Randomized, Controlled Trial of the Safety and Effectiveness of a Contact Force-Sensing Irrigated Catheter for Ablation of Paroxysmal Atrial Fibrillation: Results of the TactiCath Contact Force Ablation Catheter Study for Atrial Fibrillation (TOCCASTAR) Study

Safety, effectiveness, and quality of life following pulmonary vein isolation with a multi-electrode radiofrequency balloon catheter in paroxysmal atrial fibrillation: 1-year outcomes from SHINE

AIMS

To evaluate the safety and effectiveness of a compliant multi-electrode radiofrequency balloon catheter (RFB) used with a multi-electrode diagnostic catheter for pulmonary vein isolation (PVI).

METHODS AND RESULTS

This prospective, multicentre, single-arm study was conducted at six European sites and enrolled patients with symptomatic paroxysmal atrial fibrillation. The primary effectiveness endpoint was entrance block in treated pulmonary veins (PVs) after adenosine/isoproterenol challenge. The primary safety endpoint was the occurrence of primary adverse events (PAEs) within 7 days. Cerebral magnetic resonance imaging and neurological assessments were performed pre- and post-ablation in a subset of patients. Atrial arrhythmia recurrence was assessed over 12 months via transtelephonic and Holter monitoring. Quality of life was assessed by the Atrial Fibrillation Effect on Quality of Life (AFEQT) questionnaire. Of 85 patients undergoing ablation per study protocol, PV entrance block was achieved in all (one PV required touch-up with a focal catheter). Acute reconnection of ≥1 PVs after adenosine/isoproterenol challenge was observed in 9.3% (30/324) of PVs ablated. Post-ablation, silent cerebral lesions were detected in 9.7% (3/31) of patients assessed, all of which was resolved at 1-month follow-up. One patient experienced a PAE (retroperitoneal bleed). Freedom from documented symptomatic and all arrhythmia was 72.2% and 65.8% at 12 months. Four patients (4.7%) underwent repeat ablation. Significant improvements in all AFEQT subscale scores were seen at 6 and 12 months.

CONCLUSION

PVI with the novel RFB demonstrated favourable safety and effectiveness, with low repeat ablation rate and clinically meaningful improvement in quality of life.

CLINICALTRIALS.GOV REGISTRATION NUMBER

NCT03437733.

Novel concepts in atrial fibrillation ablation-breaking the trade-off between efficacy and safety

Despite substantial technological and procedural advances that have improved the efficacy and safety of AF ablation in recent years, the long-term durability of ablation lesions is still not satisfactory. There also remains concern regarding rare but potentially life-threatening procedure-related complications like cardiac tamponade and atrioesophageal fistulae. Current ablation strategies are aiming to optimize the trade-off between efficacy and safety, where more extensive ablation appears to inevitably increase the risk of collateral injury. However, new forms of energy application may have the potential to resolve this quandary. The emerging concept of high power-short duration radiofrequency ablation features a more favorable lesion geometry that appears ideally suited to create contiguous lesions in the thin-walled atrium. Moreover, novel non-thermal ablation methods based on electroporation appear to provide a unique selectivity for cardiomyocytes and to spare surrounding tissues composed of other cell types. Both, high power-short duration and electroporation ablation might have the potential to break the trade-off between effective lesions and collateral damage and to substantially improve risk-benefit ratios in AF ablation. In addition, both approaches lead to considerable reductions in ablation times. However, their putative benefits regarding efficacy, efficiency, and safety remain to be proven in randomized controlled trials.

Efficacy and safety of the GOLD FORCE multicentre randomized clinical trial: multielectrode phased radiofrequency vs. irrigated radiofrequency single-tip catheter with contact force ablation for treatment of symptomatic paroxysmal atrial fibrillation

AIMS

Pulmonary vein isolation (PVI) for atrial fibrillation (AF) has become increasingly safe and effective with the evolution of single-tip ablation catheters aided by contact force sensing (ST-CF) and single-shot devices such as the second-generation pulmonary vein ablation catheter (PVAC) Gold multi-electrode array. The multicentre randomized GOLD FORCE trial was conducted to evaluate non-inferiority of safety and efficacy of PVAC Gold PVI compared to ST-CF ablation for paroxysmal AF.

METHODS AND RESULTS

The primary efficacy endpoint documented AF recurrence ≥30 s was assessed by time-to-first-event analysis after a 90-day blanking period using repeated 7-day Holters. Secondary endpoints include acute success and procedural characteristics. Safety endpoints included procedural complications, stroke/transient ischaemic attack (TIA), tamponade, bleeding, and access site complications. Two hundred and eight patients underwent randomization and PVI (103 assigned to PVAC Gold, 105 to ST-CF). Acute success rates were 95% and 97% for PVAC Gold and ST-CF, respectively. At 12 months, AF recurrence was observed in 46.6% of the PVAC Gold group and in 26.2% of the ST-CF group [absolute efficacy difference 20.4% (95% confidence interval, CI 7.5-33.2%), hazard ratio 2.05 (95% CI 1.28-3.29), P = 0.003]. PVAC Gold had significantly shorter procedure and ablation times. Complication rates were 5.7% and 4.9% for PVAC Gold and ST-CF, respectively (P = 0.782).

CONCLUSION

In this multicentre randomized clinical trial, ablation with ST-CF and PVAC Gold ablation catheters non-inferiority for efficacy was not met. AF recurrence was significantly more frequent in the PVAC Gold group compared to single-tip contact force group. Both groups had similarly low rates of adverse events. PVAC Gold ablation had significantly shorter procedure and ablation times.

A prospective multi-site registry of real-world experience of catheter ablation for treatment of symptomatic paroxysmal and persistent atrial fibrillation (Real-AF): design and objectives

Purpose

Catheter ablation has become a mainstay therapy for atrial fibrillation (AF) with rapid innovation over the past decade. Variability in ablation techniques may impact efficiency, safety, and efficacy; and the ideal strategy is unknown. Real-world evidence assessing the impact of procedural variations across multiple operators may provide insight into these questions. The Real-world Experience of Catheter Ablation for the Treatment of Symptomatic Paroxysmal (PAF) and Persistent (PsAF) Atrial Fibrillation registry (Real-AF) is a multicenter prospective registry that will enroll patients at high volume centers, including academic institutions and private practices, with operators performing ablations primarily with low fluoroscopy when possible. The study will also evaluate the contribution of advent in technologies and workflows to real-world clinical outcomes.

Methods

Patients presenting at participating centers are screened for enrollment. Data are collected at the time of procedure, 10–12 weeks, and 12 months post procedure and include patient and detailed procedural characteristics, with short and long-term outcomes. Arrhythmia recurrences are monitored through standard of care practice which includes continuous rhythm monitoring at 6 and 12 months, event monitors as needed for routine care or symptoms suggestive of recurrence, EKG performed at every visit, and interrogation of implanted device or ILR when applicable.

Results

Enrollment began in January 2018 with a single site. Additional sites began enrollment in October 2019. Through May 2021, 1,243 patients underwent 1,269 procedures at 13 institutions. Our goal is to enroll 4000 patients.

Discussion

Real-AF’s multiple data sources and detailed procedural information, emphasis on high volume operators, inclusion of low fluoroscopy operators, and use of rigorous standardized follow-up methodology allow systematic documentation of clinical outcomes associated with changes in ablation workflow and technologies over time. Timely data sharing may enable real-time quality improvements in patient care and delivery.

