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3rd February 2023
Delaying the use of catheter ablation for those with atrial fibrillation (AF) and or heart heart failure, leads to worse cardiovascular outcomes such as mortality, stroke and AF recurrence according to an analysis by US researchers.
AF is the most clinically significant arrhythmia in practice, affecting between 1 and 3% of the population though this rises to 17% in those 80 years of age and older. AF often co-exists with heart failure and the presence of both conditions, exerts a major detrimental effect on patient’s cardiovascular health and overall wellbeing. Atrial fibrillation can be managed medically with anti-arrhythmic drugs although catheter ablation therapy is also an option. However, a recent study has indicated that among AF patients with stable heart failure, the use of catheter ablation was superior, with respect to survival, freedom from AF recurrence and quality of when compared to drug treatment. With clearly beneficial effects from ablation therapy, one unanswered question is when the ablation should be undertaken in relation to the AF diagnosis. In other words, might delaying catheter ablation, affect the subsequent risk of death or other outcomes such as hospitalisation for heart failure. In a 2013 study, researchers found that delaying ablation worsened the success of the procedure. Moreover, does the impact of any delay affect patients with differing levels of heart failure, based on the extent of left ventricular dysfunction? This was the subject of the current study by the US team.
Researchers studied patients with at least 12 months follow-up data following their ablation procedure and who were then stratified based on their ejection fraction as either < 35% or > 35%. The team then compared several adverse outcomes such as mortality, heart failure (HF) hospitalisation and AF recurrence in relation to the delay between the initial AF diagnosis and the time of ablation. These delays were categorised as 30 – 180 days, 181 – 454 days, 546 – 1825 days or > 1825 days.
Catheter ablation delay and adverse outcomes
Data were available for 9,979 patients with the overall time delay between diagnosis and the first ablation being a median of 2 years and this figure was not significantly different between the two categories of ejection fraction (p = 0.66).
When considering patients with an ejection fraction > 35%, a delay of 181 – 545 days (compared to 30 – 180 days) was associated with a significantly higher mortality risk (hazard ratio, HR = 2.02 (95% CI 1.38 – 2.96) and this risk was more than double, among those waiting longer than 1825 days (HR = 4.39). In addition, there were elevated risks for HF hospitalisations and AF recurrence incurred by delaying ablation therapy.
Among those with an ejection fraction < 35%, there were also elevated risks of mortality, HF hospitalisation and AF recurrence associated with ablation delays, e.g. HR = 3.77 for mortality.
The authors concluded that catheter ablation delays among those with AF increased the risks for adverse events in patients either with or without structural heart disease, highlighting the need for earlier ablation therapy.
Sessions AJ et al. Increasing time between first diagnosis of atrial fibrillation and catheter ablation adversely affects long-term outcomes in patients with and without structural heart disease. J Cardiovasc Electrophysiol 2023
18th November 2022
A model combining features of an ECG and radiomics data derived from cardiovascular magnetic resonance imaging improved the detection of atrial fibrillation (AF) in women to a greater extent than either model alone according to the findings of a study by Spanish and UK researchers.
Atrial fibrillation is the most common cardiac arrhythmia, characterised by an irregular heart rhythm and an often abnormally rapid heart rate and globally has been estimated to affect 0.51% of the population. AF is diagnosed from an ECG in which typically, P-waves are absent and there is both a chaotic baseline and an irregular ventricular rate. Cardiac magnetic resonance (CMR) is the reference imaging modality for assessment of cardiac structure and function and CMR radiomics has the potential to improve diagnostic accuracy. Moreover, Cardiac MRI of the atrial substrate is not only a tool for management and treatment of arrhythmia, but also to individualise the prevention of stroke and major cardiovascular events. But what remains unclear is whether the use of a CMR-based radiomics model can identify patients with AF and more importantly, if addition of a model that uses ECG-derived data, would further enhance the potential to detect AF.
