Temporal trends in safety and complication rates of catheter ablation for atrial fibrillation

Chinese guidelines for the diagnosis and management of atrial fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, significantly impacting patients' quality of life and increasing the risk of death, stroke, heart failure, and dementia. Over the past two decades, there have been significant breakthroughs in AF risk prediction and screening, stroke prevention, rhythm control, catheter ablation, and integrated management. During this period, the scale, quality, and experience of AF management in China have greatly improved, providing a solid foundation for the development of the guidelines for the diagnosis and management of AF. To further promote standardized AF management, and apply new technologies and concepts to clinical practice timely and fully, the Chinese Society of Cardiology of Chinese Medical Association and the Heart Rhythm Committee of Chinese Society of Biomedical Engineering jointly developed the Chinese Guidelines for the Diagnosis and Management of Atrial Fibrillation. The guidelines comprehensively elaborated on various aspects of AF management and proposed the CHA2DS2‑VASc‑60 stroke risk score based on the characteristics of the Asian AF population. The guidelines also reevaluated the clinical application of AF screening, emphasized the significance of early rhythm control, and highlighted the central role of catheter ablation in rhythm control.

Using computed tomogram atrial myocardial thickness maps in high-power short-duration radiofrequency pulmonary vein isolation: UTMOST AF

Background

High-power short-duration (HPSD) ablation creates wide, shallow lesions using radiofrequency (RF) heating. It is uncertain if adjusting RF energy based on atrial wall thickness provides extra benefits. We studied the safety and effectiveness of tailored HPSD energy based on left atrial (LA) wall thickness (LAWT) for circumferential pulmonary vein isolation (CPVI) in patients with paroxysmal atrial fibrillation (PAF).

Methods

We enrolled 212 patients (68.4% male, mean age: 59.5 ± 11.0 years) and randomly assigned them to two groups: LAWT-guided CPVI (WT, n = 108) and conventional CPVI (control, n = 104). Both groups used an open irrigated-tip deflectable catheter to apply 50 W for 10 s to the posterior LA, while controls used 60 W for 15 s on other LA regions. RF delivery time in WT was titrated (15 s at LAWT > 2.1 mm, 13 s at 1.4-2.1 mm, and 11 s at <1.4 mm) according to the computed tomogram-myocardial thickness color map.

Results

After a mean follow-up of 13.4 ± 7.0 months, the WT and control groups showed no significant difference regarding clinical recurrence rate (13.9% vs. 5.8%, respectively; p = .061) and major complication rate (4.6% vs. 3.8%, respectively; p > .999). The total procedure time, cardioversion rate, and post-procedural AAD prescription rates did not significantly differ between the groups.

Conclusions

The LAWT-guided energy titration strategy did not result in improved procedural safety and efficacy compared to the conventional 50-60 W-HPSD CPVI in patients with PAF.

Pulsed field versus cryoballoon ablation for atrial fibrillation: a real-world observational study on procedural outcomes and efficacy

INTRODUCTION

Atrial fibrillation often necessitates catheter ablation when antiarrhythmic drug therapy fails. Single-shot technologies using thermal energy, such as cryoballoon ablation, are commonly used, but pulsed field ablation (PFA), an innovative non-thermal ablation technique, is a potential alternative. This retrospective observational study aimed to compare the safety and efficacy of cryoballoon ablation and PFA in patients undergoing their first pulmonary vein isolation (PVI) procedure for atrial fibrillation treatment.

METHODS

We utilised real-world data from patients who underwent PVI using cryoballoon ablation or PFA. The primary outcome encompassed procedural complications, including phrenic nerve palsy, cardiac tamponade, thromboembolic complications, bleeding complications and mortality. Secondary outcomes were procedural characteristics including procedure duration, length of hospital admission, and re-do ablation rates within 6 months.

RESULTS

A total of 1714 procedures were analysed: 1241 in the cryoballoon group and 473 in the PFA group. Gender distribution (p = 0.03) and estimated glomerular filtration rate (p = 0.01) differed significantly. With regard to the primary outcome, the cryoballoon group demonstrated a higher incidence of phrenic nerve palsy compared with the PFA group (15 vs 0; p = 0.02). The procedure duration was shorter in the PFA group, even after adjusting for baseline characteristics (95.0 vs 74.0 min; p < 0.001). After adjustment for baseline characteristics, admission duration differed between the groups as well (p = 0.04).

CONCLUSION

The study results supported the safety and efficacy of PFA over cryoballoon ablation for PVI, highlighting advantages such as shorter procedure duration and absence of phrenic nerve palsy.

Chinese Guidelines for the Diagnosis and Management of Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, significantly impacting patients' quality of life and increasing the risk of death, stroke, heart failure, and dementia. Over the past two decades, there have been significant breakthroughs in AF risk prediction and screening, stroke prevention, rhythm control, catheter ablation, and integrated management. During this period, the scale, quality, and experience of AF management in China have greatly improved, providing a solid foundation for the development of guidelines for the diagnosis and management of AF. To further promote standardized AF management, and apply new technologies and concepts to clinical practice in a timely and comprehensive manner, the Chinese Society of Cardiology of the Chinese Medical Association and the Heart Rhythm Committee of the Chinese Society of Biomedical Engineering have jointly developed the Chinese Guidelines for the Diagnosis and Management of Atrial Fibrillation. The guidelines have comprehensively elaborated on various aspects of AF management and proposed the CHA2DS2-VASc-60 stroke risk score based on the characteristics of AF in the Asian population. The guidelines have also reevaluated the clinical application of AF screening, emphasized the significance of early rhythm control, and highlighted the central role of catheter ablation in rhythm control.

Cardiac magnetic resonance for early atrial lesion visualization post atrial fibrillation radiofrequency catheter ablation

BACKGROUND

Incomplete atrial lesions resulting in pulmonary vein-left atrium reconnection after pulmonary vein antrum isolation (PVAI), are related to atrial fibrillation (AF) recurrence. Unfortunately, during the PVAI procedure, fluoroscopy and electroanatomic mapping cannot accurately determine the location and size of the ablation lesions in the atrial wall and this can result in incomplete PVAI lesions (PVAI-L) after radiofrequency catheter ablation (RFCA).

AIM

We seek to evaluate whether cardiac magnetic resonance (CMR), immediately after RFCA of AF, can identify PVAI-L by characterizing the left atrial tissue.

METHODS

Ten patients (63.1 ± 5.7 years old, 80% male) receiving a RFCA for paroxysmal AF underwent a CMR before (<1 week) and after (<1 h) the PVAI. Two-dimensional dark-blood T2-weighted short tau inversion recovery (DB-STIR), Three-dimensional inversion-recovery prepared long inversion time (3D-TWILITE) and three-dimensional late gadolinium enhancement (3D-LGE) images were performed to visualize PVAI-L.

RESULTS

The PVAI-L was visible in 10 patients (100%) using 3D-TWILITE and 3D-LGE. Conversely, On DB-STIR, the ablation core of the PAVI-L could not be identified because of a diffuse high signal of the atrial wall post-PVAI. Microvascular obstruction was identified in 7 (70%) patients using 3D-LGE.

CONCLUSION

CMR can visualize PVAI-L immediately after the RFCA of AF even without the use of contrast agents. Future studies are needed to understand if the use of CMR for PVAI-L detection after RFCA can improve the results of ablation procedures.

