Focal Atrial Fibrillation Research Articles

Prevalance of incessant form of atrial fibrillation by superior vena cava (svc) firing:simplified svc and sinus node mapping(sss map) to avoid sinus node injury

Abstract Background The superior vena cava (SVC) is known as a major source of atrial fibrillation(AF), non-pulmonary vein AF foci (NPVAF). In some cases, an incessant form of AF (iAF) by SVC firing prevents obtaining the sinus node location, and anatomical SVC isolation has a risk of sinus node injury (SNI). Objective This study was aimed to explore the frequency of iAF by SVC firing and the efficacy of the simplified mapping strategy to avoid SNI. Methods Consecutive AF ablation procedures in the 3 centers were retrospectively investigated including the NPVAF prevalence. Simplified SVC/SN mapping (SSS-map: Obtaining the top-end of the SVC potential and >4points with 5-10mm spacing in the upper lateral side of the right atria (RA) for roughly locating the earliest activation site in sinus rhythm) was performed before PV isolation in the last 138 patients. In case of the initial rhythm at the procedure was atrial fibrillation, cardioversion was performed for obtaining the SSS-map. In the cases in which the high-density mapping catheters were available, the high-density activation maps of the RA in sinus rhythm were obtained to investigate the dislocation of the earliest activation site of the SSS map from the SN location. When SVC isolation was required due to iAF, SVC isolation line was designed based on the location of the top-end of the SVC potential during AF and ablative linear lesions were created to keep the distance of 5-10 mm above the second earliest activation site. Results A total of 1160 procedures in 1089 patients (male: 736[63.4%], age: 69.9, paroxysmal AF: 544[49.9%], first session: 997[85.9%]) was investigated. Prevalence of NPVAF was revealed in 160 of the all procedures (13.7%) (the SVC: 64, the posterior wall of the left atria: 24, the coronary sinus: 19, and others: 53). 16 of 160 NPVAFs (10.0%) developed to iAF by SVC firing. The SSS-map was successfully obtained in all of the last 138 patients (Initial rhythm at the procedure: AF 43.7%, Mapping time: 1.3±0.6 min, number of obtained points: 8.4±1.3). In 21 patients in which the high-density RA map was obtained, the SN dislocation distance was 5.1±2.2mm between the SSS map and the high-density RA map. Five of 138 developed to iAF by SVC firing, and SVC isolation based on the SSS-map was successfully achieved without SNI in the cases. Conclusion This study indicated iAF driven by SVC firing after PV isolation occurred in certain number of patients. The SSS-map before PV isolation was practical and showed the potential to be the mapping strategy avoid the SN injury in such cases.

Studies on Atrial Fibrillation and Venous Thromboembolism in the Past 20 Years: A Bibliometric Analysis Via CiteSpace and VOSviewer.

The conjunction of atrial fibrillation (AF) and venous thromboembolism (VTE) is common in clinical practice. Over the last 2 decades, a significant number of articles (2500) have been published about AF and VTE. To effectively analyze and present these vast amounts of information, this study uses bibliometric research methods to categorize and consolidate these publications. The number of publications has increased yearly, especially since 2012. The United States was the most prolific country, with 1054 studies published. The most productive institution was McMaster University. Gregory Y.H. Lip was the most prolific author. The keyword analysis identified that the research focuses from 2003 to 2014 were factor Xa inhibitor, dabigatran etexilate, direct thrombin inhibitor, double-blind, deep vein thrombosis, molecular weight heparin, stroke prevention, etc. From 2015 to 2016, research mainly focused on venous thromboembolism, antithrombotic therapy, anticoagulant, warfarin, atrial fibrillation, stroke, and pulmonary embolism. Studies during 2017 to 2022 focused on apixaban, direct oral anticoagulant, rivaroxaban, dabigatran, hemorrhage, edoxaban, medicine efficacy and safety, risk factors, clinical management, and vitamin K antagonists. Since 2018, novel oral anticoagulants have been the most commonly used keywords. On the whole, most studies of AF and VTE focus on pathogenesis and therapeutic drugs. The causal relationship between AF and VTE, the effectiveness and safety of novel oral anticoagulants in the treatments, the anticoagulant regimen of AF and VTE co-disease, and the treatment regimen for vulnerable populations such as the elderly or obese people were the focus of current research and will continue to be the central point of future research.

Atrial cardiomyocytes from a canine model of atrial fibrillation demonstrate reduced force development and altered expression of contractile proteins.

