Understanding Of Atrial Fibrillation Research Articles

Biomarkers of atrial fibrillation-related pathways and left atrial structure and function in an overweight and obese population.

Exploring longitudinal associations of blood biomarkers with left atrial (LA) structure and function can enhance our understanding of atrial fibrillation (AF) etiopathogenesis. We studied 532 participants of the PREDIMED-Plus trial, a multicenter randomized trial in overweight and obese adults with metabolic syndrome. At baseline, 3 and 5 years after randomization, participants underwent transthoracic echocardiography and provided blood for serum biomarker measurements [propeptide of procollagen type I (PICP), high-sensitivity (hs) troponin T (hsTnT), hs C-reactive protein (hsCRP), 3-nitrotyrosine (3-NT), and N-terminal propeptide of B-type natriuretic peptide (NT-proBNP)]. Outcomes of interest included LA peak systolic longitudinal strain (LA PSLS), LA volume index (LAVi), LA function index (LAFi), and LA stiffness index (LASi). We performed cross-sectional and longitudinal analyses to evaluate relationships between log-transformed biomarkers and echocardiographic measurements using multiple linear regression and mixed models. The participants in this analysis had a mean age of 65.0 (SD 4.8) years, and 40% were females. At baseline, increased NT-proBNP and hsTnT were associated with larger LAVi and worse LA function as measured by the LAFi, LASi, and LA PSLS. Longitudinally, higher NT-proBNP, but not higher hsTnT, was associated with increased LAVi and worsening LA function. Over 5 years, 1 unit increase in log(NT-proBNP) was associated with steeper decline in LA PSLS (-0.19%, 95% CI -0.35%, -0.02%) and greater increase in LAVi (0.28 mL/m2, 95% CI 0.10, 0.45) each year. PICP, hsCRP, and 3-NT did not show consistently significant associations with LA outcomes at baseline and through 5 years. In an overweight and obese population, higher NT-proBNP was associated with LA volume enlargement and worsening LA function over 5 years. The implications of these findings for the prevention and prediction of AF warrant further investigation.

A Systematic Review on the Effectiveness of Machine Learning in the Detection of Atrial Fibrillation.

Recent endeavors have led to the exploration of Machine Learning (ML) to enhance the detection and accurate diagnosis of heart pathologies. This is due to the growing need to improve efficiency in diagnostics and hasten the process of delivering treatment. Several institutions have actively assessed the possibility of creating algorithms for advancing our understanding of atrial fibrillation (AF), a common form of sustained arrhythmia. This means that artificial intelligence is now being used to analyze electrocardiogram (ECG) data. The data is typically extracted from large patient databases and then subsequently used to train and test the algorithm with the help of neural networks. Machine learning has been used to effectively detect atrial fibrillation with more accuracy than clinical experts, and if applied to clinical practice, it will aid in early diagnosis and management of the condition and thus reduce thromboembolic complications of the disease. In this text, a review of the application of machine learning in the analysis and detection of atrial fibrillation, a comparison of the outcomes (sensitivity, specificity, and accuracy), and the framework and methods of the studies conducted have been presented.

An iPS-derived in vitro model of human atrial conduction.

Atrial fibrillation (AF) is the most common arrhythmia in the United States, affecting approximately 1 in 10 adults, and its prevalence is expected to rise as the population ages. Treatment options for AF are limited; moreover, the development of new treatments is hindered by limited (1) knowledge regarding human atrial electrophysiological endpoints (e.g., conduction velocity [CV]) and (2) accurate experimental models. Here, we measured the CV and refractory period, and subsequently calculated the conduction wavelength, in vivo (four subjects with AF and four controls), and ex vivo (atrial slices from human hearts). Then, we created an in vitro model of human atrial conduction using induced pluripotent stem (iPS) cells. This model consisted of iPS‐derived human atrial cardiomyocytes plated onto a micropatterned linear 1D spiral design of Matrigel. The CV (34–41 cm/s) of the in vitro model was nearly five times faster than 2D controls (7–9 cm/s) and similar to in vivo (40–64 cm/s) and ex vivo (28–51 cm/s) measurements. Our iPS‐derived in vitro model recapitulates key features of in vivo atrial conduction and may be a useful methodology to enhance our understanding of AF and model patient‐specific disease.