Trial registration

Clinicaltrials.gov: NCT04088071 (registration date: September 12, 2019)

Supplementary Information

The online version contains supplementary material available at 10.1007/s10840-021-01031-w.

Assessing the Relationship of Applied Force and Ablation Duration on Lesion Size Using a Diamond Tip Catheter Ablation System

[Figure: see text].

Reduced esophageal heating in high-power short-duration atrial fibrillation ablation in the contact force catheter era

BACKGROUND

 Atrial fibrillation (AF) ablation is alternative treatment to medical therapy. Most feared complication is atrioesophageal fistula METHODS: Observational, retrospective analysis of consecutive 355 patients undergoing first AF ablation. Low-power long-duration (LPLD) group contained 158 patients, with 121 (76.58%) having paroxysmal AF who underwent ablation with power 20/30W (anterior and posterior left atrial wall), 17 mL/min flow, and a contact force of 10-30 g for 30 s. High-power short-duration group (HPSD) contained 197 patients, with 113 (57.36%) having paroxysmal AF who underwent ablation at 45/50W of power with a contact force of 8-15 g/10-20 g and a 35 mL/min flow rate for 6-8 s on the anterior and the posterior left atrial wall, respectively. Both groups had pulmonary veins isolated and atrial flutter was ablated when needed. For patients not in sinus rhythm, cardioversion was performed before ablation RESULTS: There were no complications. LPLD group: Left atrial time 118.74 min, total 145.32 min, radiofrequency time 4317.99s, X-ray 13.42 min, and elevation of luminal esophageal temperature (LET) in 132 (84.53%) patients. HPSD group: Left atrial time 72.16 min, total 93.76 min, radiofrequency time 1511.29s, X-ray 7.6 min, and LET elevation in only 75 (38.07%) patients. A markedly higher rate of first-pass isolation was observed in HPSD compared to LPLD, 77.16% versus 13.29%, respectively. Recurrence occurred in 64 (40.50%) and 32 (16.24%) in 28.45 and 22.35 months in LPLD and HPSD patients, respectively. In LPLD, 10 patients were submitted to endoscopy, and one (10%) had mild erythema and in HPSD, 13 performed the endoscopy, with two (15.38%) patients showing mild erythema CONCLUSION: HPSD technique compared to the LPLD technique showed significant reduced radiofrequency and fluoroscopy times, higher rate of first-pass isolation, lower recurrence rate, and esophageal temperature elevation and may also have a protective effect avoiding incidental esophageal injury due to these findings.

Efficacy and safety of novel temperature-controlled radiofrequency ablation system during pulmonary vein isolation in patients with paroxysmal atrial fibrillation: TRAC-AF study

BACKGROUND AND PURPOSE

Saline-irrigated radiofrequency ablation (RFA) for atrial fibrillation (AF) is limited by the absence of reliable thermal feedback limiting the utility of temperature monitoring for power titration. The DiamondTemp (DT) ablation catheter was designed to allow efficient temperature-controlled irrigated ablation. We sought to assess the 1-year clinical safety and efficacy of the DT catheter in treating drug-refractory paroxysmal AF.

METHODS

The TRAC-AF trial (NCT02821351) is a prospective, multi-center (n = 4), single-arm study which enrolled patients with symptomatic, drug-refractory, paroxysmal AF. Using the DT catheter, point-by-point ablation was performed around all pulmonary veins (PVs) to achieve PV isolation (PVI). Ablation was performed in a temperature-controlled mode (60 °C, max 50 W). Acute and chronic efficacy and safety was evaluated.

RESULTS

Seventy-one patients (age 69.9 ± 11.0 years; 60.6% male) were ablated using the DT catheter. The mean fluoroscopy and RF ablation times were 9.3 ± 6.1 min and 20.6 ± 8.9 min, respectively. Acute isolation of all PVs was achieved in 100% of patients, and freedom from AF after 1 year was 70.6%. There were no steam pops, char, or coagulum on the catheter tip after ablation. There were few serious procedure/device-related adverse events including a single case of cardiac tamponade (1.4%) and transient ischemic attack (1.4).

CONCLUSION

This first in man series demonstrates that temperature-controlled irrigated RFA with the DT catheter is efficient, safe, and effective in the treatment of paroxysmal AF. Randomized controlled trials are ongoing and will evaluate better the role of this catheter in relation to standard RFA.

TRIAL REGISTRATION

Registered on the site ClinicalTrials.gov January 2016 with identifier: NCT02821351.

Optimizing Durability in Radiofrequency Ablation of Atrial Fibrillation

Radiofrequency ablation (RFA) remains a highly effective therapy in the management of paroxysmal atrial fibrillation (PAF) and is an important therapeutic option in the management of persistent atrial fibrillation (PeAF) when clinically indicated. Lesion size is influenced by many parameters, which include those related to energy application (RFA power, temperature, and time), delivery mechanism (electrode size, orientation, and contact force), and the environment (blood flow and local tissue contact, stability, and local impedance). Successful durable RFA is dependent on achieving lesions that are reliably transmural and contiguous, whilst also avoiding injury to the surrounding structures. This review focuses on the variables that can be adjusted in connection with RFA to achieve long-lasting lesions that enable patients to derive the maximum sustained benefit from pulmonary vein isolation and additional lesion sets if utilized.

RF electrode-tissue coverage significantly influences steam pop incidence and lesion size

BACKGROUND

Steam pops are a rare complication associated with radiofrequency (RF) ablation and are hard to predict. The aim of this study was to assess the influence of coverage between the RF ablation electrode and cardiac tissue on steam pop incidence and lesion size.

METHODS AND RESULTS

An ex vivo model using porcine cardiac preparations and contact force sensing catheters was designed to perform RF ablations at different coverage levels between the RF electrode and cardiac tissue. During coverage level I, only the distal part of the ablation electrode was in contact with tissue. During coverage level II half of the ablation electrode, and during coverage level III the entire ablation electrode was embedded in tissue. RF applications (n = 60) at different coverage levels I-III were systematically performed using the same standardized ablation protocol. Ablations during coverage level III resulted in a significantly higher rate of steam pops (100%) when compared to ablations during coverage level II (10%) and coverage level I (0%), log rank p < .001. Coverage level I ablations resulted in significantly smaller lesion depths, diameters, and impedance drops when compared to higher coverage level ablations, p < .001. In the controlled ex vivo model, there was no difference in applied contact force or energy between different coverage levels.

CONCLUSIONS

The level of coverage between RF electrode, cardiac tissue, and the surrounding fluid significantly influenced the incidence of steam pops in an ex vivo setup. Larger coverage between RF electrode and tissue resulted in significantly larger lesion dimensions.

Pulmonary vein isolation in atrial fibrillation patients guided by a novel local impedance algorithm: 1-year outcome from the CHARISMA study

BACKGROUND

Highly localized impedance (LI) measurements during atrial fibrillation (AF) ablation have recently emerged as a viable real-time indicator of tissue characteristics and durability of the lesions created. We report the outcomes of acute and long-term clinical evaluation of the new DirectSense algorithm in AF ablation.

