Comparison of cerebral safety following atrial fibrillation using pulsed field and thermal ablation: Results of the Neurological Assessment Subgroup in the ADVENT Trial.

BACKGROUND: Atrial fibrillation (AF) ablation carries the risk of silent cerebral event (SCE) and silent cerebral lesion (SCL). Though "silent," these may have long-term clinical implications and are challenging to study as post-procedural MRI is not standard-of-care. OBJECTIVE: The neurological assessment subgroup (NAS) of ADVENT compared cerebral effects of pulsed field ablation (PFA) to standard-of-care thermal ablation. METHODS: The NAS included consecutive randomized PFA and thermal ablation patients who received post-procedural brain MRI 12-48 hours post-ablation. Patients with apparent SCE or SCL findings underwent a modified Rankin Scale (mRS) assessment. MRI images were subsequently reviewed by a blinded Brain Imaging Core Laboratory. RESULTS: In total, 77 patients with paroxysmal AF were enrolled at 6 centers; 71 had analyzable scans (34 PFA; 37 thermal ablation). Through individual center review, 6 PFA and 4 thermal scans were identified as SCE/SCL positive, of which, 3 PFA and 0 thermal SCE/SCL findings were confirmed by a blinded core laboratory. MRI findings revealed one patient with 2-4mm SCEs, one patient with a 3mm SCE, and one patient with 2 SCLs (5.5mm and 11mm). All mRS and NIHSS scores were 0 prior to discharge and at 90-day follow-up. There were only two neurological safety events (1 TIA (PFA) and 1 stroke (thermal) in the ADVENT study, neither of which was part of the NAS. CONCLUSIONS: The ADVENT trial provides the first prospective, randomized data on the cerebral impact of PFA and thermal ablation of AF. Incidence of SCE/SCLs following ablation in the NAS was low.

Catheter Ablation as First-Line Therapy in Persistent Atrial Fibrillation: Patient Characteristics and Clinical Outcomes.

BACKGROUND: In patients with persistent atrial fibrillation (PerAF), antiarrhythmic drugs (AADs) are considered a first-line rhythm-control strategy, whereas catheter ablation is a reasonable alternative. OBJECTIVES: This study sought to examine the prevalence, patient characteristics, and clinical outcomes of patients with PerAF who underwent catheter ablation as a first or second-line strategy. METHODS: This multicenter observational study included consecutive patients with PerAF who underwent first-time ablation between January 2020 and September 2021 in 9 medical centers in the United States. Patients were divided into those who underwent ablation as first-line therapy and those who had ablation as second-line therapy. Patient characteristics and clinical outcomes were compared between the groups. RESULTS: A total of 2,083 patients underwent first-time ablation for PerAF. Of these, 1,086 (52%) underwent ablation as a first-line rhythm-control treatment. Compared with patients treated with AADs as first-line therapy, these patients were predominantly male (72.6% vs 68.1%; P = 0.03), with a lower frequency of hypertension (64.0% vs 73.4%; P < 0.001) and heart failure (19.1% vs 30.5%; P < 0.001). During a mean follow-up of 325.9 ± 81.6 days, arrhythmia-free survival was similar between the groups (HR: 1.13; 95% CI: 0.92-1.41); however, patients in the second-line ablation strategy were more likely to continue receiving AAD therapy (41.5% vs 15.9%; P < 0.001). CONCLUSIONS: A first-line ablation strategy for PerAF is prevalent in the United States, particularly in men with fewer comorbidities. More data are needed to identify patients with PerAF who derive benefit from an early intervention strategy.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation.

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society .

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation.

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society (HRS), the Asia Pacific HRS, and the Latin American HRS.

Pulmonary vein narrowing after pulsed field versus thermal ablation.