Should we be screening people with diabetes for atrial fibrillation? Exploring patients' views.

Atrial fibrillation (AF) and diabetes are increasingly prevalent worldwide, both increasing stroke risk. AF can be detected by patient-led electrocardiogram (ECG) screening applications. Understanding patients' views around AF screening is important when considering recommendations, and this study explores these views where there is an existing diagnosis of diabetes. Nine semi-structured qualitative interviews were conducted with participants from a previous screening study (using a mobile ECG device), who were identified with AF. Thematic analysis was completed using NVivo 12 Plus software and themes were identified within each research question for clarity. Themes were identified in four groups: 1. patients' understanding of AF - the 'concept of irregularity' and 'consideration of consequence'; 2. views on screening - 'screening as a resource-intensive initiative', 'fear of outcomes from screening' and 'expectations of screening reliability'; 3. views on incorporating screening into routine care - 'importance of screening convenience'; and 4. views on the screening tool - 'technology as a barrier' and 'feasibility of the mobile ECG recording device for screening'. In conclusion, eliciting patients' views has demonstrated the need for clear and concise information around the delivery of an AF diagnosis. Screening initiatives should factor in location, convenience, personnel, and cost, all of which were important for promoting screening inclusion.

The information needs of patients with atrial fibrillation: A scoping review.

To identify the atrial fibrillation (AF)-specific information needs of patients with AF. Patients' understanding of AF is pertinent to optimising treatment and outcomes, thus highlighting the need for effective patient education. The information required to deliver effective AF-specific patient education is less examined. Guided by Arksey and O'Malley's framework, a scoping review was conducted for studies reporting the AF-specific information needs of patients with AF. Systematic searches were conducted across six databases (Medline, PubMed, CINAHL, Scopus, PsycINFO and ProQuest). All analyses were narrated in prose and outlined in tables. The PRISMA-ScR checklist was used to report this review. The systematic search yielded 3816 articles, of which 22 were included. Three major themes emerged from the thematic analysis. Each theme was supported by three subthemes. First, in 'Understanding AF', patients reported the need for 'Easy-to-understand information', information on the 'Screening and diagnosis' of AF and 'Trajectory of disease and its associated risks'. Second, in 'Treating AF', patients required information on the 'Role of anticoagulation', 'Existing or novel therapeutic options' and 'Monitoring effectiveness of treatment'. Lastly, in 'Living with AF', patients needed education in 'Symptom management', 'Secondary prevention of risks' and 'Recognition of emergency situations'. This review has identified the key AF-specific information needs of patients with AF. Being cognisant of the information needs of patients with AF, healthcare providers may become more effective in developing person-centred patient education interventions. Delivering relevant patient education is an important cornerstone for atrial fibrillation care. Nurses by convention play a professional role in patient education. It may be facilitative for nurses to refer to the review findings when developing and implementing patient education interventions. Being in the midst of an ongoing pandemic, patient education strategies may require the use of telecommunication technologies.

Association Between Permanent Non-Valvular Atrial Fibrillation with Microalbuminuria and C-Reactive Protein

Background: An understanding of atrial fibrillation (AF) mechanisms, as the most common cardiac arrhythmia, is essential for primary and secondary prevention. Some studies indicated an association between microalbuminuria and C-reactive protein (CRP) protein, with the incidence and prevalence of AF. This study aimed to investigate the relationship between permanent non-valvular AF with microalbuminuria and reactive protein C. Materials and Methods: In this case-control study, 40 permanent non-valvular AF patients and 40 non-AF patients (control group) were studied. Demographic data and measurements of albumin, urine creatinine, CRP, and microalbuminuria were recorded and compared between the two groups. Results: In patients with permanent non-valvular atrial fibrillation, CRP level (P<0.001) and microalbuminuria (P=0.012) were significantly higher than the control group. Also, in patients with permanent non-valvular AF, the CRP positive (P = 0.014) and microalbuminuria (P = 0.003) were significantly higher than controls. The results showed that elevated chance of permanent non-valvular AF with abnormal CRP was 4.25 (odds ratio [OR]= 4.25, 95% confidence interval [CI]: 1.18-1.28; P= 0.026), and with microalbuminuria was 6.54 (OR= 6.54, 95% CI: 1.65-25.89; P=0.007). Conclusion: An elevated CRP level and microalbuminuria were significantly associated with permanent non-valvular atrial fibrillation. A longitudinal study is necessary. [GMJ.2021;10:e2106]