METHODS

Consecutive patients undergoing AF ablation were included in the CHARISMA registry. RF delivery was guided by the DirectSense algorithm, which records the magnitude and time-course of the impedance drop. The ablation endpoint was pulmonary vein isolation (PVI), as assessed by the entrance and exit block.

RESULTS

3556 point-by-point first-pass RF applications of >10 s duration were analyzed in 153 patients (mean age=59 ± 10 years, 70% men, 61% paroxysmal AF, 39% persistent AF). The mean baseline LI was 105 ± 15 Ω before ablation and 92 ± 12 Ω after ablation (p < .0001). Both absolute drops in LI and the time to LI drop (LI drop/τ) were greater at successful ablation sites (n = 3122, 88%) than at ineffective ablation sites (n = 434, 12%) (14 ± 8 Ω vs 6 ± 4 Ω, p < .0001 for LI; 0.73 [0.41-1.25] Ω/s vs. 0.35[0.22-0.59 Ω/s, p < .0001 for LI drop/τ). No major complications occurred during or after the procedures. All PVs had been successfully isolated. During a mean follow-up of 366 ± 130 days, 18 patients (11.8%) suffered an AF/atrial tachycardia recurrence after the 90-day blanking period.

CONCLUSION

The magnitude and time-course of the LI drop during RF delivery were associated with effective lesion formation. This ablation strategy for PVI guided by LI technology proved safe and effective and resulted in a very low rate of AF recurrence over 1-year follow-up.

Role of Indices Incorporating Power, Force and Time in AF Ablation: A Systematic Review of Literature

INTRODUCTION

Successful pulmonary vein isolation (PVI) for atrial fibrillation (AF) depends on the formation of durable transmural lesions. Recently, novel indices have emerged to guide lesion delivery. The aim of the systematic review of literature was to determine AF recurrence following ablation guided by indices incorporating force, power and time, and compare acute procedural outcomes and 12-month AF recurrence with ablation guided by contact force (CF) guided only.

METHODS

PubMed, EMBASE, and Web of Science Core Collection databases were searched on 27 January 2020 using the keywords; catheter ablation, ablation index (AI), lesion size index (LSI), contact force, atrial fibrillation.

RESULTS

After exclusions, seven studies were included in the analysis. AI-guided catheter ablation was associated with a 91% (n=5, 0.91 95% CI; 0.88-0.93) and 80% (n=5, 0.80, 95% CI; 0.77-0.84) freedom from AF at 12 months with and without the use of anti-arhythmic drugs respectively. As compared to CF guided ablation, AI-guided catheter ablation was associated with a 49% increase in successful first pass isolation (n=3; RR: 1.49, 95% CI; 1.38, 1.61), a 50% decrease in number of acute reconnections (n=4; RR: 0.50, 95% CI; 0.39-0.65) and a 22% (n=4, RR: 1.22, 95% CI; 1.10-1.35) increase in AF freedom without anti-arrhythmic drugs at 12 months.

CONCLUSIONS

Radiofrequency ablation guided by AI was associated with higher successful first pass isolation and lower rates of acute reconnection which translates to greater freedom from AF at 12 months [CRD42019131469].

Comparison of the lesion formation and safety in ex vivo porcine heart study: Using ThermoCool SmartTouch and ThermoCool SmartTouch-SF catheters

BACKGROUND

The study was performed to compare the efficacy and safety during radiofrequency ablation (RFA) using ThermoCool SmartTouch (ST) and ThermoCool SmartTouch-SF (STSF) catheters in the porcine heart.

METHODS AND RESULTS

RFA was performed on the porcine myocardium by using two irrigated ablation catheters. Three groups were divided based on the different contact forces (CFs): low contact force (LCF) (1-3 g), medium contact force (MCF) (5-10 g), and high contact force (HCF) (15-20 g). In each group, RFA was delivered at four power settings of 30, 40, 50, 60 W. At each power, RFA was applied to reach the target ablation index (AI) of 350, 450, and 500. Altogether, 360 RF lesions were created by using 72 ablation conditions. AI value was positively correlated with lesion size using ST and STSF catheters. At a fixed power, lesion dimensions significantly smaller in the LCF group, whereas did not differ between MCF and HCF groups. Furthermore, at a fixed CF, lesion dimensions increased with power set at 40 W compared with 30 W but decreased with high-power RF energy (50 and 60 W). Although the average lesion surface diameter and the maximum diameter was increased using the STSF catheter, there were no significant differences in LV between the two catheters. The steam pop provoked more frequently using ST catheter and showed a negative correlation with CF and positive correlation with high-power energy.

CONCLUSION

The STSF catheter is safer and equally effective in lesion formation compared with the ST catheter. LV was increased along with the early increase of CF and power, whereas a further increase of CF and power significantly reduces the lesion size.

Safety and Effectiveness of a Next-Generation Contact Force Catheter: Results of the TactiSense Trial

OBJECTIVES

The objective of this clinical trial was to evaluate the safety and effectiveness of the TactiCath Contact Force Ablation Catheter, Sensor Enabled (TactiCath SE) (Abbott, Abbott Park, Illinois) for the treatment of drug-refractory, symptomatic paroxysmal atrial fibrillation (PAF).

BACKGROUND

Catheter ablation of atrial fibrillation (AF) is an established therapy for the treatment of PAF. Ablation technology is evolving with the primary goals of improving efficacy and safety of the procedure.

METHODS

This was a multicenter single-arm trial evaluating a novel ablation catheter for the treatment of PAF. A total of 156 subjects were enrolled at 19 sites in the United States, Europe, and Australia. The primary safety endpoint was the rate of device- or procedure-related serious adverse events occurring within 7 days. The primary effectiveness endpoint was acute success defined as pulmonary vein isolation at 30 min after ablation. Two descriptive endpoints were prospectively captured: 1) 1-year freedom from recurrence of symptomatic AF, atrial flutter (AFL), and atrial tachycardia (AT) lasting ≥30 s without a new or increased dose of Class I/III antiarrhythmic drugs; and 2) 1-year drug-free success defined by the absence of any recurrent AF/AFL/AT lasting ≥30 s without using Class I/III antiarrhythmic drugs.

RESULTS

Primary safety events occurred in 4.7% of patients (95% confidence interval [CI]: 2.23% to 8.64%), and the procedure was acutely successful in 98.0% of patients (95% CI: 94.95% to 99.46%). According to Kaplan-Meier estimates at 1 year, 82.2% (95% CI: 74.7% to 87.6%) were free from symptomatic recurrence, and 1-year drug-free success was 68.2% (95% CI: 59.9% to 75.1%).

CONCLUSIONS

The TactiCath™ Contact Force Ablation Catheter, Sensor Enabled™ is safe and effective for the treatment of paroxysmal AF.

Predictors of recurrent atrial fibrillation following catheter ablation

INTRODUCTION

Atrial fibrillation (AF) is a complex and multi-factorial rhythm disorder. Catheter ablation is widely used for the management of AF. However, it is limited by relapse of the arrhythmia necessitating repeat procedures.

AREAS COVERED

This review aims to discuss the predictors of post-ablation recurrent AF including age, gender, genetic predisposition, AF type and duration, comorbidities, lifestyle factors, echocardiographic parameters of heart chambers, left atrial fibrosis and ablation strategies and targets. An extensive literature search was undertaken on PubMed and Google Scholar to obtain full texts of relevant AF-related articles.