AIMS: When it occurs, pulmonary vein (PV) stenosis after atrial fibrillation (AF) ablation is associated with significant morbidity. Even mild-to-moderate PV narrowing may have long-term implications. Unlike thermal ablation energies, such as radiofrequency (RF) or cryothermy, pulsed field ablation (PFA) is a non-thermal modality associated with less fibrotic proliferation. Herein, we compared the effects of PFA vs. thermal ablation on PV narrowing after AF ablation. METHODS AND RESULTS: ADVENT was a multi-centre, randomized, single-blind study comparing PFA (pentaspline catheter) with thermal ablation-force-sensing RF or cryoballoon (CB)-to treat drug-refractory paroxysmal AF. Pulmonary vein diameter and aggregate cross-sectional area were obtained by baseline and 3-month imaging. The pre-specified, formally tested, secondary safety endpoint compared a measure of PV narrowing between PFA vs. thermal groups, with superiority defined by posterior probability > 0.975. Among subjects randomized to PFA (n = 305) or thermal ablation (n = 302), 259 PFA and 255 thermal ablation (137 RF and 118 CB) subjects had complete baseline and 3-month PV imaging. No subject had significant (≥70%) PV stenosis. Change in aggregate PV cross-sectional area was less with PFA (-0.9%) than thermal ablation (-12%, posterior probability > 0.999)-primarily driven by the RF sub-cohort (-19.5%) vs. CB sub-cohort (-3.3%). Almost half of all PFA PV diameters did not decrease, but the majority (80%) of RF PVs decreased, regardless of PV anatomic location. CONCLUSION: In this first randomized comparison of PFA vs. thermal ablation, PFA resulted in less PV narrowing-thereby underscoring the qualitatively differential and favourable impact of PFA on PV tissue.

Acute alcohol exposure and electrocardiographic changes: Finding from the HOLIDAY trial.

BACKGROUND: Alcohol consumption is associated with a higher increased risk of atrial fibrillation (AF), but the acute effects on cardiac electrophysiology in humans remain poorly understood. The HOw ALcohol InDuces Atrial TachYarrhythmias (HOLIDAY) Trial revealed that alcohol shortened pulmonary vein atrial effective refractory periods, but more global electrophysiologic changes gleaned from the surface ECG have not yet been reported. METHODS: This was a secondary analysis of the HOLIDAY Trial. During AF ablation procedures, 100 adults were randomized to intravenous alcohol titrated to 0.08% blood alcohol concentration versus a volume and osmolarity-matched, masked, placebo. Intervals measured from 12­lead ECGs were compared between pre infusion and at infusion steady state (20 min). RESULTS: The average age was 60 years and 11% were female. No significant differences in the P-wave duration, PR, QRS or QT intervals, were present between alcohol and placebo arms. However, infusion of alcohol was associated with a statistically significant relative shortening of the JT interval (r: -14.73, p = 0.048) after multivariable adjustment. CONCLUSION: Acute exposure to alcohol was associated with a relative reduction in the JT interval, reflecting shortening of ventricular repolarization. These acute changes may reflect a more global shortening of refractoriness, suggesting immediate proarrhythmic effects pertinent to the atria and ventricles.

Frequent Premature Atrial Contractions Lead to Adverse Atrial Remodeling and Atrial Fibrillation in a Swine Model.

BACKGROUND: Frequent premature atrial complexes (PACs) are associated with future incident atrial fibrillation (AF), but whether PACs contribute to development of AF through adverse atrial remodeling has not been studied. This study aimed to explore the effect of frequent PACs from different sites on atrial remodeling in a swine model. METHODS: Forty swine underwent baseline electrophysiologic studies and echocardiography followed by pacemaker implantations and paced PACs (50% burden) at 250-ms coupling intervals for 16 weeks in 4 groups: (1) lateral left atrium (LA) PACs by the coronary sinus (Lat-PAC; n=10), (2) interatrial septal PACs (Sep-PAC; n=10), (3) regular LA pacing at 130 beats/min (Reg-130; n=10), and (4) controls without PACs (n=10). At the final study, repeat studies were performed, followed by tissue histology and molecular analyses focusing on fibrotic pathways. RESULTS: Lat-PACs were associated with a longer P-wave duration (93.0±9.0 versus 74.2±8.2 and 58.8±7.6 ms; P<0.001) and greater echocardiographic mechanical dyssynchrony (57.5±11.6 versus 35.7±13.0 and 24.4±11.1 ms; P<0.001) compared with Sep-PACs and controls, respectively. After 16 weeks, Lat-PACs led to slower LA conduction velocity (1.1±0.2 versus 1.3±0.2 [Sep-PAC] versus 1.3±0.1 [Reg-130] versus 1.5±0.2 [controls] m/s; P<0.001) without significant change in atrial ERP. The Lat-PAC group had a significantly increased percentage of LA fibrosis and upregulated levels of extracellular matrix proteins (lysyl oxidase and collagen 1 and 8), as well as TGF-ß1 (transforming growth factor-ß1) signaling proteins (latent and monomer TGF-ß1 and phosphorylation/total ratio of SMAD2/3; P<0.05). The Lat-PAC group had the longest inducible AF duration (terminal to baseline: 131 [interquartile range 30, 192] seconds versus 16 [6, 26] seconds [Sep-PAC] versus 22 [11, 64] seconds [Reg-130] versus -1 [-16, 7] seconds [controls]; P<0.001). CONCLUSIONS: In this swine model, frequent PACs resulted in adverse atrial structural remodeling with a heightened propensity to AF. PACs originating from the lateral LA produced greater atrial remodeling and longer induced AF duration than the septal-origin PACs. These data provide evidence that frequent PACs can cause adverse atrial remodeling as well as AF, and that the location of ectopic PACs may be clinically meaningful.