50-W vs 40-W During High-Power Short-Duration Ablation for Paroxysmal Atrial Fibrillation: A Multicenter Prospective Study

BACKGROUND

High-power short-duration (HPSD) radiofrequency ablation of atrial fibrillation (AF) increases first-pass pulmonary vein isolation (PVI) and freedom from atrial arrhythmias while decreasing procedural time. However, the optimal power setting in terms of safety and efficacy has not been determined.

OBJECTIVES

This study compared the procedural characteristics and clinical outcomes of 50-W vs 40-W during HPSD ablation of paroxysmal AF.

METHODS

Patients from the REAL-AF prospective multicenter registry (Real-World Experience of Catheter Ablation for Treatment of Symptomatic Paroxysmal and Persistent Atrial Fibrillation) undergoing HPSD ablation of paroxysmal AF, either using 50-W or 40-W, were included. The primary efficacy outcome was freedom from all-atrial arrhythmias. The primary safety outcome was the occurrence of any procedural complication at 12 months. Secondary outcomes included procedural characteristics, AF-related symptoms, and the occurrence of transient ischemic attack or stroke at 12 months.

RESULTS

A total of 383 patients were included. Freedom from all-atrial arrhythmias at 12 months was 80.7% in the 50-W group and 77.3% in the 40-W group (Log-rank P = 0.387). The primary safety outcome occurred in 3.7% of patients in the 50-W group vs 2.8% in the 40-W group (P = 0.646). The 50-W group had a higher rate of first-pass PVI (82.3% vs 76.2%; P = 0.040) as well as shorter procedural (67 minutes [IQR: 54-87.5 minutes] vs 93 minutes [IQR: 80.5-111 minutes]; P < 0.001) and radiofrequency ablation times (15 minutes [IQR: 11.4-20 minutes] vs 27 minutes [IQR: 21.5-34.6 minutes]; P < 0.001) than the 40-W group.

CONCLUSIONS

There was no significant difference in freedom from all-atrial arrhythmias or procedural safety outcomes between 50-W and 40-W during HPSD ablation of paroxysmal AF. The use of 50-W was associated with a higher rate of first-pass PVI as well as shorter procedural times.

Ablation of atrial fibrillation in an ambulatory outpatient setting

Background

The safety of atrial fibrillation (AF) ablation in an ambulatory outpatient center has not previously been reported.

Objective

The aim of this study is to report the feasibility and safety of AF ablation in an ambulatory setting.

Methods

We identified all AF ablations performed at the Alaska Heart and Vascular Institute's ambulatory center since program initiation to current day using billing records. Procedural complications, postoperative utilization of hospital services, and emergency room (ER) utilization were captured by chart review.

Results

A total of 476 patients underwent pulmonary vein isolation in the ambulatory setting over a 6.3-year period. Patients' average age was 58 ± 9.3 years, body mass index was 32.9 kg/m2, and the CHA2DS2-VASc (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, prior stroke or transient ischemic attack or thromboembolism, vascular disease, age 65-74 years, sex category) score was 1.7. For 85%, this was the first AF ablation, and 55% had paroxysmal AF. Cryoablation was used in 85%. A combined primary safety outcome capturing potentially unstable perioperative safety events occurred in 1.5% of patients, all of whom were stabilized prior to hospital transfer. A total of 1.5% of patients required same-day hospital services, with another 1.5% returning to the ER within 24 hours. A total of 96% of patients did not require hospital services within 24 hours of ablation. The 30-day ER utilization was 13.7%, similar to published data of same-day discharge of AF ablation done in the hospital setting. There were no emergent cardiac surgical interventions and no mortality events.

Conclusion

Catheter ablation for AF in the ambulatory setting is both feasible and safe in this large single-center experience. More studies are needed to confirm this next frontier in catheter ablation for AF.

Performance of the REAL-AF Same-Day Discharge Protocol in Patients Undergoing Catheter Ablation of Atrial Fibrillation

BACKGROUND

Same-day discharge (SDD) after catheter ablation of atrial fibrillation (AF) has been widely adopted. Nevertheless, planned SDD has been performed by using subjective criteria rather than standardized protocols.

OBJECTIVES

The goal of this study was to determine the efficacy and safety of the previously described SDD protocol in a prospective multicenter study.

METHODS

Using the REAL-AF (Real-world Experience of Catheter Ablation for the Treatment of Paroxysmal and Persistent Atrial Fibrillation) SDD protocol eligibility criteria (stable anticoagulation, no bleeding history, left ventricular ejection fraction >40%, no pulmonary disease, no procedures within 60 days, and body mass index <35 kg/m2), operators prospectively determined whether patients undergoing ablation of AF were candidates for SDD (SDD vs non-SDD groups). Successful SDD was achieved if the patient met the protocol discharge criteria. The primary efficacy endpoint was the success rate of SDD. The primary safety endpoints were readmission rates as well as acute and subacute complications. The secondary endpoints included procedural characteristics and freedom from all-atrial arrhythmias.

RESULTS

A total of 2,332 patients were included. The REAL-AF SDD protocol identified 1,982 (85%) patients as potential candidates for SDD. The primary efficacy endpoint was achieved in 1,707 (86.1%) patients. The readmission rate for SDD vs non-SDD group was similar (0.8% vs 0.9%; P = 0.924). The SDD group had a lower acute complication rate than the non-SDD group (0.8% vs 2.9%; P < 0.001), and there was no difference in the subacute complication rate between groups (P = 0.513). Freedom from all-atrial arrhythmias was comparable between groups (P = 0.212).

CONCLUSIONS

In this large, multicenter prospective registry, the use of a standardized protocol showed the safety of SDD after catheter ablation of paroxysmal and persistent AF. (Real-world Experience of Catheter Ablation for the Treatment of Paroxysmal and Persistent Atrial Fibrillation [REAL-AF]; NCT04088071).

Procedure-Related Complications of Catheter Ablation for Atrial Fibrillation

BACKGROUND

Catheter ablation of atrial fibrillation (AF) is a commonly performed procedure. However, it is associated with potentially significant complications. Reported procedure-related complication rates are highly variable, depending in part on study design.

OBJECTIVES

The purpose of this systematic review and pooled analysis was to determine the rate of procedure-related complications associated with catheter ablation of AF using data from randomized control trials and to assess temporal trends.

METHODS

MEDLINE and EMBASE databases were searched from January 2013 to September 2022 for randomized control trials that included patients undergoing a first ablation procedure of AF using either radiofrequency or cryoballoon (PROSPERO, CRD42022370273).

RESULTS

A total of 1,468 references were retrieved, of which 89 studies met inclusion criteria. A total of 15,701 patients were included in the current analysis. Overall and severe procedure-related complication rates were 4.51% (95% CI: 3.76%-5.32%) and 2.44% (95% CI: 1.98%-2.93%), respectively. Vascular complications were the most frequent type of complication (1.31%). The next most common complications were pericardial effusion/tamponade (0.78%) and stroke/transient ischemic attack (0.17%). The procedure-related complication rate during the most recent 5-year period of publication was significantly lower than during the earlier 5-year period (3.77% vs 5.31%; P = 0.043). The pooled mortality rate was stable over the 2 time periods (0.06% vs 0.05%; P = 0.892). There was no significant difference in complication rate according to pattern of AF, ablation modality, or ablation strategies beyond pulmonary vein isolation.

CONCLUSIONS

Procedure-related complications and mortality rates associated with catheter ablation of AF are low and have declined in the past decade.

