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6th June 2024
A new study has demonstrated a ‘clear correlation’ between atrial fibrillation and vascular dementia, as well as a much higher risk of developing stroke or a major blood clot than those without the heart condition.
Researchers at the University of Birmingham found that individuals with atrial fibrillation, who were considered low-risk patients, had a 68% higher chance of developing vascular dementia than patients without the heart condition. There was however no correlation with the development of Alzheimer’s disease.
The research also found that the low-risk patients had double the chance of developing a stroke or major blood clot than those without atrial fibrillation and suggest that a thromboembolic mechanism is contributing to the development of vascular dementia in patients with atrial fibrillation.
This adds to existing evidence that the heart condition is associated with strokes and blood clots in older patients and those with other health conditions.
The findings, published in the journal Nature Medicine, highlight an additional consequence of this common heart condition, which the researchers advise clinicians to be aware of and attempt to prevent, particularly amongst younger, lower risk patients.
Patients with atrial fibrillation are typically given anticoagulants as stroke prevention therapy but younger patients and those otherwise perceived as ‘low-risk’ are not prescribed the blood thinning medication.
The study was a UK population-based analysis using electronic healthcare records from 5,199,994 primary care patients collected between 2005 and 2020. Just over 5% (290,525) of the patients analysed, who were all between the ages of 40 and 75, had a diagnosis of atrial fibrillation.
The researchers focused on 36,340 of these patients who were not receiving anticoagulation therapy and were considered low-risk based on a standard risk score (CHA2DS2-VASc score <2). The team compared these patients’ outcomes with those of 117,298 control patients without atrial fibrillation, who were matched for age, sex and region.
Rates of death and thromboembolic outcomes, including vascular dementia, during the study were substantially increased in the patients with atrial fibrillation despite their low-risk status.
In the five-year follow up period, 3.8% of patients with atrial fibrillation had a stroke compared with 1.5% of those without the heart condition. Meanwhile, 5.6% versus 2.7% developed ischaemic heart disease, respectively. All-cause mortality was also increased in those with atrial fibrillation, at 8.9% versus 5% for those without.
Adjusting for various potential contributing factors, the authors found atrial fibrillation was associated with a two-fold increased risk of stroke and 1.9-fold increased risk of ischaemic heart disease.
Atrial fibrillation was also associated with an increased rate of all-cause dementia (1.2% versus 0.7% in those without). The report this was driven by vascular dementia cases (0.4% versus 0.1%, respectively), and that those with atrial fibrillation had a 1.68-fold increased risk of developing vascular dementia compared to those without after adjusting for other factors.
Alastair Mobley, a PhD researcher at the University of Birmingham and first author of the study, said: ‘This study demonstrates a clear correlation between AF and vascular dementia. This may have a similar mechanism to the association between AF and stroke.’
The prevention of thromboembolism in atrial fibrillation is typically restricted to older patients or those with specific risk factors and currently does not consider outcomes such as vascular dementia. Ongoing clinical trials such as DaRe2THINK are exploring whether anticoagulants in lower-risk patients can provide a way to prevent the increased risk of thromboembolic outcomes, including vascular dementia.
Dipak Kotecha, professor of cardiology at the University of Birmingham and senior author of the study, added: ‘Atrial fibrillation is one of the most common heart conditions. With its prevalence continuing to rise, it is crucial that we develop strategies to prevent not only stroke but outcomes like dementia, which are a big concern for patients and healthcare systems. Our research highlights the urgency of addressing AF comprehensively, considering its overall impact on the wellbeing of patients.’
A version of this article was originally published by our sister publication Nursing in Practice.
16th April 2024
Treating atrial fibrillation with catheter or surgical ablation is the subject of a new international consensus statement presented at the recent European Heart Rhythm Association (EHRA) Congress 2024.
Also published in the journal EP Europace, among others, the consensus statement sets out best practice standards and defines a contemporary framework for the selection and preprocedural, procedural and postprocedural management of patients considered for, or undergoing, catheter or surgical atrial fibrillation ablation.
It outlines atrial fibrillation pathophysiology, anatomical considerations, evaluation and management of complications, training, and institutional requirements for atrial fibrillation ablation.
And it also highlights the importance of active and healthy lifestyles in reducing the risk of developing atrial fibrillation and to lower the number of recurrences.
The consensus statement was developed by the EHRA, a branch of the European Society of Cardiology which chaired the process; the Heart Rhythm Society; the Asia Pacific Heart Rhythm Society; and the Latin American Heart Rhythm Society.