Atrial fibrillation (AF) is the most common cardiac rhythm disturbance and associates with worse outcomes in cardiac contractile-related diseases including cardiomyopathy. As most studies surrounding AF focus on the electrophysiology of the disease, there is little known about cardiomyocyte contractile function in AF. We used atrial tissue from an established atrial tachypacing canine model of AF. Whole protein lysates were collected from the atria to conduct mass spectrometry analysis showing dysregulation of numerous molecular pathways, including contractility. Skinned atrial cardiomyocytes were isolated from the tissue for force calcium and passive tension experiments. Force calcium experiments showed a significant reduction in the maximum force of contraction of AF cardiomyocytes. To explain this, myosin heavy chain (MHC) isoform expression was evaluated because isoform switching is known to alter force of contraction. Decreased percent beta expression was found, explaining the reduction of force due to MHC alpha's capacity for reduced force of contraction. AF cardiomyocytes showed increased calcium sensitivity of force development, which may translate to prolonged contraction with slower relaxation in vivo. A significant reduction in S100A1 was seen in the AF samples via mass spectrometry, which is associated with increased calcium sensitivity. Prolonged contraction along with reduced force of each contraction could support the development of atrial clots. Atrial cardiomyocytes from the AF hearts demonstrated a significant reduction in the passive tension. Evaluation of titin isoform expression, which is known to alter passive tension, showed increased titin degradation, supporting the capacity for atrial dilation in vivo. Discerning the role of contractility in the pathology of atrial fibrillation could provide novel avenues of AF treatment, especially in instances where it is associated with contractile diseases.

S2384 The First Case of Water Immersion Endoscopy in the Definitive Diagnosis of Atrio: Esophageal Fistula

Introduction: Atrial fibrillation (AF) is the most common heart rhythm disorder with estimated global prevalence of 33.5 million. Catheter ablation is the treatment modality of choice for refractory AF. Atrio-esophageal fistula (AEF) is a serious complication of catheter ablation. Diagnosis is critical to the management of AEF, and includes computed tomography of the chest, esophagram and esophagogastroduodenoscopy (EGD). Prompt diagnosis of AEF is essential for survival. Case Description/Methods: A 56-year-old male with AF presented with fever, fatigue and bilateral leg weakness. Twenty days prior to presentation he underwent pulmonary vein isolation radiofrequency ablation and discharged the following day. Upon re-presentation his vitals were notable for fever and tachycardia. Labs revealed a normal white count and hemoglobin, and elevated lactate and troponin. One hour after arrival he developed complex focal seizure and AF with rapid ventricular rate followed by respiratory decompensation requiring intubation. His blood cultures revealed Streptococcus mitis and Gemella haemolysans. His MRI disclosed numerous bilateral emboli concerning for endocarditis, however TEE did not reveal any valvular vegetation, thus proposing AEF as a possible complication accounting for the emboli. CT chest angiogram revealed subtle irregularity along the posterior wall of the left atrium (figure A), but did not provide conclusive evidence to warrant high-risk cardiothoracic surgery. Water immersion EGD was performed to diagnose and localize the fistula, revealing esophageal defect in the proximal esophagus with movement of non-bloody debris through the tract (figure B). One hemostatic clip was placed near the tract to assist with localization for surgical closure. The following day the patient underwent right thoracotomy with placement of intercostal muscle flap to fistula (Figure C). Discussion: AEF is a rare complication of radiofrequency ablation therapy for AF. High mortality rate is primarily attributed to major cerebrovascular morbidity from septic thrombi. Currently there is no effective modality to visualize AEF safely and reliably. Water immersion colonoscopy allows for completion of difficult colonoscopies, decreased insertion pain, and increased adenoma-detection rates. This technique was applied to identify the AEF. Water immersion EGD is an important modality that can confidently be considered within the diagnostic armamentarium of gastroenterologists to ensure safe and rapid diagnosis and treatment of AEF.Figure 1.: 1: (A) Illustrates a subtle contour abnormality involving the posterior wall of the left atrium (arrow) concerning for AEF (B) Water immersion endoscopy illustrating 3mm defect (arrow) in the wall of the esophagus (C) Underwent right thoracotomy to access AEF. This image highlights 3mm fistula site (arrow) that is approximated to be at the midpoint of the atrium.

Efficacy and Safety of Anticoagulant Therapy in Patients With Various Forms of Atrial Fibrillation After Interventional Treatment. Results of a Three-Year Follow-up.