In the present study, researchers examined the feasibility of combining a CMR-derived radiomics model and one based on ECG data. The team used information from the UK Biobank and identified patients who had both an ECG and CMR scan and compared their findings with healthy controls. Models were assessed using the area under the receiver operating characteristics curve (AUC) and associated sensitivity and specificity.
ECG and radiomics model and atrial fibrillation detection
A total of 32,121 participants with a mean age of 63 years (51% female) were included and of whom, 495 (63% male) had AF.
Overall, the AUC for the combined model was similar to the ECG-model (0.87 vs 0.86), i.e., adding the radiomics model did not significantly improve predictive power. In fact, when comparing the predictive power of models between the sexes, the AUC for the ECG-model was less predictive for women than men (0.77 vs 0.88, p < 0.05). However, although accuracy improved for women when combined with the CMR-model, but this only improved to the level of the ECG-model for men (0.87 vs 0.88, women vs men). Finally, when considering AF patients who had a normal ECG, the combined model had an AUC of 0.61.
The authors concluded that their integrative radiomics-ECG model presents a potential novel approach for earlier detection of AF.
Pujadas ER et al. Atrial fibrillation prediction by combining ECG markers and CMR radiomics. Sci Rep 2022
2nd November 2022
The misuse of the illicit substances methamphetamine, cocaine, opiates and cannabis has been found to increase the risk of incident atrial fibrillation (AF) according to the findings of a longitudinal analysis by Californian researchers.
Atrial fibrillation is the most frequent cardiac arrhythmia, and it has been estimated that 6 -12 million people worldwide suffer from the condition. Moreover, the presence of the arrhythmia is also independently associated with a higher risk of all-cause mortality. While it has become well established that a higher intake of alcohol as well as smoking, increases the risk of AF, the relationship with the misuse of illicit drugs is less clear. Whereas prior work has suggested that methamphetamine abuse leads to ECG changes that pose a higher risk for ventricular arrhythmias and most notably torsades de pointes, less is known about the effect on AF. However, there is some data linking an increased risk of AF from use of both cannabis and cocaine though these findings are derived from case studies. But in contrast, one study actually identified how cannabis use was associated with a lower odds of AF.
In the present study, the US researchers sought to determine whether misuse of the illicit substances, methamphetamine, cocaine, opiates and cannabis were a predictor of incident AF. The team used several California healthcare databases, e.g., emergency department and inpatient to capture repeat visits for a given patient. They extracted demographic and co-morbidity data and excluded those with known AF and looked at cases where substance use was considered present at the first healthcare encounter. The researchers then compared the baseline and clinical characteristics of patients for each of the different drugs and examined the association with AF, adjusting for covariates known to be associated with AF.
Illicit substance misuse and incident atrial fibrillation
In a total of 23,561,884 individuals, 98,271 used methamphetamine, 48,701 cocaine, 10,032 opiates and 132,834 cannabis. From this total, 4.2% developed incident AF during the period of study from 2005 to 2015. The mean age of participants ranged from 32.3 years (cannabis) to 41.1 (cocaine) and the proportion of females from 28.3% to 55%.
After adjustment for covariates, methamphetamine use was associated with an 86% higher risk of developing incident AF (Hazard ratio, HR = 1.86, 95% CI 1.81 – 1.92). Similar and significantly elevated risks were seen for cocaine (HR = 1.61), opiates (HR = 1.74) and cannabis (HR = 1.35). Interesting, polysubstance use was also associated with a higher risk of AF compared to single drug misuse (HR = 1.63, 95% CI 1.61 – 1.66).
The authors concluded that for each of the misused substances analysed, there was a higher risk of developing incident AF after controlling for conventional AF risk factors.
Lin AL et al. Cannabis, cocaine, methamphetamine, and opiates increase the risk of incident atrial fibrillation. Eur Heart J 2022
27th October 2022
Intravenous (IV) magnesium and potassium administration to patients with non-permanent atrial fibrillation within an emergency department (ED), has been found to increase the chance of spontaneous return to sinus rhythm according to a registry-based cohort study by Austrian researchers.