Lead author Dr Stylianos Tzeis, head of cardiology clinic and electrophysiology and pacing department at the Mitera Hospital in Athens, Greece, noted that technological innovations have made catheter ablation safer and more effective than ever before, with pulsed field ablation and intracardiac echocardiography revolutionising the procedure.
He said: ‘Ablation is the most effective way to prevent recurrences of atrial fibrillation and delay progression to more advanced forms. Pioneering techniques have emerged since the previous consensus in 2017, requiring new advice on who should receive this procedure and how to perform it in the safest and most effective manner.’
The consensus statement emphasises that it ‘is not intended as a guideline’ but ‘aims to document the current expert consensus in the dedicated narrow field of catheter and surgical AF ablation’.
It adds: ‘Healthcare professionals should refer to the latest guidelines for overall structured management of [atrial fibrillation] patients.’
15th April 2024
Any level of passive smoking universally elevates the risk of atrial fibrillation, according to new research presented at the recent European Heart Rhythm Association Congress 2024.
The researchers examined the association between secondhand smoke exposure and the long-term risk of incident atrial fibrillation, aiming to add to existing research that has established links between passive smoking and coronary artery disease and premature death.
They found a dose-dependent relationship between passive smoking duration and atrial fibrillation risk, with each increase in the duration of weekly passive smoking linked with an even greater risk of atrial fibrillation.
The study included 400,493 adults aged 40-69 years (55.2% women) who had used the NHS for any reason and were enrolled in the UK Biobank. Current smokers and those with atrial fibrillation at baseline were excluded from the study.
A touchscreen questionnaire was used to ask participants the number of hours they had been exposed to other people’s smoke in a typical week over the past year at home and in other environments.
Participants were then categorised into the ‘exposed group’ if they had any contact with secondhand smoke and the ‘non-exposed group’ if they had no contact with secondhand smoke.
Some 85,984 (21%) participants had been exposed to secondhand smoke in the previous year, with an average exposure of 2.2 hours per week. During a median follow-up of 12.5 years, atrial fibrillation developed in 23,471 (6%) participants.
After adjusting for factors that could potentially affect the relationship, the group exposed to secondhand smoke had a 6% higher risk of incident atrial fibrillation during follow-up compared with the non-exposed group (hazard ratio 1.06, 95% confidence interval 1.03–1.10, p <0.001).
A dose-dependent relationship was observed, with 7.8 hours of passive smoking per week associated with an 11% higher likelihood of the heart rhythm disorder compared with no passive smoking.
The risk of atrial fibrillation for passive smokers was found to be raised in homes and workplaces as well as in outside spaces.
‘According to our study, once exposed to secondhand smoke, the likelihood of developing atrial fibrillation begins to increase, with the risk escalating significantly as the exposure time lengthens,’ said study author Dr Kyung-Yeon Lee of Seoul National University Hospital, Seoul, Republic of Korea.
‘The dangers of secondhand smoke were significant regardless of whether individuals were at home, outdoors or at work, indicating that exposure universally elevates the risk of atrial fibrillation.’
The authors said the results highlight the importance of smoking bans to protect public health and Dr Lee added that everyone should ‘make every effort to avoid spending time in smoky environments’.
He also urged policymakers to take note and ‘further curb smoking in public areas and support smoking cessation programmes to improve public health’.
In March 2023, the Federation of the Royal Colleges of Physicians in the UK warned of ‘significant and avoidable’ demand on NHS due to socio-economic inequalities, which included the impact of smoking.
Last year, questions were raised over whether the risk of atrial fibrillation increased with fish oil supplementation.
4th September 2023
Individuals with a greater exercise capacity have a reduced risk of developing atrial fibrillation (AFib), ischaemic stroke and major adverse cardiovascular events (MACE), according to the findings of a large study presented at the European Society of Cardiology (ESC) Congress, 2023.
AFib is the most common cardiac arrhythmia and has a number of different causes including auto-immune diseases such as rheumatoid arthritis.
Whether being physically fit might reduce the risk of developing AFib is unclear, although some evidence reveals a graded, inverse relationship between cardiorespiratory fitness and incident AFib, especially among obese individuals.
The study included 15,450 individuals without AFib who had a mean age of 54.9 years (59% male). All participants were referred for a treadmill test between 2003 and 2012.
Fitness was assessed using the Bruce protocol, where participants are asked to walk faster and at a steeper grade in successive three-minute stages. It was then calculated according to the rate of energy expenditure the participants achieved, which was expressed in metabolic equivalents (METs).
