Search

Atrial fibrillation (AF) is the most prevalent sustained cardiac arrhythmia. Comprehensive modification of established AF risk factors combined with dietary interventions and breaking deleterious habits has been shown to reduce AF burden and recurrence. Numerous AF risk factors, such as diabetes, obesity or hypertension can be partially related to dietary and lifestyle choices. Therefore, dietary interventions may have potential as a therapeutic approach in AF. Based on available data, current guidelines recommend alcohol abstinence or reduction to decrease AF symptoms, burden, and progression, and do not indicate the need for caffeine abstention to prevent AF episodes (unless it is a trigger for AF symptoms). Uncertainty persists regarding harms or benefits of other dietary factors including chocolate, fish, salt, polyunsaturated and monounsaturated fatty acids, vitamins, and micronutrients. This article provides a systematic review of the association between AF and both dietary patterns and components. Additionally, it discusses potentially related mechanisms and introduces different strategies to assess patients' nutrition patterns, including mobile health solutions and diet indices. Finally, it highlights the gaps in knowledge requiring future investigation. [ABSTRACT FROM AUTHOR]

Background and Aims Atrial fibrillation (AF) is a chronic progressive disorder. Persistent forms of AF are associated with increased rates of thromboembolism, heart failure, and death. Catheter ablation modifies the pathogenic mechanism of AF progression. No randomized studies have evaluated the impact of the ablation energy on progression to persistent atrial tachyarrhythmia. Methods Three hundred forty-six patients with drug-refractory paroxysmal AF were enrolled and randomly assigned to contact-force–guided RF ablation (CF-RF ablation, 115), 4 min cryoballoon ablation (CRYO-4, 115), or 2 min cryoballoon ablation (CRYO-2, 116). Implantable cardiac monitors placed at study entry were used for follow-up. The main outcome was the first episode of persistent atrial tachyarrhythmia. Secondary outcomes included atrial tachyarrhythmia recurrence and arrhythmia burden on the implantable monitor. Results At a median of 944.0 (interquartile range [IQR], 612.5–1104) days, 0 of 115 patients (0.0%) randomly assigned to CF-RF, 8 of 115 patients (7.0%) assigned to CRYO-4, and 5 of 116 patients (4.3%) assigned to CRYO-2 experienced an episode of persistent atrial tachyarrhythmia (P =.03). A documented recurrence of any atrial tachyarrhythmia ≥30 s occurred in 56.5%, 53.9%, and 62.9% of those randomized to CF-RF, CRYO-4, and CRYO-2, respectively; P =.65. Compared with that of the pre-ablation monitoring period, AF burden was reduced by a median of 99.5% (IQR 94.0%, 100.0%) with CF-RF, 99.9% (IQR 93.3%–100.0%) with CRYO-4, and 99.1%% (IQR 87.0%–100.0%) with CRYO-2 (P =.38). Conclusions Catheter ablation of paroxysmal AF using radiofrequency energy was associated with fewer patients developing persistent AF on follow-up. [ABSTRACT FROM AUTHOR]

Key Points: Question: Does atrial fibrillation catheter ablation have an impact on mental health? Findings: In this randomized clinical trial of 100 patients with symptomatic atrial fibrillation, catheter ablation with reduction in arrhythmia burden and antiarrhythmic drug use was associated with improvement in markers of psychological distress compared with medical therapy alone. Meaning: Improvement of severe psychological distress may be an additional benefit of catheter ablation treatment for atrial fibrillation. Importance: The impact of atrial fibrillation (AF) catheter ablation on mental health outcomes is not well understood. Objective: To determine whether AF catheter ablation is associated with greater improvements in markers of psychological distress compared with medical therapy alone. Design, Setting, and Participants: The Randomized Evaluation of the Impact of Catheter Ablation on Psychological Distress in Atrial Fibrillation (REMEDIAL) study was a randomized trial of symptomatic participants conducted in 2 AF centers in Australia between June 2018 and March 2021. Interventions: Participants were randomized to receive AF catheter ablation (n = 52) or medical therapy (n = 48). Main Outcomes and Measures: The primary outcome was Hospital Anxiety and Depression Scale (HADS) score at 12 months. Secondary outcomes included follow-up assessments of prevalence of severe psychological distress (HADS score >15), anxiety HADS score, depression HADS score, and Beck Depression Inventory-II (BDI-II) score. Arrhythmia recurrence and AF burden data were also analyzed. Results: A total of 100 participants were randomized (mean age, 59 [12] years; 31 [32%] women; 54% with paroxysmal AF). Successful pulmonary vein isolation was achieved in all participants in the ablation group. The combined HADS score was lower in the ablation group vs the medical group at 6 months (8.2 [5.4] vs 11.9 [7.2]; P =.006) and at 12 months (7.6 [5.3] vs 11.8 [8.6]; between-group difference, −4.17 [95% CI, −7.04 to −1.31]; P =.005). Similarly, the prevalence of severe psychological distress was lower in the ablation group vs the medical therapy group at 6 months (14.2% vs 34%; P =.02) and at 12 months (10.2% vs 31.9%; P =.01), as was the anxiety HADS score at 6 months (4.7 [3.2] vs 6.4 [3.9]; P =.02) and 12 months (4.5 [3.3] vs 6.6 [4.8]; P =.02); the depression HADS score at 3 months (3.7 [2.6] vs 5.2 [4.0]; P =.047), 6 months (3.4 [2.7] vs 5.5 [3.9]; P =.004), and 12 months (3.1 [2.6] vs 5.2 [3.9]; P =.004); and the BDI-II score at 6 months (7.2 [6.1] vs 11.5 [9.0]; P =.01) and 12 months (6.6 [7.2] vs 10.9 [8.2]; P =.01). The median (IQR) AF burden in the ablation group was lower than in the medical therapy group (0% [0%-3.22%] vs 15.5% [1.0%-45.9%]; P <.001). Conclusion and Relevance: In this trial of participants with symptomatic AF, improvement in psychological symptoms of anxiety and depression was observed with catheter ablation, but not medical therapy. Trial Registration: ANZCTR Identifier: ACTRN12618000062224 This randomized clinical trial evaluates the prevalence of psychological distress in participants referred for atrial fibrillation treatment. [ABSTRACT FROM AUTHOR]

Introduction: Use of a novel magnetic sensor enabled optical contact force ablation catheter has been established to be safe and effective for treatment of symptomatic drug‐refractory paroxysmal atrial fibrillation (AF) but has yet to be demonstrated in the persistent AF (PersAF) population. Methods: PERSIST‐END was a multicenter, prospective, nonrandomized, investigational study designed to demonstrate the safety and effectiveness of TactiCath™ Ablation Catheter, Sensor Enabled™(SE) (TactiCath SE) for use in the treatment of subjects with documented PersAF refractory or intolerant to at least one Class I/III AAD. The ablation strategy included pulmonary vein isolation and additional targets at physician discretion. Follow‐up through 15‐months, including a 3‐month blanking period and 3‐month therapy consolidation period, was performed with cardiac event and Holter monitoring. Primary safety, primary effectiveness, clinical success, and quality of life (QOL) endpoints were analyzed. Results: Of 224 subjects enrolled at 21 investigational sites in the United States and Australia, 223 underwent ablation with the investigational catheter. The primary safety event rate was 3.1% (seven events in seven subjects). The Kaplan–Meier estimate of freedom from AF/atrial flutter/atrial tachycardia recurrence at 15‐months was 61.6% and clinical success at 15 months was 89.8%. Subject QOL significantly improved following ablation as assessed via AFEQT (31.6 point increase, p <.0001) and EQ‐5D‐5L (10.7 point increase, p <.0001) and was met with a 53% reduction in all cause cardiovascular healthcare utilization. Conclusion: The sensor‐enabled force‐sensing catheter is safe and effective for the treatment of drug refractory recurrent symptomatic PersAF, reducing arrhythmia recurrence while improving QOL and healthcare utilization. [ABSTRACT FROM AUTHOR]