Association Between Permanent Non-Valvular Atrial Fibrillation with Microalbuminuria and C-Reactive Protein

Background: An understanding of atrial fibrillation (AF) mechanisms, as the most common cardiac arrhythmia, is essential for primary and secondary prevention. Some studies indicated an association between microalbuminuria and C-reactive protein (CRP) protein, with the incidence and prevalence of AF. This study aimed to investigate the relationship between permanent non-valvular AF with microalbuminuria and reactive protein C. Materials and Methods: In this case-control study, 40 permanent non-valvular AF patients and 40 non-AF patients (control group) were studied. Demographic data and measurements of albumin, urine creatinine, CRP, and microalbuminuria were recorded and compared between the two groups. Results: In patients with permanent non-valvular atrial fibrillation, CRP level (P<0.001) and microalbuminuria (P=0.012) were significantly higher than the control group. Also, in patients with permanent non-valvular AF, the CRP positive (P = 0.014) and microalbuminuria (P = 0.003) were significantly higher than controls. The results showed that elevated chance of permanent non-valvular AF with abnormal CRP was 4.25 (odds ratio [OR]= 4.25, 95% confidence interval [CI]: 1.18-1.28; P= 0.026), and with microalbuminuria was 6.54 (OR= 6.54, 95% CI: 1.65-25.89; P=0.007). Conclusion: An elevated CRP level and microalbuminuria were significantly associated with permanent non-valvular atrial fibrillation. A longitudinal study is necessary. [GMJ.2021;10:e2106]

Analyzing the effect of electrode size on electrogram and activation map properties

BackgroundAtrial electrograms recorded from the epicardium provide an important tool for studying the initiation, perpetuation, and treatment of AF. However, the properties of these electrograms depend largely on the properties of the electrode arrays that are used for recording these signals. MethodIn this study, we use the electrode's transfer function to model and analyze the effect of electrode size on the properties of measured electrograms. To do so, we use both simulated as well as clinical data. To simulate electrogram arrays we use a two-dimensional (2D) electrogram model as well as an action propagation model. For clinical data, however, we first estimate the trans-membrane current for a higher resolution 2D modeled cell grid and later use these values to interpolate and model electrograms with different electrode sizes. ResultsWe simulate electrogram arrays for 2D tissues with 3 different levels of heterogeneity in the conduction and stimulation pattern to model the inhomogeneous wave propagation observed during atrial fibrillation. Four measures are used to characterize the properties of the simulated electrogram arrays of different electrode sizes. The results show that increasing the electrode size increases the error in LAT estimation and decreases the length of conduction block lines. Moreover, visual inspection also shows that the activation maps generated by larger electrodes are more homogeneous with a lower number of observed wavelets. The increase in electrode size also increases the low voltage areas in the tissue while decreasing the slopes and the number of detected deflections. The effect is more pronounced for a tissue with a higher level of heterogeneity in the conduction pattern. Similar conclusions hold for the measurements performed on clinical data. ConclusionThe electrode size affects the properties of recorded electrogram arrays which can respectively complicate our understanding of atrial fibrillation. This needs to be considered while performing any analysis on the electrograms or comparing the results of different electrogram arrays.

How machine learning is impacting research in atrial fibrillation: implications for risk prediction and future management.

