Persistent Atrial Fibrillation Ablation: Where Do We Go From Here?

Dual-energy lattice-tip ablation system for persistent atrial fibrillation: a randomized trial

Clinical outcomes of catheter ablation for atrial fibrillation (AF) are suboptimal due, in part, to challenges in achieving durable lesions. Although focal point-by-point ablation allows for the creation of any required lesion set, this strategy necessitates the generation of contiguous lesions without gaps. A large-tip catheter, capable of creating wide-footprint ablation lesions, may increase ablation effectiveness and efficiency. In a randomized, single-blind, non-inferiority trial, 420 patients with persistent AF underwent ablation using a large-tip catheter with dual pulsed field and radiofrequency energies versus ablation using a conventional radiofrequency ablation system. The primary composite effectiveness endpoint was evaluated through 1 year and included freedom from acute procedural failure and repeat ablation at any time, plus arrhythmia recurrence, drug initiation or escalation or cardioversion after a 3-month blanking period. The primary safety endpoint was freedom from a composite of serious procedure-related or device-related adverse events. The primary effectiveness endpoint was observed for 73.8% and 65.8% of patients in the investigational and control arms, respectively (P < 0.0001 for non-inferiority). Major procedural or device-related complications occurred in three patients in the investigational arm and in two patients in the control arm (P < 0.0001 for non-inferiority). In a secondary analysis, procedural times were shorter in the investigational arm as compared to the control arm (P < 0.0001). These results demonstrate non-inferior safety and effectiveness of the dual-energy catheter for the treatment of persistent AF. Future large-scale studies are needed to gather real-world evidence on the impact of the focal dual-energy lattice catheter on the broader population of patients with AF. ClinicalTrials.gov identifier: NCT05120193 .

Predictors and timeline of spontaneous conversion to normal sinus rhythm: A single center retrospective cohort study of patients with symptomatic atrial fibrillation

INTRODUCTION

Annual healthcare expenditures associated with atrial fibrillation (AF) in the United States (US) continue to grow as more symptomatic patients present to emergency departments (ED). Predictors of spontaneous conversion to normal sinus rhythm (ScNSR) remain poorly understood, as well as the timeline of ScNSR remains unclear. We sought to 1) to assess the association of key demographics, anthropometric, and clinical factors to ScNSR and 2) to evaluate the timeline of ScNSR, and 3) determine clinical predictors of ScNSR.

METHODS

This single center, retrospective cohort study analyzed patients aged ≥18 years with symptomatic AF as diagnosed and evaluated through the ED of a rural tertiary care center in West Virginia from September 2015 to December 2018.

RESULTS

Our cohort consisted of 375 AF patients (mean age 65 years, 54% male). A total of 177 patients attained ScNSR either in the ED or after hospital admission with a mean conversion time of 14.7 h (±12). Onset of symptoms <24 hrs has strong positive association to ScNSR 3.97 (95% CI: 2.24-7.05; p < 0.0001). Male gender 0.55 (95% CI: 0.35-0.85; p = 0.007) and hypertension 0.48 (95% CI: 0.31-0.76; p = 0.002), showed a strong negative association to ScNSR. Of the patients that converted spontaneously (177), the majority, 136 (76.8%) achieved ScNSR within 24 h of ED triage without use of electrical or chemical cardioversion.

CONCLUSION

Most patients with AF in the ED converted spontaneously to sinus rhythm within the first 24 h which underscores the importance of earlier watchful waiting over interventions to achieve normal sinus rhythm (NSR).

A Predictive and an Optimization Mathematical Model for Device Design in Cardiac Pulsed Field Ablation Using Design of Experiments

Cardiac catheter ablation (CCA) is a common method used to correct cardiac arrhythmia. Pulsed Field Ablation (PFA) is a recently-adapted CCA technology whose ablation is dependent on electrode and waveform parameters (factors). In this work, the use of the Design of Experiments (DoE) methodology is investigated for the design and optimization of a PFA device. The effects of the four factors (input voltage, electrode spacing, electrode width, and on-time) and their interactions are analyzed. An empirical model is formed to predict and optimize the ablation size responses. Based on the ranges tested, the significant factors were the input voltage, the electrode spacing, and the on time, which is in line with the literature. Two-factor interactions were found to be significant and need to be considered in the model. The resulting empirical model was found to predict ablation sizes with less than 2.1% error in the measured area and was used for optimization. The findings and the strong predictive model developed highlight that the DoE approach can be used to help determine PFA device design, to optimize for certain ablation zone sizes, and to help inform device design to tackle specific cardiac arrhythmias.

Radiofrequency catheter ablation of atrial fibrillation: A review of techniques

Ablation of atrial fibrillation is a key area of current research. A multitude of techniques have been tested, some of which are poorly evidenced and not recommended in routine clinical practice whilst others are more promising. Additionally, a plethora of issues exist when researching ablation techniques, from control arm ablation strategy to the relevance of outcome measures. In this review article, we discuss these issues in the context of the current evidence base.