EXPERT OPINION

Maintenance of stable sinus rhythm is the main intended outcome of AF ablation. Therefore, it is very crucial to identify the risk factors that may influence the ablation success. Most of these predictors such as comorbidities, ablation strategy and targets and lifestyle factors are either reversible or modifiable. Thus, not only the awareness of these known risk factors by both patients and their physicians but also future research to identify the unknown predictors are critical to optimize care in this multi-faceted morbidity.

What clinical trials of ablation for atrial fibrillation tell us - and what they do not

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in clinical practice. Radiofrequency and cryoballoon catheter ablation are therapeutic options in addition to antiarrhythmic drug therapy for the treatment of AF. Ablation is effective at reducing recurrent atrial arrhythmias and also in the reduction of AF burden. Besides arrhythmia control, improvement in quality of life and clinical outcomes are also desirable goals with AF treatment. Randomized clinical trials have evaluated ablation in several patient populations, including symptomatic patients as first-line or second-line therapy, asymptomatic patients, and patients with heart failure. These trials clarify the durability of ablation in arrhythmia control, clarify quality-of-life improvement, and identify patient populations in whom ablation may be expected to improve clinical outcomes. In this review, we summarize the major clinical trials involving ablation; discuss the strengths, weakness, and clinical implications of these trials; and highlight the knowledge gaps in our current understanding of AF ablation for future clinical studies.

A case report of pulmonary vein isolation with radiofrequency catheter using superior vena cava approach in patient with paroxysmal atrial fibrillation and inferior vena cava filter

Background

Transseptal puncture and pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF) are generally performed via the inferior vena cava (IVC). However, in cases where the IVC is inaccessible, a specific strategy may be needed.

Case summary

An 86-year-old woman with paroxysmal AF and an IVC filter in situ was referred to our hospital for ablation therapy. An IVC filter for pulmonary embolism and deep venous thrombosis had been implanted 15 years prior, therefore we selected a transoesophageal echocardiography (TOE)-guided transseptal puncture using a superior vena cava (SVC) approach. After the single transseptal puncture, we performed fast anatomical mapping, voltage mapping by multipolar mapping catheter, and then PVI by contact force-guided radiofrequency catheter using a steerable sheath. Following the ablation, bidirectional conduction block between the four pulmonary veins and the left atrium was confirmed by both radiofrequency and mapping catheter. No complications occurred and no recurrence of AF was documented in the 12 months after the procedure.

Discussion

When performing a transseptal puncture during AF ablation, an SVC approach, via access through the right internal jugular vein, enables the sheath to directly approach the left atrium without angulation and improves operability of the ablation catheter. Combining the use of general anaesthesia, TOE, a steerable sheath, and contact force-guided ablation may contribute to achieving minimally invasive PVI with a single transseptal puncture via an SVC approach.

Advanced fully integrated radiofrequency/optical-coherence-tomography irrigated catheter for atrial fibrillation ablation

The inability of current catheter ablation procedures to accurately monitor lesion formation limits their safety and efficacy. An advanced fully integrated radiofrequency (RF)/optical coherence tomography (OCT) ablation catheter is developed, which enables real-time monitoring during ablation. An OCT fiber array is especially designed, developed and integrated into an off-the-shelf irrigated RF ablation catheter. In-vitro experimental studies performed on poultry and ovine hearts demonstrate the ability of the integrated RF/OCT system to provide information on the quality and orientation of catheter/wall contact. Experimental results show that adipose tissue can be accurately identified from normal myocardial tissue with 94% accuracy and lesion formation is monitored with an overall accuracy of 93%. The ability to predict pop events is also demonstrated, with an accuracy of 86%.

Atrial Fibrillation (Part 2) - Catheter Ablation

More than 20 years since its initial use, catheter ablation has become a routinely performed procedure for the treatment of patients with atrial fibrillation (AF). Initially based on the electrical isolation of pulmonary veins in patients with paroxysmal AF, subsequent advances in the understanding of pathophysiology led to additional techniques not only to achieve better results, but also to treat patients with persistent forms of arrhythmia, as well as patients with structural heart disease and heart failure.

A Novel Temperature-Controlled Radiofrequency Catheter Ablation System Used to Treat Patients With Paroxysmal Atrial Fibrillation

OBJECTIVES

DIAMOND-AF (DiamondTemp™ Ablation System for the Treatment of Paroxysmal Atrial Fibrillation) was a prospective, multicenter, noninferiority, randomized trial that compared the safety and effectiveness of the DTA system versus those of a force-sensing RF ablation system (control) for the treatment of patients with drug-refractory, recurrent, symptomatic paroxysmal atrial fibrillation (AF).

BACKGROUND

Irrigated radiofrequency (RF) ablation catheters lose tissue temperature acuity, which is vital in assessing lesion formation. DiamondTemp Ablation (DTA) was designed to re-establish accurate tissue temperature measurements during ablation.

METHODS

A total of 482 patients with paroxysmal AF were randomized (239 DTA, 243 control) to undergo pulmonary vein isolation and were followed up at 23 sites. Patients were screened for disease progression, cardiac characteristics, and prior interventions. Primary endpoints were effectiveness (freedom from atrial arrhythmia recurrence) and safety (composite of procedure- and device-related serious adverse events).

RESULTS

The primary safety event rate was 3.3% in the DTA group versus 6.6% in the control group (p < 0.001 vs. 6.5% noninferiority margin). Primary effectiveness was met in 79.1% of DTA subjects and 75.7% of control subjects (p < 0.001 vs. -12.5% noninferiority margin). Secondary endpoint analysis found that off-drug effectiveness favored DTA compared with the control (142 [59.4%] vs. 120 [49.4%], respectively; p = 0.03). Total RF time and individual RF ablation duration were significantly shorter with less saline infused through the DTA catheter (p < 0.001). Both arms saw clinically meaningful improvements in quality of life at 12 months.

CONCLUSIONS

Safety and efficacy of the DTA system proved noninferior to force-sensing RF ablation in a paroxysmal AF population. Efficiencies were observed using DTA with shorter total RF times, individual RF ablation durations, and less saline infusion. (DiamondTemp™ Ablation System for the Treatment of Paroxysmal Atrial Fibrillation; NCT03334630).

High-density versus low-density mapping in ablation of atypical atrial flutter

PURPOSE

Ablation of atypical atrial flutter (AAFL) can be challenging. High-density (HD) mapping of ablation targets may potentially increase procedural success and freedom from recurrent AAFL. The objective of the present study was to explore whether employing HD mapping leads to a more favorable outcome in ablation of AAFL.

METHODS

We compared baseline and procedural characteristics, procedural success, safety and outcome of mapping and ablation of atypical flutter in three groups. (1) HD Grid catheter + the high-density electroanatomical mapping (EAM) system EnSite Precision; (2) standard 10-pole circular mapping catheter (CMC) + EnSite Precision; (3) CMC + the low-density EnSite Velocity EAM. Voltage and propagation maps were constructed.