Background: Patient-reported outcome measures are important in person-centered care, providing valuable information about patients' experiences. Disease-specific questionnaires add important information about a certain disease in comparison to generic questionnaires. Questionnaires need to be validated in the targeted population to achieve reliable data. The purpose with the study was to use Rasch measurement theory to evaluate the English version of the ASTA questionnaire. Methods: The Rasch model theory was used to evaluate global and item fit, targeting, response category functioning, local independency, unidimensionality, differential item functioning (DIF) for gender and age, and reliability. Results: The study included 202 patients undergoing DC conversion or catheter ablation at the Centre for Heart Rhythm Disorders at the University of Adelaide, Australia. The mean age was 67 years and 30% were women. Most patients had atrial fibrillation (n = 179), others had atrial flutter or had a combination. One of nine items demonstrated unsatisfactory model fit in the ASTA Symptom scale and two of 13 in the ASTA Health-Related Quality of Life (HRQoL) scale. Unidimensionality was supported for both scales. The targeting was acceptable except for the lower end of the scales. Both scales showed reversed thresholds for the response categories "quite a lot" and "a lot" (eight of ASTA symptoms and 12 of ASTA HRQoL items). Some problems with local dependency were detected in both scales. The reliability (person separation index) was satisfactory: 0.75 for the ASTA symptom scale and 0.77 for the ASTA HRQoL scale. No DIF for gender and age were detected. Conclusions: The English version of the ASTA questionnaire demonstrated satisfactory measurement properties according to the Rasch model. However, it needs to be evaluated in patients with other arrhythmias. The response categories should be considered as well as DIF in further validation. The ASTA questionnaire can be used for assessments of symptoms and HRQoL between groups of different ages and genders in patients with arrhythmia. [ABSTRACT FROM AUTHOR]

Recent preclinical and observational cohort studies have implicated imbalances in gut microbiota composition as a contributor to atrial fibrillation (AF). The gut microbiota is a complex and dynamic ecosystem containing trillions of microorganisms, which produces bioactive metabolites influencing host health and disease development. In addition to host-specific determinants, lifestyle-related factors such as diet and drugs are important determinants of the gut microbiota composition. In this review, we discuss the evidence suggesting a potential bidirectional association between AF and gut microbiota, identifying gut microbiota-derived metabolites as possible regulators of the AF substrate. We summarize the effect of gut microbiota on the development and progression of AF risk factors, including heart failure, hypertension, obesity, and coronary artery disease. We also discuss the potential anti-arrhythmic effects of pharmacological and diet-induced modifications of gut microbiota composition, which may modulate and prevent the progression to AF. Finally, we highlight important gaps in knowledge and areas requiring future investigation. Although data supporting a direct relationship between gut microbiota and AF are very limited at the present time, emerging preclinical and clinical research dealing with mechanistic interactions between gut microbiota and AF is important as it may lead to new insights into AF pathophysiology and the discovery of novel therapeutic targets for AF. [ABSTRACT FROM AUTHOR]

Management of atrial fibrillation (AF) requires a comprehensive approach due to the limited success of medical or procedural approaches in isolation. Multiple modifiable risk factors contribute to the development and progression of the underlying substrate, with a heightened risk of progression evident with inadequate risk factor management. With increased mortality, stroke, heart failure and healthcare utilisation linked to AF, international guidelines now strongly support risk factor modification as a critical pillar of AF care due to evidence demonstrating the efficacy of this approach. Effective lifestyle management is key to arrest and reverse the progression of AF, in addition to increasing the likelihood of freedom from arrhythmia following catheter ablation. [ABSTRACT FROM AUTHOR]

This editorial refers to 'Cannabis, cocaine, methamphetamine, and opiates increase the risk of incident atrial fibrillation', by A.L. Lin I et al i . https://doi.org/10.1093/eurheartj/ehac558. The optimal management of patients with drug use and the long-term effects of these substances on the heart and AF recurrences are still unclear. It is important for future research to examine and understand the impact of drugs on AF, particularly in the light of drug policy reform and legalisation. Questions remain as to what dose of drug would promote AF onset and how much AF would result from an isolated exposure. [Extracted from the article]

Dietary intake has been shown to change the composition of gut microbiota and some changes in microbiota (dysbiosis) have been linked to diabetes, hypertension, and obesity, which are established risk factors for atrial fibrillation (AF). In addition, intestinal dysbiosis generates microbiota-derived bioactive metabolites that might exert proarrhythmic actions. Although emerging preclinical investigations and clinical observational cohort studies suggest a possible role of gut dysbiosis in AF promotion, the exact mechanisms through which dysbiosis contributes to AF remain unclear. This Viewpoint article briefly reviews evidence suggesting that abnormalities in the intestinal microbiota play an important and little-recognized role in the pathophysiology of AF and that an improved understanding of this role may open up new possibilities in the management of AF. [ABSTRACT FROM AUTHOR]

Aims Obesity, an established risk factor of atrial fibrillation (AF), is frequently associated with enhanced inflammatory response. However, whether inflammatory signaling is causally linked to AF pathogenesis in obesity remains elusive. We recently demonstrated that the constitutive activation of the 'NACHT, LRR, and PYD Domains-containing Protein 3' (NLRP3) inflammasome promotes AF susceptibility. In this study, we hypothesized that the NLRP3 inflammasome is a key driver of obesity-induced AF. Methods and results Western blotting was performed to determine the level of NLRP3 inflammasome activation in atrial tissues of obese patients, sheep, and diet-induced obese (DIO) mice. The increased body weight in patients, sheep, and mice was associated with enhanced NLRP3-inflammasome activation. To determine whether NLRP3 contributes to the obesity-induced atrial arrhythmogenesis, wild-type (WT) and NLRP3 homozygous knockout (NLRP3−/−) mice were subjected to high-fat-diet (HFD) or normal chow (NC) for 10 weeks. Relative to NC-fed WT mice, HFD-fed WT mice were more susceptible to pacing-induced AF with longer AF duration. In contrast, HFD-fed NLRP3−/− mice were resistant to pacing-induced AF. Optical mapping in DIO mice revealed an arrhythmogenic substrate characterized by abbreviated refractoriness and action potential duration (APD), two key determinants of reentry-promoting electrical remodeling. Upregulation of ultra-rapid delayed-rectifier K+-channel (Kv1.5) contributed to the shortening of atrial refractoriness. Increased profibrotic signaling and fibrosis along with abnormal Ca2+ release from sarcoplasmic reticulum (SR) accompanied atrial arrhythmogenesis in DIO mice. Conversely, genetic ablation of Nlrp3 (NLRP3−/−) in HFD-fed mice prevented the increases in Kv1.5 and the evolution of electrical remodeling, the upregulation of profibrotic genes, and abnormal SR Ca2+ release in DIO mice. Conclusion These results demonstrate that the atrial NLRP3 inflammasome is a key driver of obesity-induced atrial arrhythmogenesis and establishes a mechanistic link between obesity-induced AF and NLRP3-inflammasome activation. [ABSTRACT FROM AUTHOR]