Aim To evaluate efficacy and safety of the anticoagulant therapy in patients with atrial fibrillation (AF) during a 36-month follow-up after an interventional treatment.Material and methods This study included 302 patients aged 29 to 81 years with various forms of AF. Catheter ablation (CA) of AF foci was performed for all patients. The patients were divided into 3 groups: group 1 with paroxysmal AF, group 2 with persistent AF, and group 3 with longstanding persistent AF. Two subgroups were isolated in each group, with effective and ineffective CA. Results of the follow-up were analyzed at 12, 24, and 36 months after discharge from the hospital. The follow-up interview recorded complaints of palpitation attacks, effectiveness of administered CA, compliance with the treatment, adverse clinical outcomes, including thromboembolic complications (TEC), bleeding, and hospitalizations.Results Efficacy of the interventional treatment for 36 months was 65.3 % in patients with paroxysmal AF, 59.7 % in patients with persistent AF, and 57.1 % in patients with longstanding persistent AF. Patients with paroxysmal AF and effective CA had no adverse events throughout the same period during the antithrombotic treatment (ATT). In contrast, the group with ineffective ablation had both TEC and hemorrhagic complications during the ATT. In the group with persistent AF and effective CA throughout the follow-up period, TECs were less frequent than in the group of ineffective ablations during the ATT treatment. Patients with longstanding persistent AF and effective CA throughout the follow-up period, had no TECs in contrast to patients with ineffective ablation during the ATT treatment. There were no fatal outcomes in patients with effective procedure.Conclusion A successful CA procedure for AF provides a significant decrease in the risk of ischemic stroke. Furthermore, the invasive strategy does not increase the risk of major and minor bleedings.

Long-term amelioration of an early-onset familial atrial fibrillation model with AAV-mediated in vivo gene therapy

Atrial fibrillation (AF) is a common cardiac disease with high prevalence in the general population. Despite a mild manifestation at the onset stage, it causes serious consequences, including sudden death, when the disease progresses to the late stage. Most available treatments of AF focus on symptom management or alleviation, due to a lack of fundamental knowledge and the fact that considerable variations of AF exist. With the popularisation of the next-generation sequencing technology, several causal genetic factors, including MYL4, have been discovered to contribute to AF, giving hope to developing its gene therapies. In this study, we attempted to treat a previously established rat AF model, which carried Myl4E11K/E11K loss of function mutation, via overexpression of exogenous wild-type Myl4 by AAV9 vectors. Our results showed that delivery of Myl4 expressing AAV9 to postnatal rat models rescued the symptoms of AF, indicating the therapeutic potential that early gene therapy intervention can achieve long-term effects in treating cardiac arrhythmias caused by gene mutations.

Incidence, Risk Factors, and Outcomes of Atrial Arrhythmias in Adult Patients With Atrioventricular Septal Defect.

This study aimed to assess the incidence, associated factors, and outcomes of atrial arrhythmias in adults with atrioventricular septal defect (AVSD). Data regarding atrial arrhythmias in adults with AVSD are particularly scarce. Data were analyzed from a multicentric cohort of adult patients with AVSD. Lifetime cumulative incidences of atrial arrhythmias were studied. Multiple logistic regression models were used to identify risk factors. A total of 391 patients (61.6% women) were enrolled with a mean age of 36.3 ± 16.3 years and a mean follow-up of 17.3 ± 14.2 years after initial surgical repair. Overall, 98 patients (25.1%) developed at least 1 episode of atrial arrhythmia at a mean age of 39.2 ± 17.2 years. The mean ages of patients at first episode of intra-atrial re-entrant tachycardia (IART)/ focal atrial tachycardia (FAT) and atrial fibrillation were 33.7 ± 15.3 and 44.3 ± 16.5 years, respectively. The lifetime risks for developing atrial arrhythmia to ages 20, 40, and 60 years were 3.7%, 17.8%, and 55.3%, respectively. IART/FAT was the leading arrhythmia until the age of 45, then atrial fibrillation surpassed IART/FAT. Age (odds ratio [OR]: 1.4; 95% confidence interval [CI]: 1.2-1.6), number of cardiac surgeries (OR: 4.1; 95%CI: 2.5-6.9), left atrial dilatation (OR: 3.1; 95%CI: 1.4-6.8), right atrial dilatation (OR: 4.1; 95%CI: 1.7-10.3), and moderate or severe left atrioventricular valve regurgitation (OR: 3.7; 95%CI: 1.2-11.7) were independently associated with a higher risk of atrial arrhythmias, whereas the type of AVSD and the age at repair were not. The occurrence of atrial arrhythmias was associated with pacemaker implantation (41.8% vs. 8.5%; P< 0.001), heart failure (24.5% vs. 1.0%; P< 0.001), and cerebrovascular accidents (11.2% vs. 3.4%; P = 0.007). The lifetime risk of atrial arrhythmias in patients with AVSD is considerable with more than half of patients developing≥1 atrial arrhythmia by the age of 60 and is associated with a significant morbidity. The risk in partial/intermediate AVSD is as high as in complete AVSD and is not impacted by age at repair.