RESULTS

Mapping of 142 AAFL in 82 patients was performed. Acute ablation success was 78%, 68%, and 51% in groups 1, 2, and 3 (p = 0.037 between group 1 and 3, non-significant between groups otherwise). Moreover, 8%, 27%, and 36% of flutters were unmappable in groups 1, 2, and 3, respectively (p < 0.05 between group 1 and both groups 2 and 3). AAFL recurrence at 1-year FU was 26%, 36%, and 62% in groups 1, 2, and 3 (p = 0.007 between groups 1 and 3, p = 0.05 between groups 2 and 3). AAFL-free survival was significantly higher in patients mapped with Precision than with Velocity (p = 0.011). No strokes or mortality occurred within 30 days.

CONCLUSIONS

Acute procedural success of ablation of atypical atrial flutter is higher and the number of unmappable flutters is lower using the HD Grid mapping catheter in combination with the high-density EnSite Precision system, as compared to a decapolar circular mapping catheter and the low-density EnSite Velocity EAM system. This may lead to increased freedom from recurrent AAFL at 1 year. HD mapping is safe.

High-power short-duration ablation of atrial fibrillation: A contemporary review

Catheter ablation using radiofrequency (RF) energy has been widely used to treat patients with atrial fibrillation (AF). The optimal levels of power and duration to increase the success rate while minimizing complications have not been fully established. Different centers continue to use various power protocols for catheter ablation of AF. Herein, we present a comprehensive review of the impact of power output on efficacy and safety of RF ablation for AF. High-power short-duration (HPSD) ablation can be performed safely with similar procedural efficacy as low-power long-duration ablation strategy. HPSD ablation has the potential to shorten procedural and RF times and create more durable and localized lesions.

[Management of acute complications during electrophysiological procedures]

Catheter ablation is an established treatment option in patients suffering from symptomatic cardiac arrhythmias. However, despite technical advances, catheter ablation is still associated with an incidence of severe complications of up to 5%. Therefore, electrophysiologists should be trained to prevent complications, maintain a high index of suspicion to recognize them quickly and implement necessary treatment strategies. This article reviews the incidence, risk factors, management and preventative strategies of the major complications associated with ablation procedures such as transseptal puncture-related risks, cardiac tamponade, aortic puncture and air embolism.

Surgical intervention for cardiac tamponade during atrial fibrillation ablation: who and when?-a single-center experience

INTRODUCTION

The critical decision between conservative therapy and surgical intervention to manage cardiac tamponade (CT) during atrial fibrillation (AF) ablation remains empirical. The aim of the study was to summarize the experience in management of CT during AF ablation to derive a proper management pathway.

METHODS

All patients with CT who underwent catheter ablation for AF in our center from 2013 to 2019 were included.

RESULTS

In total of 4887 patients, 32 (0.65%) patients occurred CT and received pericardiocentesis and immediate reversal of anticoagulation. All the CT patients were classified into three groups: rapid and uncontrollable bleeding who needed urgent surgical intervention (4/32), continuous bleeding (14/32), once pericardiocentesis, and no further bleeding (14/32). In the continuous bleeding group, the drainage volume in the first hour after pericardiocentesis was statistically related to surgical repair (p = 0.04) with a cutoff point of 970 ml (AUC 0.84, sensitivity 71.4%, specificity 100%, p = 0.04). During surgical repair, most of perforation sites were detected at superior anterior wall of left atrium close to right or left superior pulmonary vein antrum. No patient died of CT in our cohort.

CONCLUSIONS

Only a small proportion of patients with CT required surgical intervention during AF ablation. When pericardiocentesis was performed, if a drainage volume was more than 1000 ml in the first hour or bleeding was accelerated after an hour of observation, emergency surgical repair should be recommended.

Low complication rates using high power (45-50 W) for short duration for atrial fibrillation ablations

BACKGROUND

Many centers use radiofrequency (RF) energy at 25-35 W for 30-60 seconds. There is a safety concern about using higher power, especially on the posterior wall.

OBJECTIVE

The purpose of this study was to examine complication rates for atrial fibrillation (AF) ablations performed with high-power, short-duration RF energy.

METHODS

We examined the complication rates of 4 experienced centers performing AF ablations at RF powers from 45-50 W for 2-15 seconds per lesion. In total, 13,974 ablations were performed in 10,284 patients. On the posterior wall, 11,436 ablations used 45-50 W for 2-10 seconds, and 2538 ablations used power reduced to 35 W for 20 seconds. Esophageal temperature monitoring was used in 13,858 (99.2%).

RESULTS

Demographics were age 64 ± 11 years, male 68%, left atrial size 4.4 ± 0.7 cm, paroxysmal AF 37%, persistent AF 42%, longstanding AF 20%, antiarrhythmic drugs failed 1.4 ± 0.7, hypertension 54%, diabetes 15%, previous cerebrovascular accident/transient ischemic attack 7%, and CHA₂DS₂-VASc score 2.1 ± 1.4. Procedural time was 116 ± 41 minutes. Complications were death in 2 (0.014%; 1 due to stroke and 1 due to atrioesophageal fistula), pericardial tamponade in 33 (0.24%; 26 tapped, 7 surgical), strokes <48 hours in 6 (0.043%), strokes 48 hours-30 days in 6 (0.043%), pulmonary vein stenosis requiring intervention in 2 (0.014%), phrenic nerve paralysis in 2 (0.014%; both resolved), steam pops 2 (0.014%) without complications, and catheter char 0 (0.00%). There was 1 atrioesophageal fistula in 11,436 ablations using power 45-50 W on the posterior wall and 3 in 2538 ablated with 35 W on the posterior wall (P = .021), although 2 of the 3 had no esophageal monitoring during a fluoroless procedure.

CONCLUSION

AF ablations can be performed at 45-50 W for short durations with very low complication rates. High-power, short-duration ablations have the potential to shorten procedural and total RF times and create more localized and durable lesions.

Ablation catheter orientation: In vitro effects on lesion size and in vivo analysis during PVI for atrial fibrillation

BACKGROUND

Catheter-delivered radiofrequency (RF) lesion formation is a complex phenomenon, and few studies have explored the effect of catheter orientation on lesion size and catheter orientation behavior during pulmonary vein isolation (PVI) procedures. We evaluated the influence of catheter orientation on lesion dimensions in an in vitro experimental setting and investigated the catheter orientation behavior during PVI.

METHODS AND RESULTS

72 lesions were created in vitro on a porcine heart using a contact force catheter in a parallel, oblique, and perpendicular tip to tissue orientation. The superficial lesion length (SLL) increased shifting the catheter from perpendicular to parallel orientation. The intratissue absolute maximal lesion length (AML) was greater with an oblique catheter orientation. The lesion depth (LD) and the superficial lesion width (SLW) resulted similar with any orientation. Data from 21 PVI procedures in patients with paroxysmal atrial fibrillation using the "wide antral circumferential RF ablation" (WACA) technique were retrospectively analyzed. The mean contact angle among 1130 RF lesions was 28 ± 20°. A prevalent parallel orientation was noted in the anterior WACA segments, whereas it resulted more perpendicular in the posterior segments. Significant differences in catheter orientation between the three operators were found only in few WACA segments.

CONCLUSIONS

In an in vitro setting, catheter orientation affects SLL and AML, but not LD and SLW. During PVI procedures, catheter orientation resulted mostly parallel to the endocardium. Catheter orientation varied among different WACA segments, but only small differences were found between three operators when considering similar WACA segments.