Atrial fibrillation (AF) is the most frequent cardiac arrhythmia and in 2017, it was estimated that globally, 3.046 million new cases were registered, leading the authors to conclude that AF incidence and prevalence have increased over the last 20 years and will continue to increase over the next 30 years. Patients with recent onset AF commonly undergo immediate restoration of sinus rhythm by pharmacologic or electrical cardioversion. Despite this practice there is evidence to suggest that because AF can spontaneously resolve, a wait and see strategy is non-inferior to early cardioversion in achieving a return to sinus rhythm at 4 weeks. In the absence of therapy, some work suggests that low serum magnesium and potassium levels below 3.5 mmol/l are both associated with increased risk of AF. But could administration of these two electrolytes to patients presenting at an emergency department (ED) with non-permanent AF, increase the chance of spontaneous conversion to sinus rhythm?
This was the question addressed in a recent study by the Austrian team, The researchers used data held in an Austrian arrhythmia registry within the department of emergency medicine at Vienna General Hospital. They included all adult patients presenting at the ED with either AF or atrial flutter and since there are no guidelines based on the administration of either electrolyte in AF or atrial flutter, use of the electrolytes was at the discretion of the treating physician. A prefabricated electrolyte infusion containing 24 mmol of potassium and 5.9 mmol of magnesium and used and given for 90 minutes. The primary outcome was the probability of spontaneous conversion to sinus rhythm (SCV) during the patient’s stay at the ED.
IV magnesium and potassium and spontaneous conversion to sinus rhythm
A total of 3119 episodes (2546 of non-permanent AF) were included in the analysis in AF patients with a median age of 68 years (55.4% male).
In AF patients, IV magnesium and potassium used produced SCV in 19.2% compared to 10.4% in the no-administration group (odds ratio, OR = 1.98, 95% CI 1.53 – 2.57). In fact, the odds of SCV were much higher among patients with baseline potassium levels < 3.5 mmol (OR = 5.19, 95% CI 1.51 – 17.84).
In contrast to AF, IV magnesium and potassium use was not associated with a higher level of SCV (OR = 1.05, 95% CI 0.65 – 1.69) irrespective of baseline potassium levels among patients with atrial flutter.
The authors concluded that administering IV magnesium and potassium to patients with non-permanent AF was associated with a higher probability of SCV although not for atrial flutter. They added that this approach might reduce the need for anti-arrhythmic therapy and called for future trials to examine the safety and efficacy of their approach.
Cacioppo F et al. Association of Intravenous Potassium and Magnesium Administration With Spontaneous Conversion of Atrial Fibrillation and Atrial Flutter in the Emergency Department JAMA Netw Open 2022
10th October 2022
The worldwide prevalence of atrial fibrillation (AF) was estimated to be 37,574 million cases (0.51% of worldwide population) in 2017 and the authors noted how this has increased by 33% during the last 20 years. However, AF is often asymptomatic and a US-based study estimated that of a total AF prevalence of 5.3 million (in 2009), 0.7 million (13.1% of AF cases) were undiagnosed. Moreover, AF is a major risk factor for strokes and it has been estimated that around 20% of all strokes are caused by the arrhythmia, highlighting the need to identify those affected. AF can be detected with an ECG although patients require intermittent and prolonged monitoring which is labour intensive. In a 2019 study, it was found that an AI-guided screening tool enabled an ECG, acquired during normal sinus rhythm, to identify individuals with atrial fibrillation. Nevertheless, while this important advance was potentially of great clinical value, prior to widespread implementation, there were two further and important questions. Firstly, could the AI-guided screening tool enable risk-stratification that was superior to currently available approaches and secondly, how often or how much monitoring would be required for those deemed to be at a high-risk for AF using the device.