Recurrent atrial fibrillation after initial cryoballoon ablation: New perspectives for intensive ablation in right superior pulmonary vein ostium for atrial fibrillation

A significant proportion of patients with recurrent atrial fibrillation (AF) require repeat radiofrequency (RF) ablation after cryoballoon (CB) ablation. However, little is known about the pulmonary vein (PV) potential reconnection to left atrium and localization of gaps in the initial lesion sets following cryoablation in patients with recurrent AF. The data of 29 consecutive patients with repeat RF ablation for recurrent AF were analyzed. During the second ablation procedures, PV foci of AF were explored in 116 PVs by the CARTO system. All patients had complete PV isolation from initial cryoablation procedure. The fluoroscopy duration, mean cryoablation time and mean cryoablation frequency were lowest for the right superior pulmonary vein (RSPV) (58.69 ± 9.18 s, 185.10 ± 49.25 s and 1.07 ± 0.26; p = 0.024, p = 0.042 and p = 0.032). A significantly higher incidence of conduction gaps per patient was found for the RSPVs compared to the other PVs (p < 0.05 or p < 0.01). For RSPVs, it seemed that gaps were predominantly located at the anterior segment (22 gaps) and inferior segment (22 gaps). RSPV reconnection was independently related to a lower risk of major adverse events after the second ablation during follow up in the study patients (HR 0.275, 95%CI 0.078–0.967, p = 0.044). AF recurrence in patients after cryoablation is significantly associated with conduction gaps in the anterior and inferior segments of RSPVs. Various ablation strategies of close touch of CB on anterior and inferior segments of RSPV ostium, more freezing time and frequency for RSPV may help achieving durable PV isolation during follow up.

Exosomes in atrial fibrillation: therapeutic potential and role as clinical biomarkers.

Atrial fibrillation (AF), the most common cardiac arrhythmia, is a global epidemic. AF can cause heart failure and myocardial infarction and increase the risk of stroke, disability, and thromboembolic events. AF is becoming increasingly ubiquitous and is associated with increased morbidity and mortality at higher ages, resulting in an increasing threat to human health as well as substantial medical and social costs. Currently, treatment strategies for AF focus on controlling heart rate and rhythm with medications to restore and maintain sinus rhythm, but this approach has limitations. Catheter ablation is not entirely satisfactory and does not address the issues underlying AF. Research exploring the mechanisms causing AF is urgently needed for improved prevention, diagnosis, and treatment of AF. Exosomes are small vesicles (30-150nm) released by cells that transmit information between cells. MicroRNAs in exosomes play an important role in the pathogenesis of AF and are established as a biomarker for AF. In this review, a summary of the role of exosomes in AF is presented. The role of exosomes and microRNAs in AF occurrence, their therapeutic potential, and their potential role as clinical biomarkers is considered. A better understanding of exosomes has the potential to improve the prognosis of AF patients worldwide, reducing the global medical burden of this disease.

Immuno-Electrophysiological Mechanisms of Functional Electrical Connections Between Recipient and Donor Heart in Patients With Orthotopic Heart Transplantation Presenting With Atrial Arrhythmias.

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Presence of non-pulmonary vein foci in patients with atrial fibrillation undergoing standard ablation of pulmonary vein isolation: Clinical characteristics and long-term ablation outcome.