There has been an exponential growth of artificial intelligence (AI) and machine learning (ML) publications aimed at advancing our understanding of atrial fibrillation (AF), which has been mainly driven by the confluence of two factors: the advances in deep neural networks (DeepNNs) and the availability of large, open access databases. It is observed that most of the attention has centred on applying ML for dvsetecting AF, particularly using electrocardiograms (ECGs) as the main data modality. Nearly a third of them used DeepNNs to minimize or eliminate the need for transforming the ECGs to extract features prior to ML modelling; however, we did not observe a significant advantage in following this approach. We also found a fraction of studies using other data modalities, and others centred in aims, such as risk prediction, AF management, and others. From the clinical perspective, AI/ML can help expand the utility of AF detection and risk prediction, especially for patients with additional comorbidities. The use of AI/ML for detection and risk prediction into applications and smart mobile health (mHealth) technology would enable ‘real time’ dynamic assessments. AI/ML could also adapt to treatment changes over time, as well as incident risk factors. Incorporation of a dynamic AI/ML model into mHealth technology would facilitate ‘real time’ assessment of stroke risk, facilitating mitigation of modifiable risk factors (e.g. blood pressure control). Overall, this would lead to an improvement in clinical care for patients with AF.

Understanding the barriers to using oral anticoagulants among long-term aspirin users with atrial fibrillation \u2013 a qualitative study

BackgroundDespite international treatment guidelines currently advocating oral anticoagulants (OACs) as the only appropriate stroke prevention therapy for patients with atrial fibrillation (AF) and evidence that OACs can greatly reduce the risk of stroke with similar risk of bleeding compared with aspirin, the underuse of OACs in patients with AF is common globally, especially in Asia. This study aimed to identify the barriers to prescribing and using OACs among long-term aspirin users with AF.MethodFace-to-face interviews were conducted with fourteen eligible patients with AF using a semi-structured interview guide. The interview recordings were transcribed verbatim and data was analyzed according to the principles of thematic analysis.ResultsFive themes were developed: awareness of AF symptoms and diagnosis; knowledge and understanding of AF and stroke prevention therapy; role of decision-making in prescribing; willingness to switch from aspirin to OACs; and impact of OAC regimen on daily living. The majority of the patients were not aware of the symptoms and diagnosis of AF and only had a vague understanding of the illness and stroke prevention therapy, leading to their minimal involvement in decisions relating to their treatment. Some patients and their caregivers were particularly concerned about the bleeding complications from OACs and perceived aspirin to be a suitable alternative as they find the adverse effects from aspirin manageable and so preferred to remain on aspirin if switching to OACs was not compulsory. Lastly, the lifestyle modifications required when using warfarin, e.g. alternative dosing regimen, diet restriction, were seen as barriers to some patients and caregivers.ConclusionThe findings revealed patients’ knowledge gap in AF management which may be targeted using educational interventions to improve patients’ understanding of AF and its management and hence encourage active participation in the decision-making of their treatment in the future.

Treatment of atrial fibrillation: a comprehensive review and practice guide.

Atrial fibrillation (AF) is an ectopic rhythm originating in the atrium. AF is the most common sustained cardiac arrhythmia in clinical practice and it is an enormous burden worldwide because of the high rates of morbidity, disability and mortality. Treatment of AF has become a hot spot in the field of cardiovascular medicine. Recently, increasing evidence and advancements in medical technology have helped us gain a better understanding of AF. As a result, management of AF has evolved in the past few years, so that we can better prevent and control AF. Current therapy for AF mainly includes drug therapy, catheter ablation, cryoballoon ablation, left atrial appendage closure and the maze procedure. The goal of this article is to update current treatment options for AF. We hope that this article will help deliver good care to AF patients based on the current state-of-the-art evidence.

Animal Models of Atrial Fibrillation.

Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in humans and is a significant source of morbidity and mortality. Despite its prevalence, our mechanistic understanding is incomplete, the therapeutic options have limited efficacy, and are often fraught with risks. A better biological understanding of AF is needed to spearhead novel therapeutic avenues. Although "natural" AF is nearly nonexistent in most species, animal models have contributed significantly to our understanding of AF and some therapeutic options. However, the impediments of animal models are also apparent and stem largely from the differences in basic physiology as well as the complexities underlying human AF; these preclude the creation of a "perfect" animal model and have obviated the translation of animal findings. Herein, we review the vast array of AF models available, spanning the mouse heart (weighing 1/1000th of a human heart) to the horse heart (10× heavier than the human heart). We attempt to highlight the features of each model that bring value to our understanding of AF but also the shortcomings and pitfalls. Finally, we borrowed the concept of a SWOT analysis from the business community (which stands for strengths, weaknesses, opportunities, and threats) and applied this introspective type of analysis to animal models for AF. We identify unmet needs and stress that is in the context of rapidly advancing technologies, these present opportunities for the future use of animal models.