Participants were then divided into three fitness levels according to the 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 researchers looked for independent associations between exercise capacity on the treadmill and the risk of new-onset AFib, risk of ischaemic stroke and MACE. The results were adjusted for potential confounders including age, sex, cholesterol level, kidney function, prior stroke, hypertension and any medications.
During the period of follow-up, new-onset AFib occurred in 3.33% of participants.
In fully adjusted models, each one MET increase in exercise treadmill testing, there was an associated 8% lower risk of AFib incidence (hazard ratio, HR = 0.92, 95% CI 0.88 – 0.97).
In addition, this one MET increase was also associated with a lower risk of ischaemic stroke (HR = 0.88, 95% CI 0.83 – 0.94) and a 14% reduced risk of MACE (HR = 0.86, 95% CI 0.84 – 0.88).
In fact, the probability of remaining free from AFib over a five-year period was calculated to be 97.1%, 98.4% and 98.4% in the low, medium and high exercise capacity groups, respectively.
Study author Dr Shih-Hsien Sung of the National Yang Ming Chiao Tung University in 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.‘
25th July 2023
Researchers have identified that a particular gene highly over-expressed in macrophages during atrial fibrillation (AFib) could serve as a future therapeutic target.
AFib leads to disrupted contraction of the atria, increasing the risk of both a stroke and heart failure. Now, a research study led by investigators at Massachusetts General Hospital (MGH) and published in the journal Science, shows that macrophage immune cells appear to have an important role in the development of AFib.
Their study was able to decipher how immune and stromal cells contribute to the arrhythmia. The team compared atrial tissue from patients with and without AFib and developed a mouse model of AFib which integrated hypertension, obesity and mitral valve regurgitation (HOMER) in which these cellular and transcriptomic changes were recapitulated.
Using single-cell transcriptomes from human atria, researchers found inflammatory monocyte and SPP1+ macrophage expansion in atrial fibrillation. In addition, gene expression analyses showed that, in both human and mouse hearts, the SPP1 gene is highly over-expressed in macrophages during AFib. The gene produces a protein called SPP1 protein which promotes tissue scarring and is elevated in the blood of patients with AFib. In contrast, in the HOMER mice model, there were a reduced numbers of atrial macrophages when SPP1 was absent.
Through the use of cell-cell interaction analysis, it was revealed how SPP1 provided a pleiotropic signal that promoted atrial fibrillation through cross-talk with local immune and stromal cells. Moreover, the deletion of SPP1 in HOMER mice reduced AFib, which suggests that SPP1+ macrophages could serve as a target for immunotherapy in patients with atrial fibrillation.
Commenting on the research, senior author Matthias Nahrendorf from Massachusetts General Hospital, said: ‘We found that recruited macrophages support inflammation and fibrosis, or scarring, of the atria, which hinder electrical conduction between heart cells and lead to AFib. Inhibiting macrophage recruitment reduced AFib.
‘We think that this research lays the groundwork for immunomodulatory therapy of AFib, and we are currently working on several strategies to make this happen.‘
1st June 2023
SGLT-2 inhibitor use in people with both diabetes and atrial fibrillation reduces the risk of ischaemic strokes, according to the results of a longitudinal follow‐up study.
Atrial fibrillation (AF) is the most common global cardiac arrhythmia, affecting over three million people. Having AF increases the risk of ischaemic stroke with this risk stratified by the CHA2DS2-VASc score. Fasting hyperglycaemia is a risk factor for AF although the use of sodium-glucose cotransporter-2 (SGLT-2) inhibitors reduces this risk.
The researchers considered whether SGLT-2 inhibitors could therefore reduce the risk of ischaemic stroke in diabetics with AF. Published in the Journal of the American Heart Association, the Taiwanese study followed a group of patients with both diabetes and AF who were prescribed either empagliflozin or dapagliflozin. These individuals were propensity matched to non-users and the incidence of ischaemic strokes documented over the next five years.
A total of 6,614 patients, 801 prescribed one of the SGLT-2 inhibitors, had usable data for analysis.
After five years, 809 patients with diabetes and AF developed an ischaemic stroke. However, the rate was significantly lower among SGLT-2 inhibitor users (p = 0.021).
As expected, there was an increased risk of stroke per one-point increase CHA2DS2‐VASc score (hazard ratio, HR = 1.24, 95% CI 1.20 – 1.29, p < 0.001). Adjusting for the CHA2DS2‐VASc score lowered the stroke risk by 20% among SGLT-2 inhibitor users (HR= 0.80, 95% CI 0.64 – 0.99, p = 0.043).