In trying to answer these questions, a team of US researchers, undertook a non-randomised, interventional trial and prospectively recruited patients who had risk factors for a stroke but without AF and who had an ECG. The AI-guided screening tool using just the raw ECG data, determined an individual’s AF risk score which was categorised as either high or low-risk. Eligible participants wore a continuous ambulatory heart rhythm monitor all the time for 30 days and were matched 1:1 to real-world control patients (i.e., a group not wearing the monitor). The primary outcome of interest was newly diagnosed atrial fibrillation, defined as an episode lasting 30 seconds or longer.
AI-guided screening tool and detection of atrial fibrillation
A total of 1003 individuals with a mean age of 74 years (61.8% male) were included in the study, of whom 370 were deemed to be at a low AI assessed risk of AF.
Over a mean of 22.3 days, AF was detected in 1.6% of those deemed to be at low risk and 7.6% deemed to be at high risk (odds ratio, OR = 4.98, 95% CI 2.11 – 11.75, p = 0.0002).
The researchers calculated that AI-guided screening was associated with a significantly higher detection of AF compared to usual care in those deemed at high risk (10.6% vs 3.6%, p < 0.0001). However, the difference was not significant for those deemed at low risk (2.6% vs 1.1%, p = 0.12).
The authors concluded that the AI-guided screening tool was able to risk-stratify patients for AF in the short-term and to provide a higher rate of detection among patients deemed to be at high risk.
Noseworthy PA et al. Artificial intelligence-guided screening for atrial fibrillation using electrocardiogram during sinus rhythm: a prospective non-randomised interventional trial Lancet 2022
7th October 2022
Fish oil supplement use in patients with cardiovascular disease has been shown to provide a small beneficial advantage in terms of mortality and admission to hospital for cardiovascular reasons in patients with heart failure. However, not all studies with fish oils has have been positive. For instance, other data in patients with atherogenic dyslipidaemia and high cardiovascular risk, have found that among statin-treated patients at high cardiovascular risk, the addition of omega-3 fatty acids, resulted in no significant difference in a composite outcome of major adverse cardiovascular events when compared with corn oil. Despite these ambiguous findings with respect to cardiovascular disease, there is some evidence that fish oil supplement use among patients with atrial fibrillation (AF) is beneficial. For example, in one trial among patients with persistent atrial fibrillation on amiodarone and a renin-angiotensin-aldosterone system inhibitor, the addition of fish oil supplementation improved the probability of maintaining sinus rhythm after direct current cardioversion, possibly through prevention of atrial fibrillation recurrence. In contrast, a recent study with both fish oils and vitamin D supplementation observed that compared with placebo, neither supplement had a significant effect on the risk of incident atrial fibrillation over a follow-up of more than 5 years. But when data has been pooled, one 2021 meta-analysis found that fish oil supplement use was associated with an increased risk of AF which was greater in trials testing >1 g/d.
With some evidence to suggest that both monogenic and polygenic factors contribute to AF risk in the general population, in the present study, a team of Australian researchers sought to examine whether habitual fish oil supplement use was associated with the risk of incident AF after adjustment for several factors including individual’s genetic risk score. Using the UK Biobank data, individuals were dichotomised (Yes/No) as habitual fish oil users. After calculation of an AF genetic risk score, individuals were categorised to be at either low, immediate or high genetic risk. The primary outcome of the study was set as incident AF and the researchers also considered the risk of AF in those with and without cardiovascular disease at the study baseline point. The results were adjusted for several factors including age, gender, consumption of oily fish and genetic risk score.
Fish oil supplement use and incident atrial fibrillation
A total of 468,665 individuals with a mean age of 56.5 years (45.2% male) were included in the analysis and followed for a median of 11.1 years.
During the period of follow-up, the risk of developing incident AF was significantly higher among fish oil supplement users (adjusted hazard ratio, aHR = 1.10, 95% CI 1.07 – 1.13, p < 0.0001).
When considering the risk of AF based on genetic risk scores, this was significantly higher for low (HR = 1.08), intermediate (aHR = 1.10) and high risk (aHR = 1.11) fish oil supplement users.