Segmentation and visualization of left atrium through a unified deep learning framework.

Left atrium segmentation and visualization serve as a fundamental and crucial role in clinical analysis and understanding of atrial fibrillation. However, most of the existing methods are directly transmitting information, which may cause redundant information to be passed to affect segmentation performance. Moreover, they did not further consider atrial visualization after segmentation, which leads to a lack of understanding of the essential atrial anatomy. We propose a novel unified deep learning framework for left atrium segmentation and visualization simultaneously. At first, a novel dual-path module is used to enhance the expressiveness of cardiac image representation. Then a multi-scale context-aware module is designed to effectively handle complex appearance and shape variations of the left atrium and associated pulmonary veins. The generated multi-scale features are feed to gated bidirectional message passing module to remove irrelevant information and extract discriminative features. Finally, the features after message passing are efficiently combined via a deep supervision mechanism to produce the final segmentation result and reconstruct 3D volumes. Our approach primarily against the 2018 left atrium segmentation challenge dataset, which consists of 100 3D gadolinium-enhanced magnetic resonance images. Our method achieves an average dice of 0.936 in segmenting the left atrium via fivefold cross-validation, which outperforms state-of-the-art methods. The performance demonstrates the effectiveness and advantages of our network for the left atrium segmentation and visualization. Therefore, our proposed network could potentially improve the clinical diagnosis and treatment of atrial fibrillation.

Mapping of atrial fibrillation: strategies to understand an enigmatic arrhythmia.

The three-dimensional (3D) mapping of cardiac arrhythmias has evolved in recent years to an important and extremely useful tool, providing important insights into arrhythmia mechanisms and thus improving ablation success rates, especially in complex arrhythmias. In atrial fibrillation (AF), the most common but also one of the most complex cardiac arrhythmias, progress in mapping technology has been focusing on several aspects according to the type of AF.In paroxysmal AF, important progress in the exact anatomic reconstruction of the main ablation target, i.e., the pulmonary veins (PV), has been achieved. Perhaps even more importantly, new insights into conduction patterns, such as deceleration at the PV ostia, spiral conduction more distally into the PV, and PV cross-talk have been detected and enable faster and more sustainable PV isolation.In persistent AF, the basic understanding of ongoing AF is perhaps the electrophysiological challenge of the 21st century. Since AF is instable in its course, mapping tools that assess statistically returning patterns or deal with so-called AF "rotors" or "drivers" have been developed, offering unique insights into possible AF mechanisms. Refined high-density bi-atrial voltage maps make it possible to further characterize the arrhythmogenic substrate and scar zones, while new and innovative mapping algorithms enable automated, fast, and reliable annotation of up to thousands of electrograms.This improved understanding of AF mechanisms has led to the development of promising new ablation strategies, some of which are already in use in clinical routine.

NOVEL PROGNOSTIC BIOMARKERS FOR ISCHEMIC STROKE IN PATIENTS WITH ATRIAL FIBRILLATION USING MULTIMARKER SCREENING: INSIGHTS FROM THE ARISTOTLE TRIAL

Biomarkers provide important prognostic information in atrial fibrillation (AF). To further improve the prognostication and understanding of AF we explored a multiplex analytical technic which allow for mass screening of proteins using only small amounts of plasma. In an unstratified case-control

Patients' experiences of atrial fibrillation and non-vitamin K antagonist oral anticoagulants (NOACs), and their educational needs: A qualitative study