The findings prompted the authors to suggest clinicians upgrade SGLT-2 inhibitors for glycaemic control, especially in those with co-existing AF.
26th April 2023
The risk of different types of strokes is significantly lower in patients with atrial fibrillation who use who use one of the statin drugs.
Atrial fibrillation (AF) represents the most frequent cardiac arrhythmia. Data from 2017 suggests that globally, the condition affects 3.046 million people. Moreover, AF leads to a five-fold increase in stroke risk with up to 30% of these due to the arrhythmia.
In data presented at EHRA 2023, the risk of strokes was lower in AF patients using statins within a year of their diagnosis. While it is already known that statin use in AF reduces the risk of all-cause mortality. But whether the drugs reduce stroke risk is uncertain.
However, some data suggests that high intensity statins may reduce cerebral events in patients with acute ischaemic stroke and AF.
In the study at EHRA 2023, researchers from Hong Kong, examined a cohort of newly diagnosed AF patients. Individuals were either statin or non-statin users in relation to their AF diagnosis. For instance, a statin user was taking the drug before their AF diagnosis.
The primary outcome was any form of stroke, e.g., ischaemic, systemic embolism, haemorrhagic or a transient ischaemic attack (TIA).
A total of 51,472 AF patients of whom, 11,866 were receiving a statin had analysable data.
During a median follow-up of 5.1 years, among statin users, the ischaemic stroke and systemic embolism risk was 17% lower than non-users (Hazard ratio, HR = 083, 95% CI 0.78 – 0.89). The risk of a haemorrhagic stroke (HS) was 7% lower (HR = 0.93) and the TIA risk 15% lower (HR = 0.85).
Use of statins for 6 years would reduce the risk of an ischaemic stroke or system embolism by 43% compared to use for less than 2 years (HR = 0.57). This risk was also lower for the other cerebral events.
6th April 2023
In a study using deep learning-enabled image segmentation of cardiac magnetic resonance imaging data, US researchers identified how variation in the left ventricle (LV) sphericity index in otherwise normal hearts, predicts the risk for cardiomyopathy and related outcomes such as atrial fibrillation.
Dilation of cardiac chambers and or a decline in systolic function are key indicators of disease and which can be assessed using conventional imaging modalities to quantify such changes. Moreover, deep neural networks have shown a great potential in image pattern recognition and automated methods achieve a performance on par with human experts in analysing cardiovascular magnetic resonance images and deriving clinically relevant measures. Cardiomyopathies of different aetiologies can often result in a similar end-stage phenotype of a more round, spherical ventricle. In fact, in patients with cardiac diseases, a greater sphericity of the left ventricle, has, for example, been shown to be an independent predictor of 10-year survival following an acute myocardial infarction. In the current study, researchers thought that even among those with normal heart function, there was likely to be variation in cardiac sphericity, in particular, sphericity of the left ventricle and that this may serve as marker of cardiac risk, especially among those with an underlying genetic risk.
Using automated deep-learning segmentation of cardiac magnetic resonance imaging (MRI) data, the researchers estimated and analysed the sphericity index in patients who were part of the UK Biobank database but excluded those with either abnormal left ventricular size or systolic function.
Cardiac sphericity and risk of cardiomyopathy
In a total of 38,897 participants, the researchers calculated that for one standard deviation increase in the sphericity index, or roundness of the heart, there was an associated 47% increased incidence of cardiomyopathy (hazard ratio, HR = 1.47, 95% CI 1.10 – 1.98, p = 0.01). In addition, the same increase in the sphericity index, was associated with a 20% increased incidence of atrial fibrillation (HR = 1.20, 95% CI 1.11 – 1.28, p < 0.001) and which was independent of clinical factors and traditional magnetic resonance imaging (MRI) measurements. In contrast, similar increases in the sphericity index were non-significantly associated with the risk of both heart failure (p = 0.3) and cardiac arrest (p = 0.70).
The team also identified four loci associated with sphericity at genome-wide significance and concluded that the variation in left ventricular sphericity in otherwise normal hearts, predicts the risk for cardiomyopathy and related outcomes and is caused by non-ischaemic cardiomyopathy.
Citation
Vukadinovic M et al. Deep learning-enabled analysis of medical images identifies cardiac sphericity as an early marker of cardiomyopathy and related outcomes. Med 2023
30th March 2023
An augmented, double wide-area circumferential catheter ablation (WACA) was no better than the standard single WACA for the prevention of atrial fibrillation (AF) recurrence in patients with paroxysmal AF, according to a randomised trial by Canadian researchers.