BackgroundThe clinical characteristics of atrial fibrillation (AF) resulting from non-pulmonary vein (PV) triggers remain unknown. This study aimed to evaluate the clinical characteristics of patients with AF caused by non-PV triggers, localization of non-PV foci, clinical differences, and clinical outcomes after catheter ablation in each AF focus.MethodsA total of 2967 patients who underwent initial catheter ablation for paroxysmal or persistent AF were examined. After PV isolation, all patients underwent high-dose isoproterenol infusion to assess the existence of non-PV foci.ResultsNon-PV foci were identified in 564 patients (19.2%). The localization of successfully ablated non-PV foci in 514 patients were the superior vena cava (SVC: 213 cases), interatrial septum (IAS: 125 cases), coronary sinus (CS: 98 cases), right atrium (RA: 125 cases), left atrium (LA: 114 cases), and unmappable (50 cases). Multivariate analysis revealed that female gender, low body mass index (BMI), non-paroxysmal AF (PAF), and sick sinus syndrome were independent and significant indicators of non-PV foci. In the multivariate analysis of each AF focus, female gender, low BMI, and non-PAF were significant predictors of IAS and CS foci, RA and IAS foci, and CS foci, respectively. In addition, dilatation of the LA was significantly associated with LA foci, whereas RA, LA, IAS, and CS foci were associated with AF recurrence.ConclusionThese findings could help to identify patients at a higher risk of AF caused by non-PV triggers and clarify the clinical difference according to the localization of non-PV foci.

Abstract 16564: Location of Persistent Atrial Fibrillation Drivers Based on Body Surface Mapping: A Systematic Review and Metanalysis

Introduction: Body Surface Mapping (BSM) is a non-invasive electrocardiogram-based mapping system that is used to identify localized drivers in patients with persistent Atrial Fibrillation (AF). Mapping of local drivers is becoming increasingly important in guiding treatment of atrial fibrillation but may not be readily available. We conducted a systematic review to determine the most prevalent atrial regions of AF driver activity identified with BSM. Methods: Electronic literature searches were performed across PubMed, Google Scholar, Cochrane, CINAHL, Web of science, EMBASE databases up to January 2019, for studies that utilized BSM to identify and report localized focal and rotor (reentrant) driver activity. Prevalence of drivers, as a percentage, were recorded for every region according to the Bordeaux Biatrial Schema. Random-effects model was used to calculate weighted averages with the corresponding 95% confidence interval (CI). Results: Total of 468 unique studies were identified and reviewed. 4 prospective cohort studies were included in the final analysis—of which 3 were single-center and 1 was multi-centered; totaling 336 patients. The mean age was 62.8 (±5.41) and 73% were males. The three most prevalent regions with persistent AF foci activity were region 1 (left pulmonary veins and left appendage): 59% (CI 48-71), followed by region 4 (upper half of right atrium and appendage): 31% (CI 12-54), and region 2 (right pulmonary veins and posterior interatrial groove): 19% (CI 7-34). The three most prevalent regions of persistent AF rotor activity were region 3 (inferior and posterior left atrium): 71% (CI 32-98), region 1: 70% (CI 21-100), and region 2: 70% (CI 25-99). Conclusion: In patients with persistent AF, majority of localized drivers seem to originate from specific atrial regions based on BSM.

Vein of Marshall visualization in cardiac computed tomography

Abstract The oblique vein of the left atrium (vein of Marshall) is a small vessel that descends obliquely on the back of the left atrium and ends in the coronary sinus near the area where great cardiac vein continues into the coronary sinus. Its cannulation can be useful, e.g. before selected electrophysiology procedures such as paroxysmal focal atrial fibrillation ablation. Because the vein of Marshall should also be avoided at the site of the implantation of the left ventricle lead, knowledge about its existence, position or diameters could be useful. There is a lack of complex data about the possibilities of visualizing the vein of Marshall in cardiac computed tomography. Methods 354 patients were included into the research. Cardiac computed tomography (Aquilion 64, Toshiba: 64 slices, 0.5 mm; retrospective gating; contrast enhanced) was performed for all of the patients. A precise retrospective analysis of the CT data in all phases (every 10%) of the cardiac cycle during post processing was performed including searching for the target vein by using Vitrea workstations (Vital Images). Both multi planar reformatted reconstructions (MPR) and 3D volume renderings were used. The analyses were performed by two experienced researchers (more than 200 coronary venous system analyses previously performed). Results The vein of Marshall was found in 66 of the 354 patients (16.6%). An example of the visualization is presented in the figure below (MPR and 3D volume rendering). Its ostium to coronary sinus was found an average of 42.6±10.8 mm from the coronary sinus ostium to the right atrium. This value was statistically higher (p=0.0082) in the men (45.3±11.2) compared to the women (38.5±9.7). The vein of Marshall is a small vessel; its average diameter was 1.8±0.8 mm and length of the visible vessel that was measured was 8.7±7.5 mm. It was visualized statistically more frequently (p=0.0009) in the end-systolic phases (30–40–50% RR; 68.85% cases) compared to the end-diastolic phases (70–80% RR; 21.31% cases). Occasionally, it was optimally visualized in the other phases (9.83%). Conclusion It is possible to visualize the vein of Marshall using cardiac computed tomography. Because it exists in about 20% of population, during visualization, special attention needs to paid to obtaining quality images in CT especially in the end-systolic phases. Vein of Marshall imaging (VR, MPR) Funding Acknowledgement Type of funding source: None

Feasibility of superior vena cava isolation in patients with cardiac implantable electronic devices.