PurposeQualitative research on atrial fibrillation (AF) patient's experiences and perceptions of taking the non-vitamin K antagonist oral anticoagulants (NOACs) for stroke prevention is limited. This study explores patients' experiences of dabigatran and their recommendations for development of educational materials. Patients and methodsSemi-structured individual interviews with 8 warfarin-naive and 8 warfarin-experienced AF patients, using qualitative deductive thematic analysis. ResultsThe four main overarching themes included: understanding the diagnosis; reaching a treatment decision; challenges of living with OAC; and patient perceptions of treatment. Patients discussed their shock of diagnosis, and seeking information and support at that time. Narratives suggest patients preferred to be led by the doctor when making treatment decisions, and would often compare dabigatran to warfarin. Patients reported side-effects and challenges with both treatment options, and discussed their beliefs surrounding medications, including misconceptions. In addition to the original framework, two further themes were added: challenges of living with AF, and patient recommendations. Generally patients found AF symptoms distressing, which impacted their quality of life. Patient recommendations included the content and delivery of educational materials and development of tools to help with their understanding of AF and anticoagulation, as well as treatment adherence and anxiety surrounding symptoms and side effects. ConclusionPatient recommendations emphasised the need for interventions to relieve anxiety surrounding the diagnosis and possible treatment side effects. Tailored ‘disease-specific’ support is essential to ensure efficacious treatment. This qualitative study highlights the need for patient involvement in the development of educational materials and resources for patients commencing treatment with NOACs.

Innovative technologies for the cardiac patient and their effects

Writing in the prestigious American journal Science some half a century ago, Norman Holter described a vision where he saw clinicians being able to make ‘long, continuous recordings of physiological phenomena’ from patients ‘with numerous little boxes piling up information about body function’. He predicted ‘full freedom, through elimination of wires, electronic baggage and radio interference’ (Holter, 1961). Well, his vision is now reality. The technology for ambulatory ECG recording, a technique originally introduced by Holter and used for the first time in a clinical setting in 1954 (Maclnnis, 1954), has altered remarkably in the last few years, although you might be hard pushed to notice this in many hospital departments. Signage directing patients to the ‘Tapes Department’ and patient letters requesting their attendance for fitting of a ‘24-hour tape’ are commonplace even though tapes disappeared from most centres over a decade ago. Ambulatory ECG recorders are frequently requested for a traditional 24-hour or 48-hour period even though the pick-up rate in certain circumstances may be low (Kinlay et al, 1996) and modern digital recorders are actually capable of so much more. Patient-activated recorders are issued with variable, but often limited success (Zimetbaum and Josephson, 1998). Following a flurry of developments, a multitude of new recording devices have appeared. Over recent times, I’ve been contacted by the inventor of a ball-shaped ECG recording device that apparently offers great potential as it is ‘easy to hold’ and I’ve been invited to inspect a finger ‘glove’ that detects heart rhythm, blood pressure, oxygen saturation and temperature. A quick search of the web throws up all sorts, ranging from an ‘AF stick’ (Tieleman et al, 2014) to a multi-sensing sticking plaster (Hernandez-Silveira et al, 2015). As described in a previous edition of this journal, mobile phones can easily be adapted to detect the owner’s ECG (Richley and Graham, 2015) and the latest versions of computer-game consoles can remotely monitor pulse rates while a user is playing. In fact, if you’re thinking of dabbling in the heart monitoring industry, it is probably too late to make your fortune, at least in terms of hardware. With this rapid explosion of interest, the effectiveness of these new tools in the clinical setting has yet to be firmly established, though the early signs are encouraging. The detection of paroxysmal atrial fibrillation is one area of particular interest (Turakhia et al, 2015). Ambulatory ECG recording is often performed in patients with a history of cryptogenic stroke with the aim of documenting the presence of atrial fibrillation. In these situations, recording over a period of 30 days or longer has benefits and long-term, continuous recording using unobtrusive, noninvasive devices has potential. Our understanding of atrial fibrillation might well be transformed by these novel recording devices. The true prevalence of atrial fibrillation might be very different to current thinking based on the low-yield techniques used in previous epidemiological studies. It is inevitable that these innovations will disrupt life as we know it in cardiac diagnostic departments. Adhesive patch-based recorders will be more acceptable to patients than numerous electrodes and wires; waterproof products avoid shower dilemmas; disposable units negate infection control issues. The ability of novel devices to link up with mobile phones allows for real-time tracking of the ECG with potential for instant notification of rhythm disturbances. We’re likely to see more monitoring centres popping up, some will be within the current services but perhaps more will be outside of the traditional hospital setting. The ubiquitous, ever-present mobile phone is sure to be key to the future of ambulatory ECG, whether recording directly or acting as a routing device to transmit signals elsewhere for analysis. We might see a shifting of resources from health service-provided kit to patients providing their own devices. Patient choice will be improved in terms of whom they would like to interpret their recordings and from whom they seek their clinical advice. There might even be an improvement in arrhythmia detection rates as patients will inevitably have their phones at hand, rather than languishing in a drawer as is likely to be the case for many of the patient-activated recorders issued today. BJCN