Feasibility and Accuracy of Noninvasive Continuous Arterial Pressure Monitoring during Transcatheter Atrial Fibrillation Ablation

Introduction: Transcatheter atrial fibrillation (AF) ablation is still carried out with continuous invasive radial arterial blood pressure (IBP) monitoring in many centers. Continuous noninvasive blood pressure (CNBP) measurement using the volume-clamp method is a noninvasive alternative method used in ICU. No data on CNBP reliability are available in the electrophysiology lab during AF ablation, where rhythm variations are common. Background: The objective of the present study was to compare continuous noninvasive arterial pressure measured with the ClearSight device (Edwards Lifesciences, Irvine, CA, USA) with invasive radial artery pressure used as the reference method during AF ablation. Methods: We prospectively enrolled 55 consecutive patients (age 62 ± 11 years, 80% male) undergoing transcatheter AF ablation (62% paroxysmal, 38% persistent) at our center. Standard of care IBP monitoring via a radial cannula and a contralateral noninvasive finger volume-clamp CNBP measurement device were positioned simultaneously in all patients for the entire procedure. Bland-Altman analysis was used to analyze the agreement between the two techniques. Results: A total of 1219 paired measurements for systolic, diastolic, and mean arterial pressure were obtained in 55 subjects, with a mean (SD) of 22 (9) measurements per patient. The mean bias (SD) was −12.97 (13.89) mmHg for systolic pressure (level of agreement −14.24–40.20; correlation coefficient 0.84), −1.85 (8.52) mmHg for diastolic pressure (level of agreement −18.54–14.84; correlation coefficient 0.77) and 2.31 (8.75) mmHg for mean pressure (level of agreement −14.84–19.46; correlation coefficient 0.85). Conclusion: In patients undergoing AF ablation, CNBP monitoring with the ClearSight device showed acceptable agreement with IBP monitoring. Larger studies are needed to confirm the potential clinical implications of continuous noninvasive BP monitoring during AF ablation.

Anesthetic Management and Considerations for Electrophysiology Procedures

The number of electrophysiology (EP) procedures being performed has dramatically increased in recent years. This escalation necessitates a full understanding by the general anesthesiologist as to the risks, specific considerations, and comorbidities that accompany these now common procedures. Procedures reviewed in this article include atrial fibrillation and flutter ablation, supraventricular tachycardia ablation, ventricular tachycardia ablation, electrical cardioversion, pacemaker insertion, implantable cardioverter-defibrillator (ICD) insertion, and ICD lead extraction. General anesthetic considerations as well as procedure-specific concerns are discussed. Knowledge of these procedures will add to the anesthesiologist's armamentarium in safely caring for patients in the EP laboratory.

Cerebral safety after pulsed field ablation for paroxysmal atrial fibrillation

BACKGROUND

Pulsed field ablation (PFA) is a novel, nonthermal ablation modality that can ablate myocardial tissue with minimal effects on surrounding tissue. Preclinical data show an absence of cerebral emboli after extensive PFA. However, clinical data on silent cerebral lesions (SCLs) and/or silent cerebral events (SCEs) after PFA are lacking.

OBJECTIVES

The purpose of this study was to investigate the occurrence of neurological deficits and SCL and/or SCE after PFA in paroxysmal atrial fibrillation (AF) using National Institutes of Health Stroke Scale (NIHSS) scores and magnetic resonance imaging (MRI).

METHODS

In patients with symptomatic paroxysmal AF, pulmonary vein isolation (PVI) using PFA was performed. NIHSS scores were assessed before and 2 days and 30 days after PVI. One day after PVI, patients underwent cerebral 1.5-T MRI scanning using diffusion-weighted imaging and fluid-attenuated inversion recovery sequences to document the occurrence of SCL/SCE.

RESULTS

PFA was performed in 30 patients (age 63 ± 10 years). No patient showed neurological deficits. All NIHSS scores showed the minimum value of 0. Cerebral MRI scans were normal in 29 of 30 patients (97%). In 1 patient (3%), a single 7-mm cerebellar lesion was observed. Forty days after the procedure, follow-up cerebral MRI scan showed complete regression of the lesion.

CONCLUSION

In patients treated with PFA for symptomatic paroxysmal AF, the incidence of MRI-detected asymptomatic thromboembolic cerebral events or lesions was as low as 3%. No neurological deficits occurred in any of the patients.

Ten-year trends in mortality and complications following catheter ablation of atrial fibrillation

AIMS

Recent US studies report rising rates of mortality and in-hospital complications following catheter ablation of atrial fibrillation (AF), but whether this is a global phenomenon is uncertain. The aim of this study was to examine trends in 30-day mortality and complications following AF ablation in Australia and New Zealand (ANZ) from 2008 to 2017.

METHODS AND RESULTS

We identified 37 243 AF (mean age 62.4 ± 11.5 years, 29.6% females, 94.5% elective procedures) ablations using national hospitalization data. The primary outcome was occurrence of any complication, including all-cause mortality, within 30 days of discharge. Trends were evaluated using logistic regression adjusting for changes in patient characteristics. The annual number of ablations increased from 1359 (2008) to 5115 (2017). Patients' age and rates of heart failure (9.8-10.6%), diabetes (6.8-12.4%), and chronic kidney disease (2.2-4.1%) also increased over time. From 2008 to 2017, the overall rate of complications declined from 7.51% to 5.04% [adjusted odds ratio (aOR) 0.96 (95% confidence interval, CI, 0.94-0.97)/year]. Rates of pericardial effusion [1.69-0.70%, aOR 0.93 (0.89-0.97)], bleeding [4.49-2.74%, aOR 0.94 (0.92-0.96)], and vascular injury [0.52-0.16%, aOR 0.91 (0.85-0.98)] declined, but rates of acute kidney injury [0.15-0.68%, aOR 1.16 (1.08-1.25)] and infection [0.15-0.57%, aOR 1.07 (1.01-1.14)] increased over time. The overall 30-day mortality rate was low (0.11%) and unchanged [0.00-0.16%, aOR 0.99 (0.88-1.11)].

CONCLUSION

Despite a five-fold increase in AF ablations and the rising risk profile of patients, complications following AF ablation declined by 30% from 2008 to 2017 in ANZ. Procedure-related death was uncommon and occurred in less than 1 in 850 patients.

In-vivo porcine characterization of atrial lesion safety and efficacy utilizing a circular pulsed-field ablation catheter including assessment of collateral damage to adjacent tissue in supratherapeutic ablation applications

INTRODUCTION

Pulsed field ablation (PFA), an ablative method that causes cell death by irreversible electroporation, has potential safety advantages over radiofrequency ablation and cryoablation. Pulmonary vein (PV) isolation was performed in a porcine model to characterize safety and performance of a novel, fully-integrated biphasic PFA system comprising a multi-channel generator, variable loop circular catheter, and integrated PFA mapping software module.

METHODS

Eight healthy porcine subjects were included. To evaluate safety, multiple ablations were performed, including sites not generally targeted for therapeutic ablation, such as the right inferior PV lumen, right superior PV ostium, and adjacent to the esophagus and phrenic nerve. To evaluate efficacy, animals were recovered, followed for 30(±3) days, then re-mapped. Gross pathological and histopathological examinations assessed procedural injuries, chronic thrombosis, tissue ablation, penetration depth, healing, and inflammatory response.

RESULTS

All 8 animals survived follow-up. PV narrowing was not observed acutely nor at follow-up, even when ablation was performed deep to the PV ostium. No injury was seen grossly or histologically in adjacent structures. All PVs were durably isolated, confirmed by bidirectional block at re-map procedure. Histological examination showed complete, transmural necrosis around the circumference of the ablated section of right PVs.