Influence of ablation index on the incidence of cardiac tamponade complicating pulmonary vein isolation

BACKGROUND

Cardiac tamponade (CT) complicating pulmonary vein isolation (PVI) for atrial fibrillation (AF) is a complication that can increase morbidity and mortality. Radiofrequency energy is a known cause of CT. Ablation Index (AI) is a novel ablation quality marker. We hypothesized that use of AI reduces the incidence of CT.

METHODS

All AF procedures between 10/2014 and 06/2019 were included. Three ablation groups were defined: group A, RF ablation with non-contact force (CF) catheter; group B, RF ablation with CF catheter; and group C, RF ablation with CF catheter using AI. All episodes of CT were analyzed.

RESULTS

In total, 1222 consecutive AF patients underwent PVI. Group A consisted of 100 (8%) procedures, while group B included 432 (35%) procedures and group C 690 (57%) procedures. The overall risk for CT in all patients was 2.1% (26/1222). The risk in group A was 2.9% (3/100), in group B 2.5% (11/432), and in group C 1.7% (12/690), including all 1222 patients in the analysis (p < 0.05). Univariate analysis identified no further specific predictors for CT. With the exception of one patient (1/26; 3.8%), who needed surgical treatment, all CT could be successfully drained.

CONCLUSIONS

In a high-volume center, the use of AI decreased the risk of CT in patients undergoing RF ablation for AF by 32%.

Computer simulation study on the effect of electrode-tissue contact force on thermal lesion size in cardiac radiofrequency ablation

Purpose: In cardiac radiofrequency (RF) ablation, RF energy is often used to create a series of transmural lesions for blocking accessory conduction pathways. Electrode-tissue contact force (CF) is one of the key determinants of lesion formation during RF ablation. Low electrode-tissue CF is associated with ineffective RF lesion formation, whereas excessive CF may increase the risk of steam pop and perforation. By using finite element analysis, we studied lesion size and features at different values of electrode-tissue CF in cardiac RF ablation.Materials and methods: A computer-model-coupled electrode-tissue CF field, RF electric field, and thermal field were developed to study temperature distribution and lesion dimensions in cardiac tissue subjected to CF of 2, 5, 10, 20, 30, and 40 g with identical RF voltage and duration.Results: Increasing CF was associated with an increase in lesion depth, width, and cross-section area. The lesion cross-section area exhibited a linear increase, and the lesion width was significantly greater than lesion depth under the identical ablation condition. The relationship between CF value and lesion size is a power function: Lesion Size = a × CF^b (Lesion Depth = 3.17 × CF^0.14 and Lesion Width = 5.17 × CF^0.14).Conclusions: This study confirmed that CF is a major determinant of RF lesion size and that electrode-tissue CF affects the amount of power dissipated in tissue. At a constant RF voltage and application time, RF lesion size increases as CF increases.

Updated systematic review and meta-analysis of the impact of contact force sensing on the safety and efficacy of atrial fibrillation ablation: discrepancy between observational studies and randomized control trial data

Aims

Despite widespread adoption of contact force (CF) sensing technology in atrial fibrillation (AF) ablation, randomized data suggests lack of improvement in clinical outcomes. We aimed to assess the safety and efficacy of CF-guided vs. non CF-guided AF ablation.

Methods and results

Electronic databases were searched for randomized controlled trials (RCTs) and controlled observational studies (OS) comparing outcomes of AF ablation performed with vs. without CF guidance. The primary efficacy endpoint was freedom from AF at follow-up. The primary safety endpoint was major peri-procedural complications. Secondary endpoints included procedural, fluoroscopy, and ablation duration. Subgroup analyses were performed by AF type and study design. Nine RCTs (n = 903) and 26 OS (n = 8919) were included. Overall, CF guidance was associated with improved freedom from AF [relative risk (RR) 1.10; 95% confidence interval (CI) 1.02-1.18], and reduced total procedure duration [mean difference (MD) 15.33 min; 95% CI 6.98-23.68], ablation duration (MD 3.07 min; 95% CI 0.29-5.84), and fluoroscopy duration (MD 5.72 min; 95% CI 2.51-8.92). When restricted to RCTs however, CF guidance neither improved freedom from AF (RR 1.03; 95% CI 0.95-1.11), independent of AF type, nor did it reduce procedural, fluoroscopy, or ablation duration. Contact force guidance did not reduce the incidence of major peri-procedural complications (RR 0.89; 95% CI 0.64-1.24).

Conclusion

Meta-analysis of randomized data demonstrated that CF guidance does not improve the safety or efficacy of AF ablation, despite initial observational data showing dramatic improvement. Rigorous evaluation in randomized trials is needed before widespread adoption of new technologies.

Percutaneous Epicardial Ablation of Atrial Fibrillation

The observations afforded by epicardial mapping have not only increased the appreciation of distinct epicardial structures in the left atrium but also underscore the need to address the substrate transmurally. Although epicardial access and ablation have attendant risks, comparative studies with hybrid surgical approaches are lacking. In the search to find unifying mechanisms of atrial fibrillation, a conceptual shift that emphasizes the substrate in 3 dimensions, with the epicardium distinct from the endocardium, holds promise for future investigation and evolving therapeutic tools.

Oesophageal Probe Evaluation in Radiofrequency Ablation of Atrial Fibrillation (OPERA): results from a prospective randomized trial

Aims

The aim of the study was to determine the incidence of oesophageal lesions after radiofrequency ablation (RFA) of atrial fibrillation (AF) with or without the use of oesophageal temperature probes.

Methods and results

Two hundred patients were prospectively randomized into two groups: the OPERA+ group underwent RFA using oesophageal probes (SensiTherm™); the OPERA− group received RFA using fixed energy levels of 25 W at the posterior wall without an oesophageal probe. All patients underwent post-interventional endoscopy and Holter-electrocardiogram after 6 months. (Clinical.Trials.gov: NCT03246594). One hundred patients were randomized in OPERA+ and 100 patients in OPERA−. The drop-out rate was 10%. In total, 18/180 (10%) patients developed endoscopically diagnosed oesophageal lesions (EDEL). There was no difference between the groups with 10/90 (11%) EDEL in OPERA+ vs. 8/90 (9%) in OPERA− (P = 0.62). Despite the higher power delivered at the posterior wall in OPERA+ [28 ± 4 vs. 25 ± 2 W (P = 0.001)], the average EDEL size was equal [5.7 ± 2.6 vs. 4.5 ± 1.7 mm (P = 0.38)]. The peak temperature did not correlate with EDEL size. During follow-up, no patient died. Only one patient in OPERA− required a specific therapy for treatment of the lesion. Cumulative AF recurrence after 6 (3–13) months was 28/87 (32%) vs. 34/88 (39%), P = 0.541.

Conclusion

This first randomized study demonstrates that intraoesophageal temperature monitoring using the SensiTherm™ probe does not affect the probability of developing EDEL. The peak temperature measured by the thermoprobe seems not to correlate with the incidence of EDEL. Empiric energy reduction at the posterior wall did not affect the efficacy of the procedure.