Optimal Annotation of Local Activation Time in Ventricular Tachycardia Substrate Mapping.

BACKGROUND: Accurate annotation of electrogram local activation time (LAT) is critical to the functional assessment of ventricular tachycardia (VT) substrate. Contemporary methods of annotation include: 1) earliest bipolar electrogram (LATearliest); 2) peak bipolar electrogram (LATpeak); 3) latest bipolar electrogram (LATlatest); and 4) steepest unipolar -dV/dt (LAT-dV/dt). However, no direct comparison of these methods has been performed in a large dataset, and it is unclear which provides the optimal functional analysis of the VT substrate. OBJECTIVES: This study sought to investigate the optimal method of LAT annotation during VT substrate mapping. METHODS: Patients with high-density VT substrate maps and a defined critical site for VT re-entry were included. All electrograms were annotated using 5 different methods: LATearliest, LATpeak, LATlatest, LAT-dV/dt, and the novel steepest unipolar -dV/dt using a dynamic window of interest (LATDWOI). Electrograms were also tagged as either late potentials and/or fractionated signals. Maps, utilizing each annotation method, were then compared in their ability to identify critical sites using deceleration zones. RESULTS: Fifty cases were identified with 1,.813 ± 811 points per map. Using LATlatest, a deceleration zone was present at the critical site in 100% of cases. There was no significant difference with LATearliest (100%) or LATpeak (100%). However, this number decreased to 54% using LAT-dV/dt and 76% for LATDWOI. Using LAT-dV/dt, only 33% of late potentials were correctly annotated, with the larger far field signals often annotated preferentially. CONCLUSIONS: Annotation with LAT-dV/dt and LATDWOI are suboptimal in VT substrate mapping. We propose that LATlatest should be the gold standard annotation method, as this allows identification of critical sites and is most suited to automation.

Atrioesophageal Fistula Rates Before and After Adoption of Active Esophageal Cooling During Atrial Fibrillation Ablation.

BACKGROUND: Active esophageal cooling reduces the incidence of endoscopically identified severe esophageal lesions during radiofrequency (RF) catheter ablation of the left atrium for the treatment of atrial fibrillation. A formal analysis of the atrioesophageal fistula (AEF) rate with active esophageal cooling has not previously been performed. OBJECTIVES: The authors aimed to compare AEF rates before and after the adoption of active esophageal cooling. METHODS: This institutional review board (IRB)-approved study was a prospective analysis of retrospective data, designed before collecting and analyzing the real-world data. The number of AEFs occurring in equivalent time frames before and after adoption of cooling using a dedicated esophageal cooling device (ensoETM, Attune Medical) were quantified across 25 prespecified hospital systems. AEF rates were then compared using generalized estimating equations robust to cluster correlation. RESULTS: A total of 14,224 patients received active esophageal cooling during RF ablation across the 25 hospital systems, which included a total of 30 separate hospitals. In the time frames before adoption of active cooling, a total of 10,962 patients received primarily luminal esophageal temperature (LET) monitoring during their RF ablations. In the preadoption cohort, a total of 16 AEFs occurred, for an AEF rate of 0.146%, in line with other published estimates for procedures using LET monitoring. In the postadoption cohort, no AEFs were found in the prespecified sites, yielding an AEF rate of 0% (P < 0.0001). CONCLUSIONS: Adoption of active esophageal cooling during RF ablation of the left atrium for the treatment of atrial fibrillation was associated with a significant reduction in AEF rate.