CONCLUSION

This pre-clinical evaluation of a fully-integrated PFA system demonstrated effective and durable ablation of cardiac tissue and PV isolation without collateral damage to adjacent structures, even when ablation was performed in more extreme settings than those used therapeutically. Histological staining confirmed complete transmural cell necrosis around the circumference of the PV ostium at 30 days. This article is protected by copyright. All rights reserved.

The impact of hospital case volume on the outcomes after catheter ablation for atrial fibrillation according to the ablation technology

INTRODUCTION

The appropriate hospital case volume for catheter ablation (CA) in patients with atrial fibrillation (AF) according to the ablation technology has not been fully examined. This study aimed to investigate the association between the hospital case volume for AF and periprocedural complications and AF recurrence.

METHODS

In this retrospective cohort study, we used data from the National Database of Health Insurance Claims and Specific Health Checkups, which covers almost all healthcare insurance claims data in Japan. We included patients with AF who underwent first-time CA from April 2014 to March 2020. Using mixed-effect logistic regression, we analyzed the effect of the annual case volume for AF ablation on acute periprocedural complications and 1-year success rate off antiarrhythmic drugs according to the ablation technology (radiofrequency ablation or cryoballoon ablation).

RESULTS

Among 270 116 patients, 207 839 (77%) patients underwent radiofrequency ablation and 56 648 (21%) patients underwent cryoballoon ablation. Of all patients, acute complications occurred in 5411 (2.0%) patients, and the recurrence at 1 year was 71 511 (27%). In the radiofrequency ablation group, acute complications and 1-year AF recurrence according to case volume decreased as the annual case volume increased to up to 150-200 cases/year. However, in the cryoballoon ablation group, these outcomes were similar regardless of the case volumes.

CONCLUSION

The case-volume effect was noted in the radiofrequency ablation group, but not in the cryoballoon ablation group. Our results may affect the selection of ablation technology, especially in smaller case-volume hospitals.

Safety and feasibility of same-day discharge following catheter ablation of atrial fibrillation: what is known and what needs to be explored?

Catheter ablation of atrial fibrillation (AF) is the most effective rhythm control strategy and its role in the treatment of AF patients has been strengthened by recent guidelines. An increasing AF prevalence and the resulting demands on interventional electrophysiology call for improved resource allocation through both technical innovations and streamlined workflows and patient pathways. Same-day discharge is already established in the context of other electrophysiological interventions; however, its broad implementation in the practice of AF ablation is pending for several reasons, despite the fact that the body of evidence is growing and the majority of reports propagate early discharge to be feasible and safe under certain conditions. This review article is intended to provide an overview of the existing data, classify these into the specific study context, and to show limitations and open questions.

Pulsed Field Ablation: a New Paradigm for Catheter Ablation of Arrhythmias

PURPOSE OF REVIEW

Current ablation approach for arrhythmias relies upon the use of radiofrequency (RF) and cryoablation catheters. Although there have been significant advances both in catheter design and in energy delivery approaches, limitations such as suboptimal efficacy and safety remain. Pulsed field ablation (PFA) has emerged as a novel approach to ablation that is distinct from RF and cryoablation by virtue of selective ablation of myocardial tissue. Preclinical and clinical reports have demonstrated lesion durability with an excellent safety profile. These findings need to be confirmed in prospective randomized trials that are currently ongoing. In this review, we describe efficacy and safety outcomes from both pre-clinical and clinical studies that have been performed so far and briefly discuss ongoing clinical trials and future investigations.

RECENT FINDINGS

Data from pre-clinical and clinical research have shown PFA as a promising tool for ablation of cardiac arrhythmias. In addition to safety regarding mitigating the risk to surrounding structures such as the phrenic nerve, esophagus, PFA also offers an effective method for ablation. In this review, we summarize the currently published pre-clinical and clinical data evaluating the safety and efficacy of PFA for cardiac arrhythmias.

A Comparative Modeling Study of Thermal Mitigation Strategies in Irreversible Electroporation Treatments

Irreversible electroporation (IRE), also referred to as nonthermal pulsed field ablation (PFA), is an attractive focal ablation modality for solid tumors and cardiac tissue due to its ability to destroy aberrant cells with limited disruption of the underlying tissue architecture. Despite its nonthermal cell death mechanism, application of electrical energy results in Joule heating that, if ignored, can cause undesired thermal injury. Engineered thermal mitigation (TM) technologies including phase change materials (PCMs) and active cooling (AC) have been reported and tested as a potential means to limit thermal damage. However, several variables affect TM performance including the pulsing paradigm, electrode geometry, PCM composition, and chosen active cooling parameters, meaning direct comparisons between approaches are lacking. In this study, we developed a computational model of conventional bipolar and monopolar probes with solid, PCM-filled, or actively cooled cores to simulate clinical IRE treatments in pancreatic tissue. This approach reveals that probes with integrated PCM cores can be tuned to drastically limit thermal damage compared to existing solid probes. Furthermore, actively cooled probes provide additional control over thermal effects within the probe vicinity and can altogether abrogate thermal damage. In practice, such differences in performance must be weighed against the increased time, expense, and effort required for modified probes compared to existing solid probes.

Catheter ablation for atrial fibrillation can be safely performed without invasive hemodynamic monitoring: A multi-center study

BACKGROUND

Arterial invasive monitoring is the most common method in the USA for hemodynamic monitoring during atrial fibrillation (AF) ablation. Although studies have shown favorable comparison between non-invasive and invasive hemodynamic monitoring (IHM) in non-cardiac procedures under general anesthesia, limited data is available for complex cardiac procedures such as AF ablation in the USA. With progressive improvement in AF ablation procedural safety, particularly with routine use of intracardiac echocardiography (ICE) to monitor for pericardial effusion, it is unclear if invasive hemodynamic monitoring provides any advantage over non-invasive methods. Therefore, the purpose of this study is to determine whether noninvasive hemodynamic monitoring is non-inferior to invasive hemodynamic monitoring during AF ablation under general anesthesia in patients without major cardiac structural abnormality.

METHODS

A multi-center retrospective data of AF ablation from July 2019 to December 2020 was extracted. A total of three hundred and sixty-two patients (362) were included, which were divided into group A (non-invasive hemodynamic monitoring) and group B (invasive hemodynamic monitoring). The primary outcome was to compare procedural safety between the two groups.

RESULTS

Out of 362 patients, 184 (51%) received non-invasive and 178 (49%) received invasive hemodynamic monitoring with similar baseline characteristics. There was no significant difference between the two groups in complication rates (groin hematoma, pericardial effusion, cardiac tamponade). Mean procedure time was longer in group B with 3.35% arterial site discomfort. Urgent arterial access was required in only 1 patient in group A.

CONCLUSION

This retrospective multicenter study strongly suggests that catheter ablation for atrial fibrillation under general anesthesia can be safely performed with noninvasive hemodynamic monitoring without requiring arterial access, with potential benefit in procedural duration and cost.