Summary of the progress in arrhythmias in 2020. RACE4 and ALL-IN indicated that integrated nurse-led care improves outcomes in AF patients. 3,4 The same was reported for early rhythm control therapy 15 and cryoablation as initial AF treatment. 25,26 Subcutaneous ICD was non-inferior to classical transvenous ICD therapy in PRAETORIAN. 54 One mechanistic study showed that autoantibodies against misexpressed actin, keratin, and connexin-43 proteins create a blood-borne biomarker profile enhancing diagnosis of Brugada syndrome. 50 Another mechanistic study indicated that transseptal LV pacing yields similar improvement in contractility as His bundle pacing whilst being more easy to execute. 44 In PRE-DETERMINE a simple-to-use ECG risk score improved risk prediction in patients with ischemic heart disease possibly enhancing appropriate ICD therapy in high risk patients. 58 [ABSTRACT FROM AUTHOR]

While isolation of the pulmonary veins is firmly established as effective treatment for the majority of paroxysmal atrial fibrillation (AF) patients, there is recognition that patients with persistent AF have substrate for perpetuation of arrhythmia existing outside of the pulmonary veins. Various computational approaches have been used to identify targets for effective ablation of persistent AF. This paper aims to discuss the clinical aspects of computational approaches that aim to identify critical sites for treatment. Various analyses of electrogram characteristics have been performed with this aim. Leading techniques for electrogram analysis are Complex Fractionated Atrial Electrograms (CFAE) and Dominant Frequency (DF). These techniques have been the subject of clinical trials of which the results are discussed. Evaluation of the activation patterns of atria in AF has been another avenue of research. Focal Impulse and Rotor Modulation (FIRM) mapping and forms of Body Surface Mapping aim to characterize multiple atrial wavelets, macro-reentry and focal sources which have been proposed as basic mechanisms perpetuating AF. Both invasive and non-invasive activation mapping techniques are reviewed. The presence of atrial fibrosis causes non-uniform anisotropic impulse propagation. Therefore, identification of fibrosis by imaging techniques is an avenue of potential research. The leading contender for imaging-based techniques is Cardiac Magnetic Resonance (CMR). As this technology advances, improvements in resolution and scar identification have positioned CMR as the mode of choice for analysis of atrial structure. AF has been demonstrated to be associated with obesity, inactivity and diseases of modern life. An opportunity exists for detailed computational analysis of the impact of risk factor modification on atrial substrate. This ranges from microstructural investigation through to examination at a population level via registries and public health interventions. Computational analysis of atrial substrate has moved from basic science toward clinical application. Future directions and potential limitations of such analyses are examined in this review. [ABSTRACT FROM AUTHOR]

Aims: Rotor mapping and ablation have gained favour over the recent years as an emerging ablation strategy targeting drivers of atrial fibrillation (AF). Their efficacy, however, has been a topic of great debate with variable outcomes across centres. The aim of this study was to systematically review the recent medical literature to determine the medium-term outcomes of rotor ablation in patients with paroxysmal atrial fibrillation (PAF) and persistent atrial fibrillation (PeAF).Methods and results: A systematic search of the contemporary scientific literature (PubMed and EMBASE) was performed in August 2017. Only studies assessing arrhythmia-free survival from rotor ablation of AF were included. We used the random-effects model to assess the primary outcome of pooled medium-term single-procedure AF-free survival for both PAF and PeAF. Success rates from multiple procedures and complication rates were also examined. We included 11 observational studies (4 PAF and 10 PeAF) with a total of 556 patients (166 PAF and 390 PeAF). Pooled single-procedure freedom from AF was 37.8% [95% confidence interval 5.6-86.3%] at a mean follow-up period of 13.8 ± 1.8 months for PAF and 59.2% (95% CI 41.4-74.9%) at a mean follow-up period of 12.9 ± 6 months for PeAF. There was a marked heterogeneity between studies (I2 = 93.8% for PAF and 88.3% for PeAF). The mean complication rate of rotor ablation among the reported studies was 3.4%.Conclusion: The wide variability in success rate between different centres performing rotor ablations suggests that the optimal ablation strategy, particularly targeting rotors, is unclear. Results from randomized studies are necessary before this technique can be considered as an established clinical tool. [ABSTRACT FROM AUTHOR]

The cardiovascular benefits of regular exercise have been well described, including a significant reduction in cardiovascular morbidity and mortality for those meeting recommended guidelines. Yet the impact of physical activity on the incidence of atrial fibrillation (AF) has been less clear. This review seeks to define the optimal dose and duration for the prevention and treatment of AF. In doing so, we review the evidence that supports a decline in AF risk for those who achieve a weekly physical activity dose slightly above the current recommended guidelines. Furthermore, we identify the reduced AF incidence in those individuals who attain a cardiorespiratory fitness of 8 METs (metabolic equivalents of task) or more during maximal exercise testing. Finally, we review the evidence that shows an excess of AF among regular participants of endurance exercise. [ABSTRACT FROM AUTHOR]

Catheter ablation is now at the forefront of the management of symptomatic atrial fibrillation (AF). Its role in paroxysmal AF is well defined with considerable data supporting its role. Catheter ablation in persistent AF has been less effective and the subject of considerable debate. Mechanistic studies have demonstrated the critical role of pulmonary vein physiology in paroxysmal AF, whereas the mechanisms that sustain persistent AF are not well understood. Additional substrate ablation in persistent AF has not improved long-term outcomes and the use of novel mapping technologies to assess rotor activity remains controversial. This review will focus on the current understanding of the mechanistic basis of paroxysmal and persistent AF, the role of catheter ablation and, recent advances in the management of these complex arrhythmias. [ABSTRACT FROM AUTHOR]

Background: Early studies demonstrated relatively low success rates for pulmonary vein isolation (PVI) alone in patients with persistent atrial fibrillation (PeAF). However, the advent of new technologies and the observation that additional substrate ablation does not improve outcomes have created a new focus on PVI alone for treatment of PeAF.Objective: The purpose of this study was to systematically review the recent medical literature to determine current medium-term outcomes when a PVI-only approach is used for PeAF.Methods: An electronic database search (MEDLINE, Embase, Web of Science, PubMed, Cochrane) was performed in August 2016. Only studies of PeAF patients undergoing a "PVI only" ablation strategy using contemporary radiofrequency (RF) technology or second-generation cryoballoon (CB2) were included. A random-effects model was used to assess the primary outcome of pooled single-procedure 12-month arrhythmia-free survival. Predictors of recurrence were also examined and a meta-analysis performed if ≥4 studies examined the parameter.Results: Fourteen studies of 956 patients, of whom 45.2% underwent PVI only with RF and 54.8% with CB2, were included. Pooled single-procedure 12-month arrhythmia-free survival was 66.7% (95% confidence interval [CI] 60.8%-72.2%), with the majority of patients (80.5%) off antiarrhythmic drugs. Complication rates were very low, with cardiac tamponade occurring in 5 patients (0.6%) and persistent phrenic nerve palsy in 5 CB2 patients (0.9% of CB2). Blanking period recurrence (hazard ratio 4.68, 95% CI 1.70-12.9) was the only significant predictor of recurrence.Conclusion: A PVI-only strategy in PeAF patients with a low prevalence of structural heart disease using contemporary technology yields excellent outcomes comparable to those for paroxysmal AF ablation. [ABSTRACT FROM AUTHOR]

Introduction: Recent research has unravelled an increasing list of cardiac conditions and risk factors that may be responsible for the abnormal underlying atrial substrate that predisposes to atrial fibrillation (AF). Atrial fibrosis has been demonstrated as the pivotal structural abnormality underpinning conduction disturbances that promote AF in different disease models. Despite the advancement in our discoveries of the molecular mechanisms involved in the profibrotic milieu, targeted therapeutics against atrial fibrosis remain lacking. Areas covered: This review is focused on detailing the key molecular signalling pathways that contribute to atrial fibrosis including: angiotensin II, transforming growth factor (TGF- ß1), connective tissue growth factor (CTGF) and endothelin-1. We also discussed the potential therapeutic options that may be useful in modulating the abnormal atrial substrate. In addition, we examined the new paradigm of AF care in lifestyle and risk factor management that has been shown to arrest and reverse the atrial remodelling process leading to improved AF outcomes. Expert commentary: The future of AF care is likely to require an integrated approach consisting of aggressive risk factor management in addition to the established paradigm of rate and rhythm management and anticoagulation. Translational studies on molecular therapeutics to combat atrial fibrosis is urgently needed. [ABSTRACT FROM AUTHOR]