Some patients with cardiac implantable electronic devices (CIEDs) require atrial fibrillation (AF) ablation, and the superior vena cava (SVC) has been identified as one of the most common non-pulmonary vein foci of AF. This study aimed to investigate the interaction between SVC isolation (SVCI) and CIED leads implanted through the SVC. We studied 34 patients with CIEDs who had undergone SVCI as part of AF ablation (CIED group), involving a total of 71 CIED leads. A similar number of age-, sex-, and AF type-matched patients without CIEDs formed a control group (non-CIED group). Patients' background and procedural characteristics were compared between the groups. In the CIED group, lead parameters before and after AF ablation were compared, and lead failure after AF ablation was also examined in detail. Procedural characteristics other than fluoroscopic time were similar in both groups. The success rate of SVCI after the final ablation procedure was 91.2% in the CIED group and 100% in the non-CIED group; however, these differences were not statistically significant. Lead parameters before and after the AF ablation did not significantly differ between the two groups. Lead failure was observed in three patients, with a sensing noise in one patient and an impedance increase in two patients after SVCI. SVCI was achievable without lead failure and significant change in lead parameters in most patients with CIEDs; however, it should be noted that lead failure was observed in 8.8% of the study patients after SVCI.

Clinical Factors Associated with a Successful Catheter Ablation Outcome in Elderly Patients with Atrial Fibrillation.

Catheter ablation is currently an established treatment for symptomatic paroxysmal atrial fibrillation (AF). We focused on elderly patients with a high prevalence of AF and attempted to identify the clinical factors associated with unsuccessful ablation outcomes.Among 735 consecutive patients who underwent AF ablation procedures, 108 (14.7%, 66 men) aged ≥ 75 years were included. Of them, 80 had paroxysmal AF, and the remaining 28 non-paroxysmal AF. All patients underwent pulmonary vein (PV) isolation and occasionally additional ablation. When AF recurred, redo ablation procedures were performed if the patient so desired.The mean number of ablation procedures was 1.1 ± 0.4 times per patient. During a mean follow-up of 38.7 ± 21.7 months, sinus rhythm was maintained in 100 patients (92.6%) without any antiarrhythmic drugs, but not in the remaining 8 (7.4%). Left atrial diameter (LAD, P < 0.001), left ventricular (LV) systolic diameter (P < 0.001), LV diastolic diameter (P = 0.001), non-PV AF foci (P = 0.036), and diabetes (P = 0.045) were associated with unsuccessful ablation procedures. Multivariate logistic regression analysis revealed a large LAD and non-PV AF foci were significant independent predictors of AF recurrences, with odds ratios of 0.76 (P = 0.019) and 0.04 (P = 0.023), respectively. In a total of 124 procedures, one major (0.8%) and 11 minor (8.9%) complications occurred.In elderly AF patients, catheter ablation of AF is effective and safe. Non-PV AF foci and a large LAD were independent clinical predictors of unsuccessful AF ablation outcomes.

Focal source and trigger mapping in atrial fibrillation: Randomized controlled trial evaluating a novel adjunctive ablation strategy

Intraoperative mapping has demonstrated focal activations during human atrial fibrillation (AF). These putative AF sources can manifest sustained periodic bipolar and unipolar QS electrograms (EGMs). We have automated the detection of these EGM features using our validated Focal Source and Trigger (FaST) computational algorithm. The purpose of this study was to conduct a randomized controlled pilot evaluating the feasibility and efficacy of FaST mapping/ablation as an adjunct to pulmonary vein isolation (PVI) in reducing AF recurrence. We randomized 80 patients with high-burden paroxysmal or persistent AF (age 61 ± 10 years; 75% male) to PVI alone (n = 41) or PVI+FaST mapping/ablation (n = 39). The primary endpoint was time to AF recurrence >30 seconds between 3 and 12 months after 1 procedure. FaST sites were identified in all but 1 patient and were localized to pulmonary vein (PV) (2.1 ± 1.1 per patient) and extra-PV regions (2.8 ± 1.4 per patient). FaST mapping and ablation times were 27 ± 9 minutes and 8.5 ± 5 minutes, respectively. Patients with AF termination during ablation had greater AF cycle length prolongation with PVI+FaST than PVI (Δ20 ± 14 ms vs Δ5 ± 17 ms; P = .046). Freedom from AF recurrence at 12 months was higher in PVI+FaST vs PVI for patients off antiarrhythmic drugs (74% vs 51%; hazard ratio 0.48; 95% confidence interval 0.21-1.08; P = .064) but did not quite reach statistical significance. Major adverse events were similar between the 2 groups. In this randomized controlled pilot, real-time FaST mapping provided an intuitive, automated approach for localizing focal AF sources. FaST ablation as an adjunct to PVI may reduce AF recurrence, which requires verification with a larger multicenter trial.