The proportion of patients affected by AF varies with age, is slightly more common in men and according to one European study, the prevalence ranged from 0.12 – 0.16% in those under 49 years of age to between 10 and 17% in those 80 years and older. While anti-arrhythmic drugs are effective, among patients with paroxysmal AF who have not tried such drugs, radio-frequency ablation results in a lower rate of recurrent atrial tachyarrhythmias after 2 years. Ectopic beats from the pulmonary veins (PV) often trigger AF and hence catheter ablation approaches have focused on PV isolation (PVI). However, PV electrical reconnection is frequently detected in subjects experiencing recurrent arrhythmia and relatively common, affecting affecting 58% of AF-free patients. Given this high level of AF recurrence, in the current study, the Canadian team wondered if an augmented double wide-area circumferential ablation, i.e., that included a wider area of atrial ablation, might be more effective than the standard, single WACA.
The researchers randomised patients 18 years and older with symptomatic paroxysmal AF, in a 1:1 fashion, to receive radio-frequency catheter ablation for pulmonary vein isolation with either a standard single WACA or an augmented double WACA. The primary outcome was atrial tachyarrhythmia (including atrial tachycardia, atrial flutter, or AF, lasting longer than 30 seconds) recurrence between 91 and 365 days post-ablation.
Augmented vs standard ablation outcomes
A total of 398 patients with a mean age of 61 years (32.9% female) were randomised to the single WACA or control arm (195) or the double WACA arm (203).
In total, 26.7% in the single WACA arm and 24.6% in the double WACA arm had recurrent AA at 1 year (relative risk, RR = 0.92 95% CI 0.66 – 1.29, p = 0.64). Furthermore, a similar proportion in both arms (10.3% vs 7.4%, single vs double WACA) underwent repeated catheter ablation (RR = 0.72, 95% CI 0.38 – 1.36).
There were also no differences in the level of serious adverse events (6.7% vs 6.9%, single vs double WACA).
The authors concluded that additional ablation by performing a double ablation lesion set did not result in improved freedom from recurrent AA compared with a standard single ablation set.
Citation
Nair GM et al. Standard vs Augmented Ablation of Paroxysmal Atrial Fibrillation for Reduction of Atrial Fibrillation Recurrence: The AWARE Randomized Clinical Trial. JAMA Cardiol 2023
18th February 2023
Having autoimmune diseases (AIDs) seems to increase the risk of developing atrial fibrillation according to the findings of a prospective study by Dutch researchers.
Atrial fibrillation (AF) is the most common cardiac arrhythmia and data from 2017 suggests that globally, there were 3.046 million new cases.
Although the underlying cause of AF remains uncertain, there is a suggestion of a mechanistic link with inflammatory processes. Moreover, a feature of autoimmune diseases such as rheumatoid arthritis is inflammation and one meta-analysis found a 29% higher risk of AF among those with rheumatoid arthritis. Nevertheless, the link between AF and other autoimmune disorders is less clear.
As a result, in the current study, the Dutch team turned to data held in the UK Biobank and looked for those diagnosed rheumatic fever, gastrointestinal AIDs and other AIDs e.g. those affecting the musculoskeletal, connective tissues and neurological systems. Such individuals were monitored over time for the development of AF. In addition, the team collected data on cardiovascular risk factors such as hypertension, type 2 diabetes, body mass index etc and which were adjusted for in regression models.
A total of 494,072 individuals with a median age of 58 (54.8% female) were followed for a median of 12.8 years and during this time 5.5% of the cohort developed AF.
In fully adjusted models, among those with rheumatic fever but no cardiac involvement, there was a 47% higher risk of developing AF (hazard ratio, HR = 1.47, 95% CI 1.26 – 1.72).
Similarly, there were elevated risks for those with several autoimmune diseases including Crohn’s disease (HR = 1.23), ulcerative colitis (HR = 1.17), rheumatoid arthritis (HR = 1.39) systemic lupus erythematosus (HR = 1.82) and systemic sclerosis (HR = 2.32).
When analysed by gender, the researchers found that for many of these disorders, there was a higher risk among women although the risk was higher among men but only for ulcerative colitis.
The authors concluded that whilst their data showed how autoimmune diseases were associated with the development of AF, further evidence was need to support the clinical translation of these findings.
Citation
Tilly MJ et al. Autoimmune diseases and new-onset atrial fibrillation: a UK Biobank study. Eurospace 2022.
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