Proper use of fentanyl facilitates anesthesia during pulmonary vein isolation

Although intraoperative anesthetic management of extensive encircling pulmonary vein isolation (PVI) is essential for the safe performance of this procedure, there is no standardized approach for the use of sedation and analgesia. Therefore, the present study aimed to clarify the optimal fentanyl dosage and timing of administration for the anesthetic management during PVI. A total of 364 patients with atrial fibrillation (AF) who underwent PVI at our institution between June 2017 and October 2020 were recruited. All patients were anesthetized with propofol for induction and maintenance under controlled ventilation via the supraglottic airway without neuromuscular blocking drugs. Among them, 234 patients received less frequent injections (Group 1) and 130 received a scheduled injection of 50 mg of fentanyl (Group 2) in addition to propofol during PVI. We compared the total and additional propofol doses, frequency of additional propofol, and procedure time between the two groups. The mean patient age was 67.2 years, and 69% were male. The total propofol dose was significantly lower in Group 2 than in Group 1 (17.0 ± 5.2 mg/kg vs. 19.0 ± 5.5 mg/kg, p < 0.01). The loading dose and frequency of additional propofol were also significantly lower in Group 2 than in Group 1. The procedure time was significantly shorter in Group 2 than in Group 1 (119 ± 36 min vs. 132 ± 31 min, p < 0.01). During PVI, proper use of fentanyl decreased the propofol dose, additional propofol frequency, and procedure time.

First-in-Human Experience and Acute Procedural Outcomes Using a Novel Pulsed Field Ablation System: The PULSED AF Pilot Trial

Supplemental Digital Content is available in the text.

Background:

Pulsed field ablation (PFA) is a novel form of ablation using electrical fields to ablate cardiac tissue. There are only limited data assessing the feasibility and safety of this type of ablation in humans.

Methods:

PULSED AF (Pulsed Field Ablation to Irreversibly Electroporate Tissue and Treat AF; https://www.clinicaltrials.gov; unique identifier: NCT04198701) is a nonrandomized, prospective, multicenter, global, premarket clinical study. The first-in-human pilot phase evaluated the feasibility and efficacy of pulmonary vein isolation using a novel PFA system delivering bipolar, biphasic electrical fields through a circular multielectrode array catheter (PulseSelect; Medtronic, Inc). Thirty-eight patients with paroxysmal or persistent atrial fibrillation were treated in 6 centers in Australia, Canada, the United States, and the Netherlands. The primary outcomes were ability to achieve acute pulmonary vein isolation intraprocedurally and safety at 30 days.

Results:

Acute electrical isolation was achieved in 100% of pulmonary veins (n=152) in the 38 patients. Skin-to-skin procedure time was 160±91 minutes, left atrial dwell time was 82±35 minutes, and fluoroscopy time was 28±9 minutes. No serious adverse events related to the PFA system occurred in the 30-day follow-up including phrenic nerve injury, esophageal injury, stroke, or death.

Conclusions:

In this first-in-human clinical study, 100% pulmonary vein isolation was achieved using only PFA with no PFA system–related serious adverse events.

Graphic Abstract:

A graphic abstract is available for this article.

Cryoballoon ablation vs. antiarrhythmic drugs: first-line therapy for patients with paroxysmal atrial fibrillation

AIMS

Treatment guidelines for patients with atrial fibrillation (AF) suggest that patients should be managed with an antiarrhythmic drug (AAD) before undergoing catheter ablation (CA). This study evaluated whether pulmonary vein isolation employing cryoballoon CA is superior to AAD therapy for the prevention of atrial arrhythmia (AA) recurrence in rhythm control naive patients with paroxysmal AF (PAF).

METHODS AND RESULTS

A total of 218 treatment naive patients with symptomatic PAF were randomized (1 : 1) to cryoballoon CA (Arctic Front Advance, Medtronic) or AAD (Class I or III) and followed for 12 months. The primary endpoint was ≥1 episode of recurrent AA (AF, atrial flutter, or atrial tachycardia) >30 s after a prespecified 90-day blanking period. Secondary endpoints included the rate of serious adverse events (SAEs) and recurrence of symptomatic palpitations (evaluated via patient diaries). Freedom from AA was achieved in 82.2% of subjects in the cryoballoon arm and 67.6% of subjects in the AAD arm (HR = 0.48, P = 0.01). There were no group differences in the time-to-first (HR = 0.76, P = 0.28) or overall incidence [incidence rate ratio (IRR)=0.79, P = 0.28] of SAEs. The incidence rate of symptomatic palpitations was lower in the cryoballoon (7.61 days/year) compared with the AAD arm (18.96 days/year; IRR = 0.40, P < 0.001).

CONCLUSIONS

Cryoballoon CA was superior to AAD therapy, significantly reducing AA recurrence in treatment naive patients with PAF. Additionally, cryoballoon CA was associated with lower symptom recurrence and a similar rate of SAEs compared with AAD therapy.

Utilization and perception of same-day discharge in electrophysiological procedures and device implantations: an EHRA survey

The aim of this European Heart Rhythm Association (EHRA) survey was to assess the utilization of same-day discharge (SDD) in electrophysiology (EP). An online-based questionnaire was shared with the EHRA community between 12 and 30 June 2020 and recorded institutional information, complication assessment, recent experiences, and opinions regarding possible advantages or concerns with SDD. In total, 218 responses from 49 countries provided information on current SDD management. Overall, SDD was implemented in 77.5%, whereas this proportion was significantly higher in tertiary and high-volume centres (83.8% and 85.3%, both P < 0.01). The concept of SDD was most commonly used following implantations of cardiac event recorders (97%), diagnostic EP procedures (72.2%), and implantations of pacemakers with one or two intracardiac leads (50%), while the lowest SDD utilization was observed after catheter ablations of left atrial or ventricular arrhythmias. Within SDD-experienced centres, ∼90% respondents stated that this discharge concept is recommendable or highly recommendable and reported that rates of increased rehospitalization and complication rates were low. Most respondents assumed a better utilization of hospital resources (78.2%), better cost effectiveness (77.3%), and an improved patients' comfort but were concerned about possible impairment of detection (72.5%) and management (78.7%) of late complications. In conclusion, >75% of respondents already implement SDD following EP interventions with a large heterogeneity with regard to specific procedures. Further research is needed to confirm or disprove existing and expected benefits and obstacles.

In vivo analysis of the origin and characteristics of gaseous microemboli during catheter-mediated irreversible electroporation

Aims 

Irreversible electroporation (IRE) ablation is a non-thermal ablation method based on the application of direct current between a multi-electrode catheter and skin electrode. The delivery of current through blood leads to electrolysis. Some studies suggest that gaseous (micro)emboli might be associated with myocardial damage and/or (a)symptomatic cerebral ischaemic events. The aim of this study was to compare the amount of gas generated during IRE ablation and during radiofrequency (RF) ablation.

Methods and results

In six 60–75 kg pigs, an extracorporeal femoral shunt was outfitted with a bubble-counter to detect the size and total volume of gas bubbles. Anodal and cathodal 200 J IRE applications were delivered in the left atrium (LA) using a 14-electrode circular catheter. The 30 and 60 s 40 W RF point-by-point ablations were performed. Using transoesophageal echocardiography (TOE), gas formation was visualized. Average gas volumes were 0.6 ± 0.6 and 56.9 ± 19.1 μL (P < 0.01) for each anodal and cathodal IRE application, respectively. Also, qualitative TOE imaging showed significantly less LA bubble contrast with anodal than with cathodal applications. Radiofrequency ablations produced 1.7 ± 2.9 and 6.7 ± 7.4 μL of gas, for 30 and 60 s ablation time, respectively.

Conclusion 

Anodal IRE applications result in significantly less gas formation than both cathodal IRE applications and RF applications. This finding is supported by TOE observations.