Identification of supraventricular tachycardia mechanisms with surface electrocardiograms using a convolutional neural network.

Background: It remains difficult to definitively distinguish supraventricular tachycardia (SVT) mechanisms using a 12-lead electrocardiogram (ECG) alone. Machine learning may identify visually imperceptible changes on 12-lead ECGs and may improve ability to determine SVT mechanisms. Objective: We sought to develop a convolutional neural network (CNN) that identifies the SVT mechanism according to the gold standard of SVT ablation and to compare CNN performance against experienced electrophysiologists among patients with atrioventricular nodal re-entrant tachycardia (AVNRT), atrioventricular reciprocating tachycardia (AVRT), and atrial tachycardia (AT). Methods: All patients with 12-lead surface ECG during sinus rhythm and SVT and had successful SVT ablation from 2013 to 2020 were included. A CNN was trained using data from 1505 surface ECGs that were split into 1287 training and 218 test ECG datasets. We compared the CNN performance against independent adjudication by 2 experienced cardiac electrophysiologists on the test dataset. Results: Our dataset comprised 1505 ECGs (368 AVNRT, 304 AVRT, 95 AT, and 738 sinus rhythm) from 725 patients. The CNN areas under the receiver-operating characteristic curve for AVNRT, AVRT, and AT were 0.909, 0.867, and 0.817, respectively. When fixing the specificity of the CNN to the electrophysiologist adjudicators' specificity, the CNN identified all SVT classes with higher sensitivity: (1) AVNRT (91.7% vs 65.9%), (2) AVRT (78.4% vs 63.6%), and (3) AT (61.5% vs 50.0%). Conclusion: A CNN can be trained to differentiate SVT mechanisms from surface 12-lead ECGs with high overall performance, achieving similar performance to experienced electrophysiologists at fixed specificities.

Pulsed Field or Conventional Thermal Ablation for Paroxysmal Atrial Fibrillation.

BACKGROUND: Catheter-based pulmonary vein isolation is an effective treatment for paroxysmal atrial fibrillation. Pulsed field ablation, which delivers microsecond high-voltage electrical fields, may limit damage to tissues outside the myocardium. The efficacy and safety of pulsed field ablation as compared with conventional thermal ablation are not known. METHODS: In this randomized, single-blind, noninferiority trial, we assigned patients with drug-refractory paroxysmal atrial fibrillation in a 1:1 ratio to undergo pulsed field ablation or conventional radiofrequency or cryoballoon ablation. The primary efficacy end point was freedom from a composite of initial procedural failure, documented atrial tachyarrhythmia after a 3-month blanking period, antiarrhythmic drug use, cardioversion, or repeat ablation. The primary safety end point included acute and chronic device- and procedure-related serious adverse events. RESULTS: A total of 305 patients were assigned to undergo pulsed field ablation, and 302 were assigned to undergo thermal ablation. At 1 year, the primary efficacy end point was met (i.e., no events occurred) in 204 patients (estimated probability, 73.3%) who underwent pulsed field ablation and 194 patients (estimated probability, 71.3%) who underwent thermal ablation (between-group difference, 2.0 percentage points; 95% Bayesian credible interval, -5.2 to 9.2; posterior probability of noninferiority, >0.999). Primary safety end-point events occurred in 6 patients (estimated incidence, 2.1%) who underwent pulsed field ablation and 4 patients (estimated incidence, 1.5%) who underwent thermal ablation (between-group difference, 0.6 percentage points; 95% Bayesian credible interval, -1.5 to 2.8; posterior probability of noninferiority, >0.999). CONCLUSIONS: Among patients with paroxysmal atrial fibrillation receiving a catheter-based therapy, pulsed field ablation was noninferior to conventional thermal ablation with respect to freedom from a composite of initial procedural failure, documented atrial tachyarrhythmia after a 3-month blanking period, antiarrhythmic drug use, cardioversion, or repeat ablation and with respect to device- and procedure-related serious adverse events at 1 year. (Funded by Farapulse-Boston Scientific; ADVENT ClinicalTrials.gov number, NCT04612244.).

A Randomized Trial of High vs Standard Power Radiofrequency Ablation for Pulmonary Vein Isolation: SHORT-AF.