Introduction: Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia with a one in four lifetime risk in adults over the age of forty. Traditionally, AF management has focused on the three pillars of rate control, rhythm control and appropriate anticoagulation to reduce stroke risk. More recently, the importance of cardiovascular risk factor management in AF has emerged as a fourth and essential pillar with improved patient outcomes.Areas Covered: Here, we aim to summarize the current available evidence for the association between various modifiable risk factors and AF, and to identify optimal treatment targets to improve outcomes. Expert Commentary: Care for AF patients utilizing an integrated approach and aggressive lifestyle management may reduce the enormous burden of this arrhythmia. [ABSTRACT FROM AUTHOR]

Atrial fibrillation (AF) is the most common cardiac arrhythmia in humans, with an estimated lifetime prevalence of 25%. It is characterized by irregular and disorganized electrical activation of the atria. In the past decade, catheter ablation, i.e., focally burning targeted areas of cardiac muscle, has emerged as a potentially curative therapy for AF. Accompanying this development there has been an increasing interest in quantitative intraprocedural signal analysis to guide the selection of ablation targets. In this review, we provide an overview of quantitative signal processing approaches for mapping and ablation of AF. [ABSTRACT FROM AUTHOR]

Background: Chronic kidney disease (CKD) patients undergoing hemodialysis (HD) have a high risk of sudden cardiac death (SCD). A unique risk factor may be a longer interval between HD sessions (interdialytic period). Inherent in conventional HD (thrice-weekly) are two 48-hour short breaks (SIDP) and one 72-hour long break (LIDP) between HD sessions.Objective: We used an implantable cardiac monitor (ICM) to define the incidence and timing of significant arrhythmias in an HD population.Methods: Fifty CKD patients undergoing HD with left ventricular ejection fraction >35% had an ICM inserted, with intensive follow-up to record SCD events and predefined bradyarrhythmias and tachyarrhythmias.Results: Mean age of the patients was 67 ± 11 years; 72% were male, and the mean follow-up was 18 ± 4 months. There were 8 unexpected SCDs (16%), all during the LIDP. The terminal event was severe bradycardia with asystole in each recorded case. No episodes of polymorphic ventricular tachycardia (VT) occurred. A total of 7686 arrhythmia events were recorded in 43 patients (86%), including bradycardia in 15 patients (30%), sinus arrest in 14 (28%), second-degree atrioventricular block in 4 (8%), nonsustained VT in 10 (20%), and new-onset paroxysmal atrial fibrillation in 14 (28%). The LIDP was the highest-risk period for all arrhythmias (P < .001). The arrhythmia event rate per hour was greatest during the first pre-HD period of the week compared with any other peri-HD period (P < .001).Conclusion: Risk of SCD and significant arrhythmias is greatest during the LIDP. SCD was attributable to severe bradycardia and asystole. Interventions to prevent this type of SCD or shorten the LIDP deserve further evaluation.Clinical Trial Registration Information: URL: https://www.anzctr.org.au (Unique identifier: ACTRN12613001326785). [ABSTRACT FROM AUTHOR]

Background The Reveal LINQ is a miniaturized insertable cardiac monitor (ICM) with wireless telemetry for remote monitoring of patients with suspected arrhythmias. Objective The primary objective of this study was to evaluate the functionality of the Reveal LINQ system by measuring R-wave sensing and data transmission. Methods The Reveal LINQ Usability Study was a nonrandomized, prospective, multicenter trial. The study enrolled 30 patients with any indication for an ICM. Data were collected at baseline, implantation, and 1-month follow-up visits and through daily wireless transmissions. Results Thirty patients were enrolled and had a Reveal LINQ device implanted. The mean age was 55 ± 15 years. All patients had successful implantation of the ICM in one of the recommended locations. Ease of implantation procedure was rated as easy or very easy for 90% of implantations. R-wave amplitudes were 0.584 ± 0.325 mV at implantation and 0.596 ± 0.336 mV at 1 month ( P = .8). Automatic transmissions were successful 79.5% (69.5%–86.9%) of the time. Transmission failures that caused a delay in data transfer occurred because of incomplete data reception or patients being out of range in 45% and 42% of instances, respectively. For all patients, transmission failures were followed by successful automated or manual transmission of information on a subsequent day. The devices stored 217 arrhythmic episodes during 30 days of follow-up, identified as atrial fibrillation (n = 111), asystole (n = 95), bradycardia (n = 4), fast ventricular tachycardia (n = 1), and ventricular tachycardia ( n = 6). No serious procedure- or system-related adverse events occurred during the 1-month follow-up period. Conclusion The miniaturized Reveal LINQ ICM supports arrhythmia detection and monitoring, achieving adequate sensing performance without safety issues. Clinical Trial Registration URL: http://www.clinicaltrials.gov . Unique identifier: NCT01965899. [ABSTRACT FROM AUTHOR]

Background: Rotors are postulated to maintain cardiac fibrillation. Despite the importance of bipolar electrograms in clinical electrophysiology, few data exist on the properties of bipolar electrograms at rotor sites. The pivot of a spiral wave is characterized by relative uncertainty of wavefront propagation direction compared to the periphery. The bipolar electrograms used in electrophysiology recording encode information on both direction and timing of approaching wavefronts. Objective: To test the hypothesis that bipolar electrograms from the pivot of rotors have higher Shannon entropy (ShEn) than electrograms recorded at the periphery due to the spatial dynamics of spiral waves. Methods and Results: We studied spiral wave propagation in 2-dimensional sheets constructed using a simple cell automaton (FitzHugh-Nagumo), atrial (Courtemanche-Ramirez-Nattel) and ventricular (Luo-Rudy) myocyte cell models and in a geometric model spiral wave. In each system, bipolar electrogram recordings were simulated, and Shannon entropy maps constructed as a measure of electrogram information content. ShEn was consistently highest in the pivoting region associated with the phase singularity of the spiral wave. This property was consistently preserved across; (i) variation of model system (ii) alterations in bipolar electrode spacing, (iii) alternative bipolar electrode orientation (iv) bipolar electrogram filtering and (v) in the presence of rotor meander. Directional activation plots demonstrated that the origin of high ShEn at the pivot was the directional diversity of wavefront propagation observed in this location. Conclusions: The pivot of the rotor is consistently associated with high Shannon entropy of bipolar electrograms despite differences in action potential model, bipolar electrode spacing, signal filtering and rotor meander. Maximum ShEn is co-located with the pivot for rotors observed in the bipolar electrogram recording mode, and may be an intrinsic property of spiral wave dynamic behaviour. [ABSTRACT FROM AUTHOR]

The article investigates whether bipolar electrogram Shannon entropy (ShEn), a measure of signal amplitude distribution, could differentiate the pivot from surrounding peripheral regions and thereby assist clinical rotor mapping of atrial fibrillation (AF). The study covered bipolar electrogram recordings in computer simulation, isolated rat atria, epicardial recordings of induced AF in sheep and persistent AF patients. Results suggested that ShEn may assist AF rotor mapping.