The Care of Patients With Atrial Fibrillation and Heart Failure

Atrial fibrillation (AF) and heart failure (HF) are the 2 emerging epidemics in global cardiovascular disease. AF remains the most common cardiac arrhythmia, affecting over 33 million adults worldwide, and continues to increase in prevalence as the populations of many nations age. The prevalence of HF also surges, now afflicting 37 million adults globally. Interestingly, these 2 disease processes share many of the same risk factors and stem from many of the same pathophysiologic derangements, with AF occurring in over half of all patients with HF and HF occurring in over one third of all patients with AF. Furthermore, exacerbation of one of these ailments often drives decompensation or compromises therapy of the other, and it has been widely reported that coexistence of AF in patients with HF portends a poorer prognosis. As a result, many clinicians now routinely face the problem of AF in the patient with HF. In this review, we highlight the fundamental pathologic forces embedded in the relationship between AF and HF and then proceed to a discussion on the management of these complex patients with a detailed exploration of the clinical data.

Catheter Ablation vs. Anti-Arrhythmic Drugs as First-Line Treatment in Symptomatic Paroxysmal Atrial Fibrillation: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Background: Catheter ablation has become a well-established indication for long-term rhythm control in atrial fibrillation (AF) patients refractory to anti-arrhythmic drugs (AADs). Efficacy and safety of AF catheter ablation (AFCA) before AADs failure are, instead, questioned. Objective: The aim of the study was to perform a systematic review and meta-analysis of randomized clinical trials (RCTs) comparing first-line AFCA with AADs in symptomatic patients with paroxysmal AF. Methods: We performed a random-effects meta-analysis of binary outcome events comparing AFCA with AADs in rhythm control-naïve patients. The primary outcomes, also stratified by the type of ablation energy (radiofrequency or cryoenergy), were (1) recurrence of atrial tachyarrhythmias and (2) recurrence of symptomatic atrial tachyarrhythmias. The secondary outcomes included adverse events. Results: Six RCTs were included in the analysis. AFCA was associated with lower recurrences of atrial tachyarrhythmias [relative risk (RR) 0.58, 95% confidence interval (CI) 0.46-0.72], consistent across the two types of ablation energy (radiofrequency, RR 0.50, 95% CI 0.28-0.89; cryoenergy, RR 0.60, 95% CI 0.50-0.72; p-value for subgroup differences: 0.55). Similarly, AFCA was related to less symptomatic arrhythmic recurrences (RR 0.46, 95% CI 0.27-0.79). Overall, adverse events did not differ. A trend toward increased periprocedural cardiac tamponade or phrenic nerve palsy was observed in the AFCA group, while more atrial flutter episodes with 1:1 atrioventricular conduction and syncopal events were reported in the AAD group. Conclusions: First-line rhythm control therapy with AFCA, independent from the adopted energy source (radiofrequency or cryoenergy), reduces long-term arrhythmic recurrences in patients with symptomatic paroxysmal AF compared with AADs.

Reduction of mortality by catheter ablation in real-world atrial fibrillation patients with heart failure

Whether catheter ablation for atrial fibrillation (AF) improves survival and affects other outcomes in real-world heart failure (HF) patients is unclear. This study aimed to evaluate whether ablation reduces death, and other outcomes in real-world AF patients with HF. Among 834,735 patients with AF from 2006 to 2015 in the Korean National Health Insurance Service database, 3173 HF patients underwent AF ablation. Propensity score weighting was used to correct for differences between the groups. During median 54 months follow-up, the risk of all-cause death in ablated patients was less than half of that in patients with medical therapy (2.8 vs. 6.2 per 100 person-years; hazard ratio [HR] 0.42, 95% confidence interval [CI] 0.27–0.65, p < 0.001). Ablation was related with lower risk of cardiovascular death (HR 0.38, 95% CI 0.32–0.62, p < 0.001), HF admission (HR 0.39, 95% CI 0.33–0.46, p < 0.001) and stroke/systemic embolism (HR 0.44, 95% CI 0.37–0.53, p < 0.001). In subgroup analysis, the risk of all-cause death was reduced in most subgroups except in the elderly (≥ 75 years) and strictly anticoagulated patients. Ablation may be associated with reduced risk of all-cause death and cardiovascular death in real-world AF patients with HF, supporting the role of AF ablation in patients with HF.

Prospective implementation of a same-day discharge protocol for catheter ablation of paroxysmal atrial fibrillation

PURPOSE

Overnight stays associated with catheter ablation (CA) for paroxysmal atrial fibrillation (PAF) account for a significant proportion of treatment cost. Same-day discharge (SDD) after CA may be attractive to both patients and hospitals, especially in light of current restrictions on overnight stays due to COVID-19. This study reports on the selection criteria, protocol, and safety of SDD after CA of PAF.

METHODS

Patients undergoing CA for PAF were evaluated to assess the risk of groin, respiratory, cardiac, or bleeding complications. SDD eligibility criteria were stable anticoagulation with no bleeding history, systolic heart failure, respiratory conditions, or interventional procedures within 60 days, and recommended BMI < 35. Patient proximity to the hospital was also considered. Anesthesia with propofol was used, and ablations were performed with a contact force catheter. Patients rested for 6 h post-procedure and then ambulated over 1-2 h. Discharge followed if they were stable without evidence of complications. A nurse called all patients the following morning to elicit evidence of complications.

RESULTS

Of 44 planned SDD procedures between April 2017 and June 2018, 41 resulted in SDD after 7.2 ± 1.0 h, 2 patients stayed overnight for observation, and one by choice. Average age was 59 ± 10 years with CHA₂DS₂-VASc of 1.6 ± 1.1. No SDD-related complications occurred, and no return visits resulted from the follow-up calls.

CONCLUSION

Appropriate low-risk patients identified by well-defined clinical criteria can be safely discharged the same day after CA for PAF. Evaluation in a larger population across different centers is required for generalizability of this SDD protocol.

Safety and Efficacy of Minimal- versus Zero-fluoroscopy Radiofrequency Catheter Ablation for Atrial Fibrillation: A Multicenter, Prospective Study

Radiofrequency catheter ablation (CA) is an effective treatment for atrial fibrillation (AF) that traditionally requires fluoroscopic imaging to guide catheter movement and positioning. However, advances in electroanatomic mapping (EAM) technology and intracardiac echocardiography (ICE) have reduced procedural reliance on fluoroscopy. We conducted a prospective registry study of 162 patients enrolled at five centers proficient in high-volume, minimal-fluoroscopy CA between March 2016 and March 2018 for the CA of symptomatic, drug-refractory paroxysmal, or persistent AF that sought to assess the safety and efficacy of minimal- versus zero-fluoroscopy AF CA. We evaluated procedural details, acute procedural outcomes and complications, and one-year follow-up data. All operators used an EAM system (CARTO^®; Biosense Webster, Irvine, CA, USA) and ICE. Ultimately, two patients did not pursue CA postenrollment. A total of 104 (66%) patients had paroxysmal AF with a mean ejection fraction of 58% ± 9%. Twenty-six (16.3%) patients were scheduled for repeat ablation. A total of 100 (63%) procedures were performed with zero fluoroscopy. The mean fluoroscopy time in the minimal-fluoroscopy group was 1.7 minutes ± 2.8 minutes. Further, the mean procedure duration was 192 minutes ± 37 minutes in the zero-fluoroscopy group and 201 minutes ± 29 minutes in the minimal-fluoroscopy group (p = 0.96). Pulmonary vein isolation was achieved in 153 patients (100%), with an acute procedural complication rate of 1.8%. One-year follow-up data were available for 152 (95%) patients with a mean follow-up time of 11.3 months ± 1.8 months. A total of 118 (76%) patients remained free from arrhythmia for up to 12 months, with no difference between the minimal- and zero-fluoroscopy cohorts (p = 0.18).