Finally, while there was no increased risk among those with existing cardiovascular disease (CVD), the risk was elevated (aHR = 1.13) among those without CVD at baseline.
The authors concluded that habitual fish oil supplement use was associated with a higher risk of incident atrial fibrillation and that this risk remained regardless of genetic AF risk and consumption of oily fish but was only observed in those without cardiovascular disease.
Zhang J et al. Habitual fish oil supplementation and the risk of incident atrial fibrillation: findings from a large prospective longitudinal cohort study Eur J Prev Cardiol 2022
16th September 2022
An Anticoagulant (AC) pathway for patients with atrial fibrillation seen at an emergency department can be easily and safely implemented before they are discharged home according to the findings of a study by Canadian researchers.
Atrial fibrillation (AF) is the most frequent cardiac arrhythmia and using a Global Health Data Exchange database, a study has revealed that total of 3.046 million global new cases were registered in the database during 2017. This same study also found that the worldwide prevalence of AF was 37,574 million cases (0.51% of worldwide population) and had increased by 33% during the last 20 years. Having AF leads to a 5-fold increased risk of stroke and that 20–30% of all strokes are attributed to the arrhythmia. In the UK, NICE has recommended the use of an anticoagulant for stroke prevention, noting how for most people the benefit of anticoagulation outweighs the bleeding risk. Given the importance of anticoagulation among AF patients, in a review of health records of patients diagnosed with new onset atrial fibrillation in two emergency departments, the Canadian group found that only 17% of 272 patients eligible for initiation of anticoagulation left the emergency department with a prescription for the treatment. Based in these findings, the team introduced the Safe Anticoagulation for Atrial Fibrillation (SAFE) emergency department (ED) pathway, for the initiation of treatment in patients with AF. The SAFE pathway used the CHADS65 risk stratification tool i.e., for which patients with heart failure, hypertension, diabetes, prior stroke or 65 years of age and over, were eligible. The SAFE pathway outlined the contraindications to starting a direct action oral anticoagulant (DOACs), provided patient educational material and a letter for their family doctor. For the study, the team set the primary outcome as the proportion of CHADS65-positive patients, without contra-indications to DOACs who received an AC and patients were followed up over the next 90 days.
Initiation of the anticoagulant pathway
Between 2018 and 2020, a total of 311 patients with a median age of 69 years (48% female) were managed using the SAFE pathway although since 8 were already prescribed an anticoagulant, the final number of patients included was 303.
An AC prescription was offered to 91.4% of the target population (4 declined treatment) and the 90-day anticoagulation status was available for 93% of patients.
Among the target group, 80.9% of patients were still taking their anticoagulant at 90 days and only a single patient was diagnosed with a stroke during this time-frame. Furthermore, the 90-day major bleed rate among those who had started treatment was 0.5%.
The authors concluded that the SAFE pathway facilitated anticoagulation among ED patients with AF at risk of stroke and with a low 90-day adverse event rate.
Kirwan C et al. Starting anticoagulation for atrial fibrillation in the emergency department safely Emerg Med J 2022
5th September 2022
Atrial fibrillation detection with a smartphone-based screening app more than doubles the rate of detection compared to symptom-based, usual care according to the results of a randomised trial by researchers based in Munich, Germany.
Atrial fibrillation (AF) is the most common cardiac arrhythmia and which in 2019, was estimated to have a global burden of 59.7 million. The condition is diagnosed with an electrocardiogram tracing showing AF and while many patients experience symptoms including chest pain, palpitations, shortness of breath, and fatigue, others have no symptoms, a condition referred to as asymptomatic or “silent” AF. The presence of AF increases the risk of a stroke and one meta-analysis found that AF might be newly detected in nearly a quarter of patients with stroke or transient ischaemic attack, highlighting the need for early detection. Although smart device-based photoplethysmography technology could be a feasible approach for AF screening, the extent to which such methods can increase detection compared to usual methods is uncertain.
