythm. This shows that sufficient light penetrated the chest wall, which suggests that full penetration of the human atrial wall may be feasible as well, if deemed necessary for clinical translation.

“Shock-free cardioversion of AF would allow restoration of regular rhythm at any place and time, which may improve the prognosis and quality of life of patients suffering from AF. We hope that our paper will contribute to the realization of this much desired option in clinical practice,” said corresponding author Daniël A. Pijnappels, PhD, of Leiden University Medical Center, in The Netherlands.

Source: Wiley