Combined Minimally Invasive Surgical and Percutaneous Catheter Ablation of Atrial Fibrillation: JACC Review Topic of the Week

Hybrid ablation is a novel therapy in the invasive management of patients with atrial fibrillation (AF) which combines minimally invasive surgical and percutaneous catheter-based techniques. The evidence is mainly based on observational studies from experienced centers, with success rates of approximately 70% and risks that are 2.0-fold to 3.6-fold higher than catheter-based ablation. Hybrid ablation is offered typically to patients with persistent or longstanding persistent AF which, by design, requires 2 procedures (epicardial surgical and endocardial catheter-based ablation). One randomized trial demonstrated that hybrid ablation was more effective than catheter-based ablation, but with higher complication rates. The incidence of the most serious complications has decreased in contemporary studies of hybrid ablation. At present, hybrid ablation should be performed by experienced centers on selected patients with persistent or longstanding persistent AF. Additional randomized trials are needed to define the risks, benefits, and cost effectiveness of hybrid ablation to identify its most appropriate application in clinical practice.

Comparing the efficacy of catheter ablation strategies for persistent atrial fibrillation: a Bayesian analysis of randomized controlled trials

BACKGROUND

Catheter ablation has been recommended as the first-line treatment option for selected patients with atrial fibrillation (AF). However, a widely accepted ablation strategy for persistent AF (perAF) has not yet been established. The benefits of ablation strategies are not conclusive for perAF. There is an urgent need to systematically analyze the results of previous studies and rank these treatment strategies to guide clinical practice.

METHODS

Randomized controlled trials (RCTs) on ablation for perAF were included. The primary outcome was recurrence of atrial tachyarrhythmia (AT) after a single ablation procedure. A Bayesian random-effects network meta-analysis model was fitted.

RESULTS

Twenty-three studies were included in the analysis. A total of 3394 patients and 22 ablation strategies were found in the involved studies. The ablation strategy of pulmonary vein isolation (PVI) + electrical box isolation of the left atrial posterior wall (PBOX) + non-PV trigger ablation (NPV) showed the best treatment effect in terms of the primary outcome. The individualized ablation strategies of mapping and ablation combined with PVI, such as PVI + rotors, PVI + dispersion areas, and PVI + low voltage zone (LVZ) also showed a better ablation effect in perAF.

CONCLUSIONS

PVI ablation is a widely used strategy in perAF and is recognized as a cornerstone procedure for perAF. The PVI + PBOX + NPV strategy showed the highest rank in our analysis. Mapping and ablation strategies that could provide individualized substrate modification also showed a better rank in our analysis and are believed to be a promising direction for the treatment of perAF.

Recent clinical trials in atrial fibrillation

PURPOSE OF REVIEW

Management of atrial fibrillation can be overwhelming with the amount of information and treatment options available today. This review discusses landmark and other clinically relevant trials published in the last 18 months.

RECENT FINDINGS

There have been several recent key clinical trials and subanalyses in the field of atrial fibrillation. Early rhythm control with ablation or antiarrhythmic medications has upended the previous practice of rate control for patients with atrial fibrillation. Vein of Marshall alcohol ablation in combination with endocardial mitral annular ablation and a hybrid epicardial/endocardial approach has shown promising results in the fight against persistent atrial fibrillation. Early ablation with cryoballoon therapy vs. antiarrhythmic therapy gives further evidence for early ablation in patients with symptomatic paroxysmal atrial fibrillation.

SUMMARY

The rapid development in technology and medications to treat atrial fibrillation, prevent stroke and improve quality of life for patients has created a vast amount of information for physicians to process. The present review will focus on the recent (within 2 years) clinical trials in atrial fibrillation and the impact they may have on your practice.

[Artificial Intelligence and teleradiology in cardiovascular imaging by CT-Scan and MRI]

Cardiac CT-Scan and cardiac magnetic resonance imaging (MRI) are two booming cardiac imaging modalities especially in chest pain screening for CT-Scan and in surveillance of patients with known coronary artery disease for MRI. Artificial Intelligence is already of great help in radiologic diagnosis and its use should widen in the next few years. Teleradiology allows remote interpretation of all radiology exams and should develop in cardiac imaging. Expert radiology diagnosis centers should develop gathering cardiologists and radiologists with great experience in the field of cardiac imaging interpretation. Peripheral acquisition radiology centers would be disseminated all across the country without a need for a local expert and would send their images to the expert center for interpretation. The expert center would be the middle of this spider web, sending back the report and the selected images to the peripheral center, allowing optimal care for all patients nationwide. Artificial Intelligence would be a major asset of these expert centers, improving through the years. This operating mode would allow the onset of systematic screening for coronary artery disease in the global population and the surveillance of known coronary artery disease treated patients.

Atrial Remodeling in Atrial Fibrillation. Comorbidities and Markers of Disease Progression Predict Catheter Ablation Outcome

Atrial fibrillation is the most common supraventricular arrhythmia affecting an increasing proportion of the population in which mainstream therapy, i.e. catheter ablation, provides freedom from arrhythmia in only a limited number of patients. Understanding the mechanism is key in order to find more effective therapies and to improve patient selection. In this review, the structural and electrophysiological changes of the atrial musculature that constitute atrial remodeling in atrial fibrillaton and how risk factors and markers of disease progression can predict catheter ablation outcome will be discussed in detail.