Electrical Posterior Box Isolation in Persistent Atrial Fibrillation Changed to Paroxysmal Atrial Fibrillation: A Multicenter, Prospective, Randomized Study

BACKGROUND

Persistent atrial fibrillation (AF) can change to paroxysmal AF after antiarrhythmic drug medication and cardioversion. We investigated whether electrical posterior box isolation (POBI) may improve rhythm outcome of catheter ablation in those patient groups.

METHODS

We prospectively randomized 114 patients with persistent AF to paroxysmal AF (men, 75%; 59.8±9.9 years old) to circumferential pulmonary vein isolation (CPVI) alone group (n=57) and additional POBI group (n=57). Primary end point was AF recurrence after a single procedure, and secondary end points were recurrence pattern, cardioversion rate, and response to antiarrhythmic drugs.

RESULTS

After a mean follow-up of 23.8±10.2 months, the clinical recurrence rate did not significantly differ between the CPVI alone and additional POBI group (31.6% versus 28.1%; P=0.682; log-rank P=0.729). The recurrences as atrial tachycardias (5.3% versus 12.3%; P=0.134) and cardioversion rates (5.3% versus 10.5%; P=0.250) were not significantly different between the CPVI and POBI groups. At the final follow-up, sinus rhythm was maintained without antiarrhythmic drug in 52.6% of CPVI group and 59.6% of POBI group (P=0.450). No significant difference was found in major complication rates between the two groups (5.3% versus 1.8%; P=0.618), but the total ablation time was significantly longer in the POBI group (4187±952 versus 5337±1517 s; P<0.001).

CONCLUSIONS

In patients with persistent AF converted to paroxysmal AF by antiarrhythmic drug, the addition of POBI to CPVI did not improve the rhythm outcome of catheter ablation or influence overall safety, while leading to longer ablation time. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02176616.

The feasibility and effectiveness of a streamlined single-catheter approach for radiofrequency atrial fibrillation ablation

BACKGROUND

Catheter ablation for atrial fibrillation (AF) traditionally requires the use of circular mapping catheter (CMC) for pulmonary vein isolation (PVI). This study aimed to assess the feasibility and effectiveness of a CMC-free approach for AF ablation performed by a contiguous optimized (CLOSE) ablation protocol.

METHODS

A CLOSE-guided and CMC-free PVI protocol with a single transseptal puncture was attempted in 67 patients with AF. Left atrial (LA) CARTO voltage mapping was performed with the ablation catheter pre- and postablation to demonstrate entry block into the pulmonary veins, and pacing maneuvers were used to confirm exit block.

RESULTS

The CMC-free approach was successful in achieving PVI in 66 (98.5%) cases, with procedure time of 148 ± 32 minutes, ablation time of 27.5 ± 5.7 minutes, and fluoroscopy time of 7.8 ± 1.0 minutes. First-pass PVI was seen in 58(86.5%) patients, and pacing maneuvers successfully identified the residual gap in eight of the other nine cases. No complication was observed. At 12 months follow-up, 60 (89.6%) patients remained free from AF. The CMC-free approach resulted in a cost saving of £47,190.

CONCLUSION

A CMC-free CLOSE-guided PVI approach is feasible, safe, and cost-saving, and is associated with excellent clinical outcomes at 1 year.

Impact of epicardial fat on the duration of radiofrequency energy delivery during catheter ablation of atrial fibrillation

Aims

This study aimed to determine the impact of the volume of epicardial fat on the duration of radiofrequency (RF) energy delivery during the procedure of ablation of atrial fibrillation (AF).

Methods

The volume of epicardial fat was measured from spiral computerized tomography scan. The primary endpoint was the duration of RF delivery for pulmonary vein isolation (PVI), and the overall total duration of RF application. Secondary endpoint was conversion of AF to sinus rhythm or organisation of the arrhythmia after PVI.

Results

From March 2015 to May 2018, 222 patients (45.5% with persistent AF) underwent a first RF catheter ablation procedure for AF. The total duration of RF delivery, and the duration of RF delivery specifically for PVI were significantly associated with higher total volume of epicardial fat (p = 0.0002; p = 0.009 respectively), periatrial (p = 0.003; p = 0.045) and periventricular epicardial fat (p = 0.001; p = 0.012). In multivariate analysis, total epicardial fat volume was not significantly associated with total RF delivery duration (p = 0.743). For patients with arrhythmia at the time of the procedure, patients who achieved conversion or organisation of their arrhythmia after PVI had similar levels of total epicardial fat to those whose arrhythmia persisted (65 ± 35.2 vs 74.5 ± 31.2 ml; p = 0.192).

Conclusion

We observed a significant relation between total, periatrial, and periventricular epicardial fat, and the duration of RF delivery during ablation of AF. This relation was not significant by multivariate analysis meaning that epicardial fat may be a marker, but not an independent factor, of ablation complexity.

Randomized study defining the optimum target interlesion distance in ablation index-guided atrial fibrillation ablation

Aims

While the CLOSE protocol proposes a maximally tolerable interlesion distance (ILD) of 6 mm for ablation index ablation index-guided atrial fibrillation (AF) ablation, a target ILD has never been defined. This randomized study sought to establish a target ILD for ablation index-guided AF ablation.

Methods and results

Consecutive patients scheduled for first-time pulmonary vein (PV) isolation (PVI) were randomly assigned to ablation protocols with a target ILD of 5.0–6.0 mm or 3.0–4.0 mm, with the primary endpoint of first-pass PVI. In compliance with the CLOSE protocol, the maximum tolerated ILD was 6.0 mm in both study protocols. A target ablation index of ≥550 (anterior) or ≥400 (posterior) was defined for the ‘5–6 mm’ protocol and ≥500 (anterior) or ≥350 (posterior) for the ‘3–4 mm’ protocol. The study was terminated early for superiority of the ‘3–4 mm’ protocol. Forty-two consecutive patients were randomized and 84 ipsilateral PV pairs encircled according to the study protocol. First-pass PVI was accomplished in 35.0% of the ‘5–6 mm’ group and 90.9% of the ‘3–4 mm’ group (P &lt; 0.0001). Median ILD was 5.2 mm in the ‘5–6 mm’ group and 3.6 mm in the ‘3–4 mm’ group (P &lt; 0.0001). In line with the distinct ablation index targets, median ablation index was lower in the ‘3–4 mm’ group (416 vs. 452, P &lt; 0.0001). While mean procedure time was shorter in the ‘3–4 mm’ group (149 ± 27 vs. 167 ± 33min, P = 0.004), fluoroscopy times did not differ significantly (4.7 ± 2.2 vs. 5.1 ± 1.8 min, P = 0.565).

Conclusion

In ablation index-guided AF ablation, an ILD of 3.0–4.0 mm should be targeted rather than 5.0–6.0 mm. Moreover, the lower target ILD may allow for less extensive ablation at each given point.

Long-term clinical outcomes and prognostic indicators for focal impulse and rotor modulation guided ablation: A single-center observational study

BACKGROUND

Electrophysiologists have developed a computational mapping approach to localize sources that may perpetuate persistent atrial fibrillation (AF). Focal impulse and rotor modulation (FIRM)-guided ablation of these sources have produced variable results. The current study further assesses single-procedure success rates of FIRM-guided ablation for preventing AF or atrial tachyarrhythmia recurrence and analyzes different baseline characteristics as prognostic indicators for individuals experiencing these undesired outcomes.