A decade of catheter ablation of cardiac arrhythmias in Sweden: ablation practices and outcomes

Aims

Catheter ablation is considered the treatment of choice for many tachyarrhythmias, but convincing ‘real-world’ data on efficacy and safety are lacking. Using Swedish national registry data, the ablation spectrum, procedural characteristics, as well as ablation efficacy and reported adverse events are reported.

Methods and Results

Consecutive patients (≥18 years of age) undergoing catheter ablation in Sweden between 01 January 2006 and 31 December 2015 were included in the study. Follow-up (repeat ablation and vital status) was collected through 31 December 2016. A total of 26 642 patients (57 ± 15 years, 62% men), undergoing a total of 34 428 ablation procedures were included in the study. In total, 4034 accessory pathway/Wolff–Parkinson–White syndrome (12%), 7358 AV-nodal re-entrant tachycardia (21%), 1813 atrial tachycardia (5.2%), 5481 typical atrial flutter (16%), 11 916 atrial fibrillation (AF, 35%), 2415 AV-nodal (7.0%), 581 premature ventricular contraction (PVC, 1.7%), and 964 ventricular tachycardia (VT) ablations (2.8%) were performed. Median follow-up time was 4.7 years (interquartile range 2.7–7.0). The spectrum of treated arrhythmias changed over time, with a gradual increase in AF, VT, and PVC ablation (P < 0.001). Decreasing procedural times and utilization of fluoroscopy with time, were seen for all arrhythmia types. The rates of repeat ablation differed between ablation types, with the highest repeat ablation seen in AF (41% within 3 years). The rate of reported adverse events was low (n = 595, 1.7%). Death in the immediate period following ablation was rare (n = 116, 0.34%).

Conclusion

Catheter ablations have shifted towards more complex procedures over the past decade. Fluoroscopy time has markedly decreased and the efficacy of catheter ablation seems to improve for AF.

Risk factors for venous bleeding complication at the femoral puncture site after catheter ablation of atrial fibrillation

BACKGROUND

Venous bleeding complication is often observed after catheter ablation of atrial fibrillation (AF), but the risk factors remain unclear.

METHODS

We retrospectively evaluated 570 consecutive patients who underwent catheter ablation of AF from April 2012 to March 2017. After the procedure, the sheaths were removed, and hemostasis was obtained by manual compression followed by application of rolled gauze with elastic bandage and continuous pressure to the puncture site. We evaluated the risk factors for venous bleeding complications defined as hemorrhage from the puncture site that needed recompression after removal of the elastic bandage and rolled gauze.

RESULTS

After excluding 11 patients because of missing data, 559 patients (395 [70.7%] men, mean age: 65.6 ± 8.7 years) were included for analysis. Venous bleeding complication was observed in 213 patients (38.1%). In the multivariate logistic regression analysis, low body mass index (BMI; odds ratio [OR] 0.95, 95% CI 0.90-1.00, P = .04), short compression time (OR 0.77, 95% CI 0.68-0.88, P < .001), and antiplatelet therapy (OR 1.86, 95% CI 1.09-3.16, P = .02) were independent risk factors for venous bleeding complication.

CONCLUSIONS

Low BMI, short compression time, and antiplatelet therapy were independent risk factors for venous bleeding complication after catheter ablation of AF. Longer compression time may be needed for patients with low BMI and/or those receiving antiplatelet therapy.

Procedural Patterns and Safety of Atrial Fibrillation Ablation: Findings From Get With The Guidelines-Atrial Fibrillation

BACKGROUND

Catheter ablation is an increasingly used treatment for symptomatic atrial fibrillation (AF). However, there are limited prospective, nationwide data on patient selection and procedural characteristics. This study describes patient characteristics, techniques, treatment patterns, and safety outcomes of patients undergoing AF ablation.

METHODS

A total of 3139 patients undergoing AF ablation between 2016 and 2018 in the Get With The Guidelines-Atrial Fibrillation registry from 24 US centers were included. Patient demographics, medical history, procedural details, and complications were abstracted. Differences between paroxysmal and patients with persistent AF were compared using Pearson χ² and Wilcoxon rank-sum tests.

RESULTS

Patients undergoing AF ablation were predominantly male (63.9%) and White (93.2%) with a median age of 65. Hypertension was the most common comorbidity (67.6%), and patients with persistent AF had more comorbidities than patients with paroxysmal AF. Drug refractory, paroxysmal AF was the most common ablation indication (class I, 53.6%) followed by drug refractory, persistent AF (class I, 41.8%). Radiofrequency ablation with contact force sensing was the most common ablation modality (70.5%); 23.7% of patients underwent cryoballoon ablation. Pulmonary vein isolation was performed in 94.6% of de novo ablations; the most common adjunctive lesions included left atrial roof or posterior/inferior lines, and cavotricuspid isthmus ablation. Complications were uncommon (5.1%) and were life-threatening in 0.7% of cases.

CONCLUSIONS

More than 98% of AF ablations among participating sites are performed for class I or class IIA indications. Contact force-guided radiofrequency ablation is the dominant technique and pulmonary vein isolation the principal lesion set. In-hospital complications are uncommon and rarely life-threatening.

Pulsed Field Ablation Using a Lattice Electrode for Focal Energy Delivery: Biophysical Characterization, Lesion Durability, and Safety Evaluation

BACKGROUND

Pulsed field ablation (PFA) is a nonthermal energy that may provide safety advantages over radiofrequency ablation (RFA). One-shot PFA catheters have been developed for pulmonary vein isolation, but they do not permit flexible lesion sets. This study investigated a novel lattice-tip catheter designed for focal RFA or PFA ablation.

METHODS

The effects of PFA (biphasic, 24 amperes) were investigated in 25 swine using a lattice-tip catheter and system (Affera Inc). Step 1 (n=14) examined the feasibility to create atrial line of block and described its acute effects on the phrenic nerve and esophagus. Step 2 (n=7) examined the subacute effects of PFA on block durability, phrenic nerve, and esophagus ≥2 weeks. Step 3 compared the effects of PFA and RFA on the esophagus using a mechanical deviation model approximating the esophagus to the right atrium (n=4) and by direct ablation within its lumen (n=4). The effects of endocardial PFA and RFA on the phrenic nerve were also compared (n=10). Histological analysis was performed.

RESULTS

PFA produced acute block in 100% of lines, achieved with 2.1 (1.3-3.2) applications/cm line. Histological analysis following (35 [18-37]) days showed 100% transmurality (thickness range 0.4-3.4 mm) with a lesion width of 19.4 (10.9-27.4 mm). PFA selectively affected cardiomyocytes but spared blood vessels and nervous tissue. PFA applied from the posterior atria (23 [21-25] applications) to the approximated esophagus (6 [4.5-14] mm) produced transmural lesions without esophageal injury. PFA (16.5 [15-18] applications) applied inside the esophageal lumen produced mild edema compared with RFA (13 [12-14] applications) which produced epithelial ulcerations. PFA resulted in no or transient stunning of the phrenic nerve (<5 minutes) without histological changes while RFA produced paralysis.

CONCLUSIONS

PFA using a lattice-tip ablation catheter for focal ablation produced durable atrial lesions and showed lower vulnerability to esophageal or phrenic nerve damage compared with RFA.