Circular RNA mmu_circ_0005019 inhibits fibrosis of cardiac fibroblasts and reverses electrical remodeling of cardiomyocytes

BACKGROUND

Circular RNA (circRNA) have been reported to play important roles in cardiovascular diseases including myocardial infarction and heart failure. However, the role of circRNA in atrial fibrillation (AF) has rarely been investigated. We recently found a circRNA hsa_circ_0099734 was significantly differentially expressed in the AF patients atrial tissues compared to paired control. We aim to investigate the functional role and molecular mechanisms of mmu_circ_0005019 which is the homologous circRNA in mice of hsa_circ_0099734 in AF.

METHODS

In order to investigate the effect of mmu_circ_0005019 on the proliferation, migration, differentiation into myofibroblasts and expression of collagen of cardiac fibroblasts, and the effect of mmu_circ_0005019 on the apoptosis and expression of Ito, INA and SK3 of cardiomyocytes, gain- and loss-of-function of cell models were established in mice cardiac fibroblasts and HL-1 atrial myocytes. Dual-luciferase reporter assays and RIP were performed to verify the binding effects between mmu_circ_0005019 and its target microRNA (miRNA).

RESULTS

In cardiac fibroblasts, mmu_circ_0005019 showed inhibitory effects on cell proliferation and migration. In cardiomyocytes, overexpression of mmu_circ_0005019 promoted Kcnd1, Scn5a and Kcnn3 expression. Knockdown of mmu_circ_0005019 inhibited the expression of Kcnd1, Kcnd3, Scn5a and Kcnn3. Mechanistically, mmu_circ_0005019 exerted biological functions by acting as a miR-499-5p sponge to regulate the expression of its target gene Kcnn3.

CONCLUSIONS

Our findings highlight mmu_circ_0005019 played a protective role in AF development and might serve as an attractive candidate target for AF treatment.

Differences in Healthcare Use Between Patients With Persistent and Paroxysmal Atrial Fibrillation Undergoing Catheter-Based Atrial Fibrillation Ablation: A Population-Based Cohort Study From Ontario, Canada

Background Patients with persistent atrial fibrillation (AF) undergoing catheter-based AF ablation have lower success rates than those with paroxysmal AF. We compared healthcare use and clinical outcomes between patients according to their AF subtypes. Methods and Results Consecutive patients undergoing AF ablation were prospectively identified from a population-based registry in Ontario, Canada. Via linkage with administrative databases, we performed a retrospective analysis comparing the following outcomes between patients with persistent and paroxysmal AF: healthcare use (defined as AF-related hospitalizations/emergency room visits), periprocedural complications, and mortality. Multivariable Poisson modeling was performed to compare the rates of AF-related and all-cause hospitalizations/emergency room visits in the year before versus after ablation. Between April 2012 and March 2016, there were 3768 consecutive patients who underwent first-time AF ablation, of whom 1040 (27.6%) had persistent AF. The mean follow-up was 1329 days. Patients with persistent AF had higher risk of AF-related hospitalization/emergency room visits (hazard ratio [HR], 1.21; 95% CI, 1.09-1.34), mortality (HR, 1.74; 95% CI, 1.15-2.63), and periprocedural complications (odds ratio, 1.36; 95% CI, 1.02-1.75) than those with paroxysmal AF. In the overall cohort, there was a 48% reduction in the rate of AF-related hospitalization/emergency room visits in the year after versus before ablation (rate ratio [RR], 0.52; 95% CI, 0.48-0.56). This reduction was observed for patients with paroxysmal (RR, 0.45; 95% CI, 0.41-0.50) and persistent (RR, 0.74; 95% CI, 0.63-0.87) AF. Conclusions Although patients with persistent AF had higher risk of adverse outcomes than those with paroxysmal AF, ablation was associated with a favorable reduction in downstream AF-related healthcare use, irrespective of AF type.

Pulmonary vein reconnection following cryo-ablation: Mind the "Gap" in the carinae and the left atrial appendage ridge

Pulmonary vein (PV) isolation (PVI) remains cornerstone to ablation of atrial fibrillation (AF). For effective and durable PVI and thus fewer AF recurrences, lesion gaps in transmurality and contiguity responsible for PV reconnection (PVR) could only be addressed when one is cognizant of the potential location and sites where these lesion characteristics may be more prevalent and responsible for PVR. In the case of RF ablation, newer technologies incorporating contact force, time and power with automated monitoring of lesion formation, paying attention to difficult areas (carinae, left superior PV-LAA ridge, right inferior PV) and measuring inter-lesion distance may provide the tools to reduce PVR. On the other hand, the improved thermodynamic characteristics of the latest generation of cryoballloons and operator dexterity to achieve better PV occlusion, may be crucial determinants towards the direction of reduced PVR. Whether newer visualization tools, more vigilant testing during the index ablation procedure in these particular regions, prolonging or adding cryothermic applications, waiting longer to test for entrance and exit block, and/or use of provocative drug testing (isoproterenol/adenosine challenge) might help prevent future PVRs awaits further studies.