BACKGROUND: High-power, short duration (HPSD) radiofrequency ablation (RFA) is a commonly used strategy for pulmonary vein isolation (PVI). OBJECTIVES: This study sought to compare HPSD with standard power, standard duration (SPSD) RFA in patients undergoing PVI. METHODS: Patients with paroxysmal or persistent (<1 year) atrial fibrillation (AF) were randomized to HPSD (50 W) or SPSD (25-30 W) RFA to achieve PVI. Outcomes assessed included time to achieve PVI (primary), left atrial dwell time, total procedure time, first-pass isolation, PV reconnection with adenosine, procedure complications including asymptomatic cerebral emboli (ACE), and freedom from atrial arrhythmias. RESULTS: Sixty patients (median age 66 years; 75% male) with paroxysmal (57%) or persistent (43%) AF were randomized to HPSD (n = 29) or SPSD (n = 31). Median time to achieve PVI was shorter with HPSD vs SPSD (87 minutes vs 126 minutes; P = 0.003), as was left atrial dwell time (157 minutes vs 180 minutes; P = 0.04). There were no differences in first-pass isolation (79% vs 76%; P = 0.65) or PV reconnection with adenosine (12% vs 20%; P = 0.26) between groups. At 12 months, recurrent atrial arrhythmias occurred less in the HPSD group compared with the SPSD group (n = 3 of 29 [10%] vs n = 11 of 31 [35%]; HR: 0.26; P = 0.027). There was a trend toward more ACE with HPSD RFA (40% HPSD vs 17% SPSD; P = 0.053). CONCLUSIONS: In patients undergoing AF ablation, HPSD compared with SPSD RFA results in shorter time to achieve PVI, greater freedom from AF at 12 months, and a trend toward increased ACE.

A randomized controlled trial of pulsed field ablation versus standard-of-care ablation for paroxysmal atrial fibrillation: The ADVENT trial rationale and design.

Background: Pulmonary vein isolation (PVI) is an effective treatment for paroxysmal atrial fibrillation (PAF). However, potential complications can occur due to the propagation of thermal energy into nontarget tissues adjacent to the targeted myocardium. Pulsed field ablation (PFA) is a novel ablation modality with the potential for preferential myocardial tissue ablation to minimize damage to collateral cardiac structures. A multielectrode pentaspline catheter has demonstrated safety and efficacy in treating PAF in single-arm, first-in-human studies. Objective: The study sought to perform a randomized clinical trial to directly compare this PFA catheter with conventional ablation-either radiofrequency or cryoballoon ablation. Methods: The ADVENT (Randomized Controlled Trial for Pulsed Field Ablation versus Standard of Care Ablation for Paroxysmal Atrial Fibrillation) trial is a multicenter, prospective, single-blind, randomized controlled trial to compare PVI using PFA vs conventional thermal ablation for drug-resistant PAF-with each site employing either (but not both) cryoballoon or radiofrequency ablation as a control condition. The sample size is adaptively determined based on Bayesian statistical methods. All patients will undergo PVI, and be followed for 12 months. Results: The primary effectiveness endpoint is a composite of acute procedural success and freedom from any documented atrial arrhythmia recurrence, repeat ablation, or use of antiarrhythmic drugs after a 3-month postablation blanking period. The primary safety endpoint is a composite of defined acute and chronic device- and procedure-related serious adverse events. Both primary endpoints will be evaluated for noninferiority of the novel PFA system compared with standard-of-care thermal ablation. Conclusions: By providing objective, comparative data, this study aims to scientifically determine whether the pentaspline PFA catheter is safe and effective for PVI ablation to treat drug-resistant PAF.

Iatrogenic Atrioventricular Block.

Iatrogenic atrioventricular (AV) block can occur in the context of cardiac surgery, percutaneous transcatheter, or electrophysiologic procedures. In cardiac surgery, patients undergoing aortic and/or mitral valve surgery are at the highest risk for developing perioperative AV block requiring permanent pacemaker implantation. Similarly, patients undergoing transcatheter aortic valve replacement are also at increased risk for developing AV block. Electrophysiologic procedures, including catheter ablation of AV nodal re-entrant tachycardia, septal accessory pathways, para-Hisian atrial tachycardia, or premature ventricular complexes, are also associated with risk of AV conduction system injury. In this article, we summarize the common causes for iatrogenic AV block, predictors for AV block, and general management considerations.