Can oral anticoagulants be stopped safely after a successful atrial fibrillation ablation?

Ablations of atrial fibrillation (AF) have become more widely performed, and the strategy about long-term usage of oral anticoagulants (OACs) after catheter ablation is an important issue, especially for patients without obvious evidences of recurrences. The annual rate of thromboembolic (TE) event after catheter ablation was less than 1%. CHADS2 and CHA2DS2-VASc scores could be used to identify patients at the risk of TE events after ablations who should continue OACs regardless of the status of recurrence. Despite the improvement in understanding of AF and advancement of technology in catheter ablation, the long-term successful rates of paroxysmal and non-paroxysmal AF are around 50% and 30%, respectively. Patients with a high CHADS2 score are at a high risk of recurrence which could continuously occur after the catheter ablation without reaching a plateau. Among the patients with a CHADS2 score of ≥3, 26.9% of the recurrences happened 2 years post catheter ablation. Compared to the episodes of AF before catheter ablation, the AF episodes after ablation procedures are less symptomatic and shorter in duration. Therefore, it may not be safe to stop OACs for patients with a high risk score since the AF episodes are difficult to be detected after ablation procedures, but remain dangerous. In conclusion, the decision about the long-term strategy of OACs should be based on patients' baseline clinical risk scores, such as CHADS2 and CHA2DS2-VASc scores, rather than the status of recurrence.

The role of rotors in atrial fibrillation.

Despite significant advances in our understanding of atrial fibrillation (AF) mechanisms in the last 15 years, ablation outcomes remain suboptimal. A potential reason is that many ablation techniques focus on anatomic, rather than patient-specific functional targets for ablation. Panoramic contact mapping, incorporating phase analysis, repolarization and conduction dynamics, and oscillations in AF rate, overcomes many prior difficulties with mapping AF. This approach provides evidence that the mechanisms sustaining human AF are deterministic, largely due to stable electrical rotors and focal sources in either atrium. Ablation of such sources (Focal Impulse and Rotor Modulation: FIRM ablation) has been shown to improve ablation outcome compared with conventional ablation alone; independent laboratories directly targeting stable rotors have shown similar results. Clinical trials examining the role of stand-alone FIRM ablation are in progress. Looking forward, translating insights from patient-specific mapping to evidence-based guidelines and clinical practice is the next challenge in improving patient outcomes in AF management.

Atrial fibrillation: effects beyond the atrium?

Atrial fibrillation (AF) is the most common sustained clinical arrhythmia and is associated with significant morbidity, mostly secondary to heart failure and stroke, and an estimated two-fold increase in premature death. Efforts to increase our understanding of AF and its complications have focused on unravelling the mechanisms of electrical and structural remodelling of the atrial myocardium. Yet, it is increasingly recognized that AF is more than an atrial disease, being associated with systemic inflammation, endothelial dysfunction, and adverse effects on the structure and function of the left ventricular myocardium that may be prognostically important. Here, we review the molecular and in vivo evidence that underpins current knowledge regarding the effects of human or experimental AF on the ventricular myocardium. Potential mechanisms are explored including diffuse ventricular fibrosis, focal myocardial scarring, and impaired myocardial perfusion and perfusion reserve. The complex relationship between AF, systemic inflammation, as well as endothelial/microvascular dysfunction and the effects of AF on ventricular calcium handling and oxidative stress are also addressed. Finally, consideration is given to the clinical implications of these observations and concepts, with particular reference to rate vs. rhythm control.