Various forms of heart disease are associated with remodeling of the heart muscle, which results in a perturbation of cell-to-cell electrical coupling. These perturbations may alter the trajectory of spiral wave drift in the heart muscle. We investigate the effect of spatially extended inhomogeneity of transverse cell coupling on the spiral wave trajectory using a simple active media model. The spiral wave was either attracted or repelled from the center of inhomogeneity as a function of cell excitability and gradient of the cell coupling. High levels of excitability resulted in an attraction of the wave to the center of inhomogeneity, whereas low levels resulted in an escape and termination of the spiral wave. The spiral wave drift velocity was related to the gradient of the coupling and the initial position of the wave. In a diseased heart, a region of altered transverse coupling corresponds with local gap junction remodeling that may be responsible for stabilization-destabilization of spiral waves and hence reflect potentially important targets in the treatment of heart arrhythmias. [ABSTRACT FROM AUTHOR]

Aims There is increasing evidence of the role direction-dependent conduction plays in the arrhythmogenic interaction between ectopic triggers and abnormal atrial substrates. We thus sought to characterize direction-dependent conduction in chronically stretched atria. Methods and results Twenty-four patients with chronic atrial stretch due to mitral stenosis and 24 reference patients with left-sided accessory pathways were studied. Multipolar catheters placed at the lateral right atrium, crista terminalis, and coronary sinus (CS) characterized direction-dependent conduction along linear catheters and across the crista terminalis. Bi-atrial electroanatomic maps were created in both sinus rhythm and an alternative wavefront direction by pacing from the distal CS. This allowed an assessment of conduction velocities, electrogram, and voltage characteristics during wavefronts propagating in different directions. While differing wavefront directions caused changes in both chronic atrial stretch and reference patients (P< 0.001 for all), these direction-dependent changes were greater in chronic atrial stretch compared with reference patients, who exhibited greater slowing in conduction velocities (P= 0.09), prolongation of bi-atrial activation time (P= 0.04), increase in number (P< 0.001) and length (P< 0.001) of lines of conduction block, increase in fractionated electrograms (P< 0.001), and decrease in voltage (P= 0.08) during left-to-right compared with right-to-left atrial activation. These direction-dependent changes were associated with a greater propensity for chronically stretched atria to develop atrial fibrillation (P= 0.02). Conclusions Atrial remodelling in chronic atrial stretch exacerbates physiological direction-dependent conduction characteristics. Our data suggest that the greater direction-dependent conduction seen in patients with chronic atrial stretch may promote arrhythmogenesis due to ectopic triggers from the left atrium. [ABSTRACT FROM PUBLISHER]

Atrial fibrillation (AF) is the most common clinically important cardiac arrhythmia. It is an important cause of stroke, contributes to the burden of heart failure and is a major contributor to health expenditure. Percutaneous catheter ablation is superior to medical therapy in reducing AF recurrences. It has an important role in treatment of patients with failed drug therapy. Successful catheter ablation improves left ventricular function in patients with heart failure. In addition, it may be appropriate for selected highly symptomatic patients as first line therapy. Catheter ablation for AF has been shown in randomised trials to reduce hospital admissions and improve quality of life. There is evidence from registry data to suggest it reduces the risk of stroke and improves mortality. Cost effectiveness has been demonstrated by modelling studies in both Europe and the United States. [ABSTRACT FROM AUTHOR]

Background: There is a known association between obstructive sleep apnea (OSA) and atrial fibrillation (AF); however, how OSA affects the atrial myocardium is not well described. Objective: To determine whether patients with OSA have an abnormal atrial substrate. Methods: Forty patients undergoing ablation of paroxysmal AF and in sinus rhythm (20 with OSA [apnea–hypopnea index ≥ 15] and 20 reference patients with no OSA [apnea–hypopnea index < 15] by polysomnography) were studied. Multipolar catheters were positioned at the lateral right atrium (RA), coronary sinus, crista terminalis, and RA septum to determine the effective refractory period at 5 sites, conduction time along linear catheters at the RA and the coronary sinus, conduction at the crista terminalis, and sinus node function (corrected sinus node recovery time). Biatrial electroanatomic maps were created to determine the voltage, conduction, and distribution of complex electrograms (duration ≥ 50 ms). Results: The groups had no differences in the prevalence of established risk factors for AF. Patients with OSA had the following compared with those without OSA: no difference in effective refractory period (P = .9), prolonged conduction times along the coronary sinus and RA (P = .02), greater number (P = .003) and duration (P = .03) of complex electrograms along the crista terminalis, longer P-wave duration (P = .01), longer corrected sinus node recovery time (P = .02), lower atrial voltage (RA, P <.001; left atrium, P <.001), slower atrial conduction velocity (RA, P = .001; left atrium, P = .02), and more widespread complex electrograms in both atria (RA, P = .02; left atrium, P = .01). Conclusion: OSA is associated with significant atrial remodeling characterized by atrial enlargement, reduction in voltage, site-specific and widespread conduction abnormalities, and longer sinus node recovery. These features may in part explain the association between OSA and AF. [Copyright &y& Elsevier]

Elevated QT interval variability is a predictor of malignant ventricular arrhythmia, but the underlying mechanisms are incompletely understood. A recent study in dogs with pacing-induced heart failure suggests that QT variability is linked to cardiac sympathetic nerve activity. The aim of this study was to determine whether increased cardiac sympathetic activity is associated with increased beat-to-beat QT interval variability in patients with essential hypertension. We recorded resting norepinephrine (NE) spillover into the coronary sinus and single-lead, short-term, high-resolution, body-surface ECG in 23 patients with essential hypertension and 9 normotensive control subjects. To assess beat-to-beat QT interval variability, we calculated the overall QT variability (QTVN) as well as the QT variability index (QTVi). Cardiac NE spillover (12.2 ± 6.5 vs. 20.7 ± 14.7, P = 0.03) and QTVi (-1.75 ± 0.36 vs. -1.42 ± 0.50, P = 0.05) were significantly increased in hypertensive patients compared with normotensive subjects. QTVN was significantly correlated with cardiac NE spillover (r2 = 0.31, P = 0.001), with RR variability (r2 = 0.20, P = 0.008), and with systolic blood pressure (r2 = 0.16, P = 0.02). Linear regression analysis identified the former two as independent predictors of QTVN. In conclusion, elevated repolarization lability is directly associated with sympathetic cardiac activation in patients with essential hypertension. [ABSTRACT FROM AUTHOR]

Background: Hypertension is frequently complicated by the development of atrial fibrillation (AF). However, the mechanisms of this link remain poorly understood. In addition, whether short-term hypertension can result in a substrate for AF is not known. Objective: The purpose of this study was to characterize the atrial substrate predisposing to AF due to short-duration hypertension. Methods: Sixteen sheep were studied: 10 had induced hypertension for 7 ± 4 weeks via the “one-kidney, one-clip” model, and six were controls. Cardiac magnetic resonance imaging was used to assess functional changes. Open-chest electrophysiological study was performed using a custom-made 128-electrode epicardial plaque applied to both right (RA) and left atria (LA), including the Bachmann''s bundle, to determine effective refractory periods (ERPs) and conduction velocity at four pacing cycle lengths from six sites. Tissue specimens were harvested for structural analysis. Results: The hypertensive group demonstrated the following compared with controls: higher blood pressure (P <.0001), enlarged LA (P <.05), reduced LA ejection fraction (P <.05), uniformly higher mean ERP (P <.001), slower mean conduction velocity (P <.001), higher conduction heterogeneity index (P <.0001), greater AF inducibility (P = .03), and increased AF durations (P = .04). Picrosirius red staining of atrial tissues revealed increased interstitial fibrosis (P <.0001). There was also evidence of increased inflammatory cell infiltrates (P <.0001). Conclusion: Short-duration hypertension is associated with significant atrial remodeling characterized by atrial enlargement/dysfunction, interstitial fibrosis, inflammation, slowed/heterogeneous conduction, increased ERP, and greater propensity for AF. [Copyright &y& Elsevier]