Stroke Referrals from Nursing Homes: High Rate of Mimics and Late Presentation

Background: Stroke has become a treatable condition with increasing evidence of treatment benefits in older people. However, stroke mimics in geriatric patients are especially prevalent, causing incorrect suspicion and consecutive burden to patients and emergency room resources. We therefore examined the dimension of this problem by investigating emergency room admissions from nursing homes for suspected stroke. Methods: We performed a retrospective cohort study of all nursing home residents who were admitted to the neurological emergency room of our primary and tertiary care university hospital between 2013 and 2015. Patients were further divided into those with confirmed stroke and stroke mimics after diagnostic stroke work-up. Results: Of 419 nursing home patients referred to the emergency room, nearly one third had suspected stroke (n = 126; mean age: 78 ± 14 years, polypharmacy rate: 77%). Of those, 43 (34%) had a confirmed stroke (ischaemic: n = 34; haemorrhagic: n = 9) and 83 (66%) had stroke mimics after diagnostic work-up. Only one patient underwent intravenous thrombolysis, followed by mechanical thrombectomy for middle cerebral artery occlusion. Prehospital delay (47%) and multimorbidity-associated contraindications (27%) were the main reasons for withholding recanalization therapy. Among the stroke-mimicking conditions, infectious diseases (24%) and epileptic seizures (20%) were the most frequent. Multivariate analysis identified focal deficits (OR 16.6, 95% CI 4.3–64.0), atrial fibrillation (OR 3.9, 95% CI 1.5–10.5) and previous stroke (OR 3.2, 95% CI 1.2–8.9) as indicators that were associated with stroke. Conclusions: In our region, nursing home referrals for suspected stroke have a high false positive rate and occur delayed, which most often precludes specific stroke treatment in addition to multimorbidity. Such problems may also exist in other centres and highlight the need for targeted educational and organizational efforts. Simple indicators as identified in this study may help to sort out patients with true stroke more efficiently.

Atrial Infarction-Induced Spontaneous Focal Discharges and Atrial Fibrillation in Sheep: Role of Dantrolene-Sensitive Aberrant Ryanodine Receptor Calcium Release.

The mechanisms underlying spontaneous atrial fibrillation (AF) associated with atrial ischemia/infarction are incompletely elucidated. Here, we investigate the mechanisms underlying spontaneous AF in an ovine model of left atrial myocardial infarction (LAMI). LAMI was created by ligating the atrial branch of the left anterior descending coronary artery. ECG loop recorders were implanted to monitor AF episodes. In 7 sheep, dantrolene-a ryanodine receptor blocker-was administered in vivo during the 8-day observation period (LAMI-D, 2.5 mg/kg, IV, BID). LAMI animals experienced numerous spontaneous AF episodes during the 8-day monitoring period that were suppressed by dantrolene (LAMI, 26.1±5.1; sham, 4.3±1.1; LAMI-D, 2.8±0.8; mean±SEM episodes per sheep, P<0.01). Optical mapping showed spontaneous focal discharges (SFDs) originating from the ischemic/normal-zone border. SFDs were calcium driven, rate dependent, and enhanced by isoproterenol (0.03 µmol/L, from 210±87 to 3816±1450, SFDs per sheep) but suppressed by dantrolene (to 55.8±32.8, SFDs per sheep, mean±SEM). SFDs initiated AF-maintaining reentrant rotors anchored by marked conduction delays at the ischemic/normal-zone border. NOS1 (NO synthase-1) protein expression decreased in ischemic zone myocytes, whereas NADPH (nicotinamide adenine dinucleotide phosphate, reduced form) oxidase and xanthine oxidase enzyme activities and reactive oxygen species (DCF [6-carboxy-2',7'-dichlorodihydrofluorescein diacetate]-fluorescence) increased. CaM (calmodulin) aberrantly increased [3H]ryanodine binding to cardiac RyR2 (ryanodine receptors) in the ischemic zone. Dantrolene restored the physiological binding of CaM to RyR2. Atrial ischemia causes spontaneous AF episodes in sheep, caused by SFDs that initiate reentry. Nitroso-redox imbalance in the ischemic zone is associated with intense reactive oxygen species production and altered RyR2 responses to CaM. Dantrolene administration normalizes the CaM response, prevents LAMI-related SFDs, and AF initiation. These findings provide novel insights into the mechanisms underlying ischemia-related atrial arrhythmias.