In the present study, the German team undertook an open-label, randomised trial which compared digital screening (using the smartphone app) or usual care. Eligible patients were all free of AF at baseline and if there were any abnormalities detected via the app (based on pulse irregularities), these were verified using external ECG loop recorders. The study was conducted over a 6-month period and the primary efficacy endpoint was the first diagnosis of treatment-relevant AF and which led to the initiation of oral anticoagulant therapy. The secondary endpoints were newly diagnosed AF, stroke and newly prescribed oral anticoagulants. After the first 6 months, participants crossed over for a second phase of the study with reverse assignment.
Atrial fibrillation diagnoses
A total of 5,551 participants with a mean age of 65 years (31% female) were randomly assigned to digital monitoring (2,860) or usual care. Among the whole cohort, 15% had coronary heart disease and 6% a history of stroke.
Within the first 6 months, the primary endpoint was reached by 1.33% of those in the smartphone group compared to 0.63% in the usual care arm (odds ratio, OR = 2.12, 95% CI 1.19 – 3.76, p = 0.010).
A total of 4,752 individuals for whom the primary endpoint was not reached, crossed over for a second 6-month period. As with the first phase, the proportion achieving the primary endpoint was 1.38% vs 0.51% (OR = 2.75, 95% CI 1.42 – 5.34, p = 0.003).
There were also significant differences for the secondary endpoints of newly diagnosed AF (1.68% vs 0.89%, p = 0.011), newly prescribed anticoagulants (1.71% vs 0.85%, p = 0.006) but not for stroke (p = 0.95).
The authors concluded that smartphone-based screening increases the detection of AF compared to routine-symptom-based screening and suggested that future studies should focus on whether digital screening for AF leads to better treatment outcomes.
Rizas KD et al. Smartphone-based screening for atrial fibrillation: a pragmatic randomized clinical trial Nat Med 2022
1st October 2021
Atrial fibrillation (AF) is the most common arrhythmia diagnosed in clinical practice and an analysis of an international database in 2017 found that a total of 3.046 million new cases were registered. The presence of AF increases the risk of stroke and thus subsequent cognitive impairment but one study also showed that AF is associated with an almost three-fold increased risk of dementia. Moreover, there is a growing body of literature that supports AF as being a risk factor for both cognitive decline and dementia although the mechanisms responsible for this association are diverse and not solely related to the increased risk of stroke.
In trying to understand these associations, a team from the Institute of Neuroscience and Physiology, Sahlgrenska, Gothenburg, Sweden, set out to determine whether AF was associated with cerebrovascular pathologies. The team obtained data from the Gothenburg H70 Birth Cohort Studies, which included individuals born in 1944 who underwent structural brain MRI scans between 2014 – 2017. Using these scans, the team looked for markers of cerebral small vessel disease such as white matter hyper-intensities (WMHs), lacunes, brain infarcts and cerebral micro-bleeds, with the latter two conditions assessed by a radiologist. The patient’s diagnosis of AF was either self-reported or based on electrocardiogram results or data from Sweden’s National Patient Register (NPR). A control group of patients who did not undergo an MRI scan were included for comparative purposes.
A total of 776 participants were included of whom 65 (8.4%) had a diagnosis of AF. The presence of AF was associated with a history of symptomatic stroke (odds ratio, OR = 4.5 95% CI 2.1–9.5), large infarcts (OR = 5.0), lacunes (OR = 2.7) and silent brain infarcts (OR = 3.5). Additionally, individuals with AF had larger WMH volumes than controls, especially those currently treated for AF.
The authors concluded that AF was associated with broad range of cerebrovascular pathologies and called for further work to establish whether cerebrovascular MRI markers could help to complement current treatment guidelines for patients with AF.
Ryden L et al. Atrial Fibrillation, Stroke, and Silent Cerebrovascular Disease: A Population-Based MRI Study. Neurology 2021