Background: Abstract presentation at conferences provides the opportunity to rapidly communicate research findings. The outcome and impact of publications arising from cardiac electrophysiology abstracts are not known. Objective: The purpose of this study was to examine the characteristics of abstracts presented at the annual scientific sessions of Heart Rhythm Society (HRS), their publication rate, and the indexed impact of subsequent publications. Methods: Two independent database searches (MEDLINE and EMBASE) were performed by cross-referencing authors and keywords from abstracts originally presented at HRS in 2003. ISI Web of Knowledge was accessed for impact factors and citation rates. Results: A total of 790 abstracts were presented, of which 377 (47.7%) resulted in publication of an original article. Median time to publication was 1.39 years (interquartile range [IQR] 0.88–2.30 years), and the median impact factor and citation rate of published articles was 4.14 (IQR 3.48–11.05) and 10 (IQR 4–25), respectively. Experimental research abstract category (odds ratio [OR] 2.03, P <.001), randomized study design (OR 0.53, P = .02), and positive findings (OR 0.80, P = .06) were independently predictive of publication by stepwise logistic regression. Independent predictors of higher citation rates were randomized study design (P = .03) and impact factor of the publishing journal (P <.001). Conclusion: Almost half of all abstracts presented at HRS resulted in publication in journals with a high impact factor. Experimental research abstracts, those with a randomized study design, and those demonstrating positive findings were predictors of subsequent publication. Randomized study design and greater impact factor of the publishing journal were found to predict higher citation rates. [Copyright &y& Elsevier]

Introduction: Measuring the postpacing interval (PPI) and correcting for the tachycardia cycle length (TCL) is an important entrainment response (ER). However, it may be impossible to measure PPI due to electrical noise on the mapping catheter. To overcome this problem, 2 alternative methods for the assessment of ER have been proposed: N+1 difference (N+1 DIFF) and PPIR method. PPI-TCL difference (PPI − TCL) correlates very well with ER assessed by new methods, but the agreement with PPI − TCL was established only in relation to PPIR method. Moreover, it is not known which of these methods is superior in the assessment of ER. Methods: We analyzed 155 episodes of ER in 21 patients with heterogeneous reentrant arrhythmias. ER was estimated by PPI − TCL and by both alternative methods. Agreement between methods was assessed by means of the Bland-Altman test, kappa coefficient (κ), and correlation coefficient (r). Finally, a mathematical comparison of the alternative methods was performed. Results: The agreement between PPI − TCL and alternative methods was very good. For N+1 DIFF the mean difference was −1.86 ± 7.31 ms; kappa = 0.9; r = 0.98; for PPIR method the mean difference was −1.46 ± 7.65 ms; kapa = 0.92; r = 0.99. Agreement between both alternative methods was also very high: the mean difference of 0.5 ± 6.6 ms; kappa = 0.89; r = 0.99. The analysis of the equations used for calculation of ER by these methods revealed that essentially they were mathematically equivalent. Conclusion: Each of the alternative methods may be used for evaluation of ER when PPI − TCL cannot be assessed directly. Results obtained by both alternative methods are comparable. [ABSTRACT FROM AUTHOR]

Introduction: Sites of complex fractionated atrial electrograms (CFAEs) and highest dominant frequency (DF) have been proposed as critical regions maintaining atrial fibrillation (AF). This study aimed to determine the minimum electrogram recording duration that accurately characterizes CFAE or DF sites for ablation without unduly lengthening the procedure. Methods and Results: Fourteen patients with AF undergoing catheter ablation had high-density (498 ± 174 points) biatrial mapping performed during AF before ablation. At each point, 8-second electrograms were recorded. CFAE characterization using the NavX software provided a representation of electrogram complexity (CFE-mean). CFE-mean for each point from 7-, 6-, 5-, 4-, 3-, 2-, and 1-second subsamples were compared with the index 8-second CFE-mean. Offline spectral analysis defined DF as the frequency with greatest power, and DF of subsamples were compared with index DF. Index 8-second electrogram CFE-mean was 114 ± 20 ms for right atria and 102 ± 17 ms for left atria (P = 0.01); DF was 5.7 ± 0.8 Hz for right atria and 6.0 ± 0.8 Hz for left atria (P = 0.02). Means from shorter electrograms were nonsignificantly decreased for CFE-mean and overestimated for DF (P < 0.001). Mean absolute differences between subsampled and index values ranged from 3.3 to 20.1 ms for CFE-mean and 0.11 to 1.18 Hz for DF. Subsampled electrograms deviating >10% from index values ranged from 2.5 to 56% for CFE-mean and 3.5 to 41% for DF. Intraclass correlation coefficients ranged from 0.992 to 0.788 for CFE-mean and 0.897 to 0.233 for DF. Unacceptable differences from index values were found with CFE-mean and DF from electrograms <5 seconds. Conclusion: Electrograms of ≥5-second duration are required to accurately characterize CFAE and DF sites for ablation. [ABSTRACT FROM AUTHOR]

Evidence from noninvasive studies suggests magnesium has a differential effect on atrioventricular nodal (AVN) pathways. To further explore the electrophysiologic effects of intravenous magnesium sulfate (MgSO4) on supraventricular tachycardia, with particular reference to AVN conduction pathways, we studied 23 patients with supraventricular tachycardia at the time of electrophysiologic study. Tachycardia cycle length; AH, HV, and VA intervals; anterograde and retrograde Wenckebach thresholds; slow and fast pathway effective refractory periods (ERPs); accessory pathway ERP; right atrial and ventricular ERPs; blood pressure; and serum magnesium were evaluated before and after administration of MgSO4 during sustained tachycardia. AVN reentry was induced in 14 patients and atrioventricular reentry was induced in 9; 1 of the latter had dual AVN physiology with tachycardia using the slow pathway. Serum magnesium level increased from 0.88 ± 0.11 to 1.79 ± 0.14 mmol/L (p <0.0001). Magnesium increased tachycardia cycle length to a greater extent in those with dual AVN physiology than those without: 340 ± 54 to 370 ± 57 ms versus 347 ± 29 to 350 ± 30 ms (p = 0.01). This was associated with greater increase in AH interval in those with dual AVN physiology than in those without: 241 ± 59 to 270 ± 60 ms versus 144 ± 16 to 140 ± 20 ms (p = 0.003). Presence of dual AVN physiology was more frequently associated with reversion to sinus rhythm: 5 of 15 versus 0 of 8 (p = 0.06). MgSO4 did not alter other measured parameters. In conclusion, magnesium increases tachycardia cycle length and AH interval in patients with dual AVN physiology through a dominant effect on the slow AVN pathway. [Copyright &y& Elsevier]

Introduction: High-density three-dimensional (3D) mapping of the pulmonary vein (PV)-left atrial (LA) junction was performed to characterize spontaneous PV activity in humans. Methods and Results: The activation patterns of ectopic beats and of the initial 2 seconds of atrial fibrillation (AF) from the PVs were analyzed using a 64-poles basket catheter. A focal mechanism was defined as a discrete site of early and centrifugal activation. Continuous activity was considered as an activation covering ≥80% of the tachycardia beat-to-beat cycle length within the mapping field. In 35 patients, 123 spontaneous focal ectopic beats that did not induce AF and 95 that did induce AF were mapped. The mean coupling interval of ectopic discharges not inducing AF was 281 ± 70 msec versus 236 ± 90 msec for ectopies initiating AF (P ≤ 0.01). The first ectopic activity of all 218 arrhythmogenic events showed exclusively a focal mechanism. During the 95 episodes of AF initiation, one or two ectopic beats from the PVs initiated AF in the LA in 39%, a stable focal tachycardia was recorded in 14%, continuous activity with important changes in cycle length (35 ± 15 msec) suggestive of decremental or fibrillatory conduction was found in 18%, and in 29% the activation pattern could not be classified. No stable and sustained reentrant circuit could be identified by our mapping tool in the PV-LA junction. Conclusions: Arrhythmogenic activity from PVs in humans is predominantly due to discrete focal activity. [ABSTRACT FROM AUTHOR]

The article describes the case of a 74-year-old man with paroxysmal atrial fibrillation presented for ablation in view of progressive, drug-refractory symptoms. Highlights include exclusion of left atrial thrombus by transoesophageal echocardiography, an elevated jugular venous pressure and muffled heart sounds according to physical examination, and the possibility of delayed cardiac tamponade occurring after cryoablation.