Outcomes of atrial arrhythmia radiofrequency catheter ablation in patients with Ebstein's anomaly.

Atrial arrhythmias are common in patients with Ebstein's anomaly (EA) despite cardiac surgical repair and concomitant Maze procedures. We aimed to evaluate the outcome of radiofrequency catheter ablation in this group of patients. All patients with EA and atrial arrhythmias who underwent catheter ablation for atrial arrhythmias between 1/1999 and 1/2016 were included. Atrial arrhythmia recurrence was identified as the primary outcome; secondary outcomes included repeat ablation, need for antiarrhythmic medications after ablation, and death. Predictors of recurrence were sought using univariate analysis. 22 patients (median age 42 years, 54.5% male) were included. Atrial flutter was the most common presenting arrhythmia (n = 14 patients, 63.5%), whereas focal atrial tachycardia (FAT) and atrial fibrillation were identified in 5 (22.7%) and 2 patients (9.1%), respectively, with both atrial flutter/fibrillation evident in a single patient 1 (4.5%). 8 patients (36.4%) had a history of right-sided maze procedures. Cavotricuspid isthmus atrial flutter (CTI-AFl) was the most commonly induced arrhythmia (n = 13, 59.1%), followed by incisional intra-atrial re-entrant tachycardia (IART; n = 4, 18.2%), and FAT (n = 4, 18.2%); 3 patients also underwent left-side ablation with concomitant pulmonary vein isolation (13.6%). 1-year and 5-year atrial arrhythmia recurrence rates were 10.0% and 41.2%, respectively. 7 patients (31.8%) underwent redo ablations, and anti-arrhythmic medication was utilized in 8 patients (36.4%) post-ablation. Neither ablation location nor echocardiographic parameters were found to be predictors of arrhythmia recurrence. Catheter ablation of atrial arrhythmias in patients with EA has a favorable outcome overall with an acceptable recurrence and safety profile; left-sided ablations are rarely necessary. Despite prior Maze and catheter ablation procedures, CTI-AFl and IART recurrences predominate.

Benefits of Atrial Substrate Modification Guided by Electrogram Similarity and Phase Mapping Techniques to Eliminate Rotors and Focal Sources Versus Conventional Defragmentation in Persistent Atrial Fibrillation.

This prospective study compared the efficacy of atrial substrate modification guided by a nonlinear phase mapping technique with that of conventional substrate ablation. The optimal ablation strategy for persistent atrial fibrillation (AF) was unknown. In phase 1 study, we applied a cellular automation technique to simulate the electrical wave propagation to improve the phase mapping algorithm, involving analysis of high-similarity electrogram regions. In addition, we defined rotors and focal AF sources, using the physical parameters of the divergence and curvature forces. In phase 2 study, we enrolled 68 patients with persistent AF undergoing substrate modification into 2 groups, group-1 (n= 34) underwent similarity index (SI) and phase mapping techniques; group-2 (n= 34) received complex fractionated atrial electrogram ablation with commercially available software. Group-1 received real-time waveform similarity measurements in which a phase mapping algorithm was applied to localize the sources. We evaluated the single-procedure freedom from AF. In group-1, we identified an average of 2.6 ± 0.89 SI regions per chamber. These regions involved rotors and focal sources in 65% and 77% of patients in group-1, respectively. Group-1 patients had shorter ablation procedure times, higher termination rates, and significant reduction in AF recurrence compared to group-2 and a trend toward benefit for all atrial arrhythmias. Multivariate analysis showed that substrate mapping using nonlinear similarity and phase mapping was the independent predictor of freedom from AF recurrence (hazard ratio: 0.26; 95% confidence interval: 0.09 to 0.74; p= 0.01). Our study showed that for persistent AF ablation, a specified substrate modification guided by nonlinear phase mapping could eliminate localized re-entry and non-pulmonary focal sources after pulmonary vein isolation.