Esophageal injury associated with catheter ablation for atrial fibrillation: Determinants of risk and protective strategies

Catheter ablation has become an important element in the management of atrial fibrillation. Several technical advances allowed for better safety profiles and lower recurrence rates, leading to an increasing number of ablations worldwide. Despite that, major complications are still reported, and esophageal thermal injury remains a significant concern as atrioesophageal fistula (AEF) is often fatal. Recognition of the mechanisms involved in the process of esophageal lesion formation and the identification of the main determinants of risk have set the grounds for the development and improvement of different esophageal protective strategies. More sensitive esophageal temperature monitoring, safer ablation parameters and catheters, and different energy sources appear to collectively reduce the risk of esophageal thermal injury. Adjunctive measures such as the prophylactic use of proton-pump inhibitors, as well as esophageal cooling or deviation devices, have emerged as complementary methods with variable but promising results. Nevertheless, as a multifactorial problem, no single esophageal protective measure has proven to be sufficiently effective to eliminate the risk, and further investigation is still warranted. Early screening in the patients at risk and prompt intervention in the cases of AEF are important risk modifiers and yield better outcomes.

High-power, Short-duration Radiofrequency Ablation for the Treatment of AF

High-power, short-duration (HPSD) ablation for the treatment of AF is emerging as an alternative to ablation using conventional ablation generator settings characterised by lower power and longer duration. Although the reported potential advantages of HPSD ablation include less tissue oedema and collateral tissue damage, a reduction in procedural time and superior ablation lesion formation, clinical studies of HPSD ablation validating these observations are limited. One of the main challenges for HPSD ablation has been the inability to adequately assess temperature and lesion formation in real time. Novel catheter designs may improve the accuracy of intra-ablation temperature recording and correspondingly may improve the safety profile of HPSD ablation. Clinical studies of HPSD ablation are on-going and interpretation of the data from these and other studies will be required to ascertain the clinical value of HPSD ablation.

Thermodynamic properties of atrial fibrillation cryoablation: a model-based approach to improve knowledge on energy delivery

The objective of this study is to describe a suitable model of atrial fibrillation cryoablation thermodynamic properties. Three different thermal loads were applied to a cylindrical copper element simulating the cryoprobe, thermally coupled with a Peltier stack producing the freezing effect, and in contact with a bovine liver sample. Thermal events occurring inside the samples were measured using mirror image technique. Heat subtracted flux during ice formation and minimum temperature measured at probe-tissue interface were, respectively, 1.33 W cm^-2 and -27.8°C for Sample#0, 1.88 W cm^-2 and -35.6°C for Sample#1 and 1.82 W cm^-2 and 1.44 W cm^-2 before and after the ice trigger, respectively, and -29.3°C for Sample#2. Ice trigger temperature was around -8.5°C for Sample#0 and Sample#2, and -10.4°C for Sample#1. In all the investigated samples, ice front penetration was proportional to the square root of time and its velocity depended on the heat flux subtracted. The fraction of the useful energy spent for ice formation was less than 60% for Sample#0, and about 80% for Sample#1 and for Sample#2, before the reduction of the removed heat flux. Freezing time exceeding a cut-off, according to the heat subtracted flux, does not improve the procedure effectiveness and is detrimental to the surrounding tissues.

High-frequency irreversible electroporation for cardiac ablation using an asymmetrical waveform

Background

Irreversible electroporation (IRE) using direct current (DC) is an effective method for the ablation of cardiac tissue. A major drawback of the use of DC-IRE, however, are two problems: requirement of general anesthesia due to severe muscle contractions and the formation of bubbles containing gaseous products from electrolysis. The use of high-frequency alternating current (HF-IRE) is expected to solve both problems, because HF-IRE produces little to no muscle spasms and does not cause electrolysis.

Methods

In the present study, we introduce a novel asymmetric, high-frequency (aHF) waveform for HF-IRE and present the results of a first, small, animal study to test its efficacy.

Results

The data of the experiments suggest that the aHF waveform creates significantly deeper lesions than a symmetric HF waveform of the same energy and frequency (p = 0.003).

Conclusion

We therefore conclude that the use of the aHF enhances the feasibility of the HF-IRE method.

Association between the use of contact force-sensing catheters and cardiac tamponade in atrial fibrillation ablation

Introduction

Cardiac tamponade is a rare but life-threatening complication during atrial fibrillation (AF) catheter ablation. Contact force (CF)–sensing catheters improve ablation effectiveness. However, the impact of the application of CF-sensing catheters on the occurrence of cardiac tamponade remains unclear. The aim of this study is to evaluate the “real-world” impact of CF-sensing catheters on cardiac tamponade during AF ablation in an experienced medical center.

Methods and results

This was a retrospective study of consecutive de novo AF ablation procedures at Beijing Anzhen Hospital between 2013 and 2016. The ablation procedure was divided into a CF group and a non-CF group. Logistic regression analysis was used to evaluate the association between the use of CF-sensing catheters and the risk of cardiac tamponade. A total of 5313 patients with AF were involved in this study. The incidence of cardiac tamponade in the CF group was significantly higher than that in the non-CF group (1.07% vs. 0.44%, P = 0.009). Of the cardiac tamponade cases in the non-CF group, 45.45% were delayed compared with 10% in the CF group (P = 0.011). Multivariate logistic regression analysis showed that CF-sensing catheters increased the risk of cardiac tamponade (OR = 2.34, 95% CI = 1.17–4.26, P = 0.015). Stratified analysis revealed patients with a smaller left atrium dimension, lower ejection fraction, longer procedure duration, or longer ablation duration had a greater risk of cardiac tamponade during ablation with CF-sensing catheters.

Conclusions

CF-sensing catheters increase the risk of cardiac tamponade during AF ablation.

Electronic supplementary material

The online version of this article (10.1007/s10840-019-00516-z) contains supplementary material, which is available to authorized users.

Low-fluoroscopy atrial fibrillation ablation with contact force and ultrasound technologies: a learning curve

Background

Fluoroscopy exposure during catheter ablation is a health hazard to patients and operators. This study presents the results of implementing a low-fluoroscopy workflow using modern contact force (CF) technologies in paroxysmal atrial fibrillation (PAF) ablation.

Methods

A fluoroscopy reduction workflow was implemented and subsequent catheter ablations for PAF were evaluated. After vascular access with ultrasound guidance, a THERMOCOOL SMARTTOUCH^® Catheter (ST) was advanced into the right atrium. The decapolar catheter was placed without fluoroscopy. A double-transseptal puncture was performed under intracardiac echocardiography guidance. ST and mapping catheters were advanced into the left atrium. A left atrial map was created, and pulmonary vein (PV) isolation was confirmed via entrance and exit block before and after the administration of isoproterenol or adenosine.

Results

Forty-three patients underwent PAF ablation with fluoroscopy reduction workflow (mean age: 66±9 years; 70% male), performed by five operators. Acute success rate (PV isolation) was 96.5% of PVs. One case of pericardial effusion, not requiring intervention, was the only acute complication. Mean procedure time was 217±42 minutes. Mean fluoroscopy time was 2.3±3.0 minutes, with 97.7% of patients having < 10 minutes and 86.0% having < 5 minutes. A significant downward trend over time was observed, suggesting a rapid learning curve for fluoroscopy reduction. Freedom from any atrial arrhythmias without reablation was 80.0% after a mean follow-up of 12±3 months.

Conclusion

Low fluoroscopy time is achievable with CF technologies after a short learning curve, without compromising patient safety or effectiveness.