Background: Left atrial (LA) linear lesions are effective in substrate modification for atrial fibrillation (AF). However, achievement of complete conduction block remains challenging and conduction recovery is commonly observed. The aim of the study was to investigate the localization of gap sites of recovered LA linear lesions. Methods and Results: Forty-eight patients with paroxysmal (n = 26) and persistent/permanent (n = 22) AF underwent repeat ablation after pulmonary vein (PV) isolation and LA linear ablation at the LA roof and/or mitral isthmus due to recurrences of AF or flutter. In 35 patients, conduction through the mitral isthmus line (ML) had recovered whereas roof-line recovery was observed in 30 patients. The gaps within the ML were distributed to the junction between left inferior PV and left atrial appendage in 66%, the middle part of the ML in 20%, and in 8% to the endocardial aspect of the ML while only 6% of lines showed an epicardial site of recovery. The RL predominantly recovered close to the right superior PV (54%) and less frequently in the mid roof or close to the left PV (both 23%). Reablation of lines required significantly shorter RF durations (ML: 7.24 ± 5.55 minutes vs 24.08 ± 9.38 minutes, RL: 4.24 ± 2.34 minutes vs 11.54 ± 6.49 minutes; P = 0.0001). Patients with persistent/permanent AF demonstrated a significantly longer conduction delay circumventing the complete lines than patients with paroxysmal AF (228 ± 77 ms vs 164 ± 36 ms, P = 0.001). Conclusions: Gaps in recovered LA lines were predominantly located close to the PVs where catheter stability is often difficult to achieve. Shorter RF durations are required for reablation of recovered linear lesions. Conduction times around complete LA lines are significantly longer in patients with persistent/permanent AF as compared to patients with paroxysmal AF. [ABSTRACT FROM AUTHOR]

Introduction: Organized atrial arrhythmias following atrial fibrillation (AF) ablation are typically due to recovered pulmonary vein (PV) conduction or reentry at incomplete ablation lines. We describe the role of nonablated anterior left atrium (LA) in arrhythmias observed after AF ablation. Methods: A total of 275 consecutive patients with paroxysmal (n = 200) or chronic (n = 75) AF had PV isolation with/without additional linear ablation at the mitral isthmus (n = 106), LA roof (n = 23), or both (n = 88). Organized arrhythmias occurring after ablation were evaluated utilizing activation and entrainment mapping. Results: Fourteen patients (11 female, 65 ± 13 years, 10 chronic AF, 10 structural heart disease) demonstrated tachycardia localized to the anterior LA, an area not targeted by prior ablation. Eight had ECG features during sinus rhythm suggestive of impaired anterior LA conduction at baseline. These arrhythmias demonstrated a distinctive ECG flutter morphology in 7 of 10 (70%) with discrete −/+ or +/−/+ aspect in inferior leads. Mapping the anterior LA revealed electrograms spanning the entire tachycardia cycle length (325 ± 125 msec). Entrainment was possible in all with a postpacing interval exceeding the tachycardia cycle length by 9 ± 10 msec. Electroanatomic mapping in 6 demonstrated small reentrant circuits rotating clockwise in 4 and counterclockwise in 2. Low-amplitude, fractionated mid-diastolic potentials with long duration (200 ± 80 msec) occupying 63 ± 22% of the cycle length were targeted for ablation resulting in termination and subsequent noninducibility. Conclusion: Organized arrhythmias occurring after AF ablation can be due to reentrant circuits localized to the anterior LA, predominantly in females with chronic AF, structural heart disease, and abnormal atrial conduction. They are characterized by a distinctive surface ECG and highly responsive to RF ablation at the slow conduction area. [ABSTRACT FROM AUTHOR]

Background: Pulmonary vein (PV) isolation and linear lesions are effective in eliminating paroxysmal atrial fibrillation (AF), but linear lesions probably are not required in all patients. Noninducibility of AF has been shown to be associated with freedom from arrhythmia in 87% of patients.Objectives: The purpose of this study was to prospectively evaluate the role of noninducibility in guiding a stepwise approach tailored to the patient.Methods: In 74 patients (age 53 +/- 8 years) with paroxysmal AF, PV isolation was performed during induced or spontaneous AF. If AF was inducible after PV isolation, one to two additional linear lesions were placed at the mitral isthmus and/or left atrial roof, with the endpoint of noninducibility of AF or atrial flutter. Inducibility (AF/atrial flutter, lasting > or = 10 minutes) was assessed using burst pacing at an output of 20 mA down to refractoriness from the coronary sinus and both atrial appendages.Results: In 42 patients (57%), PV isolation restored sinus rhythm and rendered AF noninducible. In the 32 patients with persistent or inducible AF after PV isolation, a single linear lesion achieved noninducibility in 20, whereas two linear lesions were required in 12 and resulted in conversion to sinus rhythm and noninducibility in 10. Using this stepwise approach, a total of 69 patients (93%) were rendered noninducible. During follow-up of 18 +/- 4 months, 67 patients (91%) were free from arrhythmia without antiarrhythmic drugs. Repeat procedures were performed in 23 patients: repeat ablation was required to consolidate prior targets in 15 patients (20%), and "new" linear lesions, which were not predicted by inducibility during the index procedure, were required in 8 (11%).Conclusion: Noninducibility can be used as an endpoint for determining the subset of patients with paroxysmal AF who require additional linear lesions after PV isolation. This tailored approach is effective in 91% of patients while preventing delivery of unnecessary linear lesions. [ABSTRACT FROM AUTHOR]

Objectives: The goal of this study was to characterize the origin of focal atrial tachycardias (AT). Background: Focal ATs originate from a small area and spread centrifugally; however, activation at the AT origin has not been characterized. Methods: Twenty patients with AT having failed prior ablation or occurring after atrial fibrillation ablation were studied. After excluding macro–re-entry, AT was mapped using a 20-pole catheter (five radiating spines; diameter 3.5 cm), performing vector mapping to identify the earliest activity followed by high-density mapping at the AT origin. Localized re-entry was considered if >85% of the tachycardia cycle length (CL) was observed within the mapping field and was confirmed by entrainment. Results: A total of 27 ATs were mapped to the pulmonary vein ostia (n = 5), and left (n = 16) and right atria (n = 6). A localized focus was evidenced at the site of origin in 19 ATs (70%), whereas in 8 (30%), localized re-entry was evidenced by 95.2 ± 4.5% of the tachycardia CL recorded within the mapping field and entrainment showed a post-pacing interval <20 ms longer than tachycardia CL (6 of 6 tested). Localized re-entry had a shorter CL (p = 0.009), slowed conduction at its origin (fractionated potential 115 ± 19 ms vs. 64 ± 22 ms, representing 49 ± 10% and 20 ± 10% of tachycardia CL, respectively; p < 0.0001), and were more often contiguous with regions of electrical silence or conduction abnormalities (88% vs. 32%; p = 0.01). In addition, mapping documented varying degrees of intra-atrial conduction block, preferential conduction (n = 5), and rapid bursts of myocardial activity (n = 1). At 11 ± 7 months, none have had recurrence of AT. Conclusions: High-density multielectrode mapping can be used to perform vector mapping to localize complex AT. It provides novel insight into the mechanisms of focal AT, distinguishing focal AT from localized re-entry. [Copyright &y& Elsevier]

Background: The relative contributions of different atrial regions to the maintenance of persistent atrial fibrillation (AF) are not known. Methods: Sixty patients (53 ± 9 years) undergoing catheter ablation of persistent AF (17 ± 27 months) were studied. Ablation was performed in a randomized sequence at different left atrial (LA) regions and comprised isolation of the pulmonary veins (PV), isolation of other thoracic veins, and atrial tissue ablation targeting all regions with rapid or heterogeneous activation or guided by activation mapping. Finally, linear ablation at the roof and mitral isthmus was performed if sinus rhythm was not restored after addressing the above-mentioned areas. The impact of ablation was evaluated by the effect on the fibrillatory cycle length in the coronary sinus and appendages at each step. Activation mapping and entrainment maneuvers were used to define the mechanisms and locations of intermediate focal or macroreentrant atrial tachycardias. Results: AF terminated in 52 patients (87%), directly to sinus rhythm in 7 or via the ablation of 1–6 intermediate atrial tachycardias (total 87) in 45 patients. This conversion was preceded by prolongation of fibrillatory cycle length by 39 ± 9 msec, with the greatest magnitude occurring during ablation at the anterior LA, coronary sinus and PV-LA junction. Thirty-eight atrial tachycardias were focal (originating dominantly from these same sites), while 49 were macroreentrant (involving the mitral or cavotricuspid isthmus or LA roof). Patients without AF termination displayed shorter fibrillatory cycles at baseline: 130 ± 14 vs 156 ± 23 msec; P = 0.002. Conclusion: Termination of persistent AF can be achieved in 87% of patients by catheter ablation. Ablation of the structures annexed to the left atrium—the left atrial appendage, coronary sinus, and PVs—have the greatest impact on the prolongation of AF cycle length, the conversion of AF to atrial tachycardia, and the termination of focal atrial tachycardias. [ABSTRACT FROM AUTHOR]

Background: Catheter ablation of atrial fibrillation (AF) is challenging in patients with long-standing persistent AF. The clinical outcome and subsequent arrhythmia recurrence after using an ablation method targeting multiple left atrial sites with the aim of achieving acute AF termination has not been characterized. Methods: Sixty patients (mean age: 53 ± 9 years) with persistent AF (mean duration: 17 ± 27 months) were prospectively followed after catheter ablation. Catheter ablation targeting the following sites was performed in a random sequence: (i) electrical isolation of all pulmonary veins (PV); (ii) disconnection of other thoracic veins; (iii) atrial ablation at sites possessing complex electrical activity, activation gradients, or short cycle lengths. Finally, linear ablation of the LA roof and mitral isthmus was performed if sinus rhythm was not restored following energy delivery to the above sites. At 1, 3, 6, and 12 months after ablation, patients underwent clinical review and 24-hour ambulatory ECG monitoring to identify asymptomatic arrhythmia. Repeat mapping and catheter ablation was performed in any patient experiencing recurrent atrial tachycardia (AT). Clinical success was defined as the absence of any sustained atrial arrhythmia. Results: AF terminated during ablation in 52 patients (87%). The fluoroscopy and procedural durations were 84 ± 30 minutes and 264 ± 77 minutes, respectively. Three months after ablation, sustained ATs were documented in 24 patients (associated with AF in 2). Mapping in 23 patients showed a single AT in 7 while multiple ATs were observed in 16. Macroreentry was confirmed to be due to gaps in the ablation lines, while focal ATs originated from discrete sites or isthmuses near the left atrial appendage, coronary sinus, pulmonary veins, or fossa ovalis; these sites were similar to those at which the greatest impact was observed on the fibrillatory process during the initial ablation procedure. After repeat ablation, at 11 ± 6 months of follow-up, 57 patients (95%) were in sinus rhythm and 3 developed recurrent AF or AT. All patients in sinus rhythm demonstrated improved exercise capacity and all but 2 had evidence of atrial transport as assessed by Doppler echocardiography (mitral A wave velocity 34 ± 17 cm/sec) by 6 months. Conclusion: Catheter ablation of long-lasting persistent AF associated with acute AF termination achieves medium to long-term restoration and maintenance of sinus rhythm in 95% of patients. Arrhythmia recurrence in the majority of patients is AT. [ABSTRACT FROM AUTHOR]

Fever and Idiopathic VF. Introduction: Ventricular fibrillation (VF) is the main mechanism of sudden cardiac death. The clinical precipitants of sudden cardiac death due to idiopathic VF are poorly characterized. Emerging evidence implicates triggers originating predominantly from the distal Purkinje arborization and the right ventricular outflow tract. Methods and Results: We report three patients without structural heart disease or repolarization abnormalities in whom a febrile illness was the only concurrent disease associated with unexpected sudden cardiac death due to VF storm. An automated defibrillator was implanted in all three patients. In one patient with persistent recurrent VF episodes, mapping demonstrated the origin of these triggers was from the Purkinje arborization of the anterior wall of the right ventricle. Ablation at a site of earliest activation during ectopy, where pace mapping was concordant and Purkinje potential preceded the onset of ventriculogram, resulted in suppression of all arrhythmias. After follow-up of 22,9, and 18 months in the three patients, no ventricular arrhythmias have been recorded. Conclusion: We present a series of patients in whom an apparently benign febrile illness was associated with malignant ventricular arrhythmias in the absence of cardiac disease or other factors known to precipitate sudden cardiac death. Physicians should be aware of this possible phenomenon in cases of febrile illness associated with syncope. [ABSTRACT FROM AUTHOR]

The goal of this study was to describe the mapping and ablation of polymorphic ventricular tachycardia (VT) after myocardial infarction (MI).The initiating mechanisms of polymorphic VT after MI have not been reported.Five patients (four males; age 61 ± 7 years) with recurrent episodes of polymorphic VT after anterior MI (left ventricular ejection fraction 32 ± 7%) despite revascularization and antiarrhythmic drugs were studied. All patients demonstrated frequent ventricular premature beats (PBs) initiating polymorphic VT. Pace mapping and activation mapping were used to identify the earliest site of PB activity. The presence of a Purkinje potential preceding PB defined its origin from the Purkinje network. Electroanatomic voltage mapping was performed to delineate the extent of MI.The PBs were observed in all cases to arise from the Purkinje arborization in the MI border zone. These PBs were right bundle-branch block in all five patients, with morphologic variations in the limb leads in four; one also had a left bundle-branch block morphology. The coupling interval of the PB to the preceding QRS complex demonstrated significant variations (320 to 600 ms). During PB, the Purkinje potential at the same site preceded the QRS complex by 20 to 160 ms and was associated with different morphologies. Repetitive Purkinje activity was documented during polymorphic VT. Splitting of Purkinje activity and Purkinje to muscle conduction block were also observed. Ablation at these sites eliminated all PBs. At 16 ± 5 months follow-up using defibrillator memory interrogation, no patient has had recurrence of arrhythmia.The Purkinje arborization along the border-zone of scar has an important role in the mechanism of polymorphic VT in patients after MI. Ablation of the local Purkinje network allows suppression of polymorphic VT. [Copyright &y& Elsevier]