METHODS

Seventy-one consecutive patients (mean age 64.58 ± 9.05 years and 36.6% female) with drug-refractory persistent AF with and without prior history of pulmonary vein antral isolation (PVAI) underwent FIRM-guided ablation. Patients without prior history of PVAI underwent FIRM-guided ablation in addition to de novo PVAI. Patients with prior history of PVAI had the pulmonary veins reassessed at the time of FIRM-guided ablation for reconnection as well as re-isolation, when necessary. These patients were then prospectively followed for AF and atrial tachyarrhythmia recurrence.

RESULTS

FIRM analysis revealed rotors in the right atrium in 66.2% (1.77 ± 1.53 mean rotors per patient) and in the left atrium in 85.9% (2.65 ± 1.52 mean rotors per patient) of patients analyzed in the current study. After a single FIRM-guided ablation procedure, AF and atrial tachyarrhythmia recurrence was demonstrated in 21.1% (15/71) and 33.8% (24/71) of patients, respectively. The entire cohort of patients were followed for a mean duration of 23.20 ± 8.38 months with the mean time to AF recurrence found to be 12.35 ± 10.44 months. Furthermore, valvular heart disease (i.e. moderate mitral or tricuspid regurgitation) was found to be a statistically significant independent predictor for AF recurrence following FIRM-guided ablation (p = .033).

CONCLUSIONS

FIRM-guided ablation in combination with PVAI is a suitable and effective approach for symptomatic individuals with drug-refractory persistent AF with and without prior history of PVAI. Randomized controlled studies are warranted.

The Cryoballoon vs Irrigated Radiofrequency Catheter Ablation (CIRCA-DOSE) Study Results in Context

The Cryoballoon vs Irrigated Radiofrequency Catheter Ablation: Double Short vs Standard Exposure Duration (CIRCA-DOSE) study was a multicentre, randomised, single-blinded trial that compared contact-force radiofrequency ablation and two different regimens of cryoballoon ablation. All patients received an implantable cardiac monitor for the purpose of continuous rhythm monitoring, with all arrhythmia events undergoing independent adjudication by a committee blinded to treatment allocation. The study demonstrated there were no significant differences between contact-force radiofrequency ablation and cryoballoon ablation with respect to recurrence of any atrial tachyarrhythmia, symptomatic atrial tachyarrhythmia, asymptomatic AF, symptomatic AF or AF burden. While the results of the CIRCA-DOSE study are reviewed here, this article focuses on considerations around the design of the study and places the observed outcomes in context.

Balloon-Based Ablation Technologies

Pulmonary vein isolation (PVI) is widely accepted as the mainstay of interventional treatment of atrial fibrillation. Ablation with radiofrequency (RF) point-by-point catheters is highly operator dependent and may fail because of ineffective lesions or gaps. Several balloon-based catheter ablation technologies have emerged as an alternative to effect PVI. Cryoballoon ablation is widely used, and current iterations of the technology show comparable acute and long-term efficacy to RF ablation. Techniques such as time to isolation have emerged to improve efficacy and safety. Laser balloon is a highly compliant variably sized balloon that has been validated as an effective strategy for PVI.

Lattice-Tip Focal Ablation Catheter That Toggles Between Radiofrequency and Pulsed Field Energy to Treat Atrial Fibrillation

Background:

The tissue selectivity of pulsed field ablation (PFA) provides safety advantages over radiofrequency ablation in treating atrial fibrillation. One-shot PFA catheters have been shown capable of performing pulmonary vein isolation, but not flexible lesion sets such as linear lesions. A novel lattice-tip ablation catheter with a compressible 9-mm nitinol tip is able to deliver either focal radiofrequency ablation or PFA lesions, each in 2 to 5 s.

Methods:

In a 3-center, single-arm, first-in-human trial, the 7.5F lattice catheter was used with a custom mapping system to treat paroxysmal or persistent atrial fibrillation. Toggling between energy sources, point-by-point pulmonary vein encirclement was performed using biphasic PFA posteriorly and either temperature-controlled irrigated radiofrequency ablation or PFA anteriorly (RF/PF or PF/PF, respectively). Linear lesions were created using either PFA or radiofrequency ablation.

Results:

The 76-patient cohort included 55 paroxysmal and 21 persistent atrial fibrillation patients undergoing either RF/PF (40 patients) or PF/PF (36 patients) ablation. The pulmonary vein isolation therapy duration time (transpiring from first to last lesion) was 22.6±8.3 min/patient, with a mean of 50.1 RF/PF lesions/patient. Linear lesions included 14 mitral (4 RF/2 RF+PF/8 PF), 34 left atrium roof (12 RF/22 PF), and 44 cavotricuspid isthmus (36 RF/8 PF) lines, with therapy duration times of 5.1±3.5, 1.8±2.3, and 2.4±2.1 min/patient, respectively. All lesion sets were acutely successful, using 4.7±3.5 minutes of fluoroscopy. There were no device-related complications, including no strokes. Postprocedure esophagogastroduodenoscopy revealed minor mucosal thermal injury in 2 of 36 RF/PF and 0 of 24 PF/PF patients. Postprocedure brain magnetic resonance imaging revealed diffusion-weighted imaging+/fluid-attenuated inversion recovery- and diffusion-weighted imaging+/fluid-attenuated inversion recovery+ asymptomatic lesions in 5 and 3 of 51 patients, respectively.

Conclusions:

A novel lattice-tip catheter could safely and rapidly ablate atrial fibrillation using either a combined RF/PF approach (capitalizing on the safety of PFA and the years of experience with radiofrequency energy) or an entirely PF approach.

Registration:

URL: https://www.clinicaltrials.gov ; Unique identifiers: NCT04141007 and NCT04194307.

Current Status of Esophageal Protection

Catheter ablation of atrial fibrillation necessitates ablation on the posterior left atrium. The anterior esophagus touches the posterior left atrium, although its course is highly variable. The proximity of the left atrium to the esophagus confers risk of injury with radiofrequency and cryoablation owing to the heat transfer that occurs with thermal ablation. Early detection of esophageal temperature changes with probes may decrease the extent of damage to the esophagus, but evidence is mixed. Avoiding ablation on the esophagus with esophageal deviation and modifying ablation approaches may decrease the risk of injury.

Procedural outcomes and learning curve of cardiac arrhythmias catheter ablation using remote magnetic navigation: Experience from a large-scale single-center study

Background

Remote magnetic navigation (RMN)‐guided ablation has become an inspiring method of catheter ablation for tachyarrhythmias.

Hypothesis

Data from a large‐scale single center may provide further insight into the safety of and the learning curve for RMN‐guided ablation.

Methods

A total of 1003 catheter ablation procedures using RMN for conditions including supraventricular ventricular tachycardia, atrial tachyarrhythmias, and premature ventricular contraction/ventricular tachycardia (PVC/VT) were retrospectively analyzed from an ablation registry. Procedural outcomes, including procedure time, mapping time, X‐ray time, and RF time, were assessed. The complications were classified into two categories: major and minor. A subanalysis was used to illustrate the learning curve of RMN‐guided ablation by assessing procedure time and total X‐ray time of 502 atrial fibrillation (AF) ablation procedures.

Results

Among these procedures, 556 (55.4%) were AF and 290 (28.9%) were PVC/VT. Electrical pulmonary vein isolation was achieved in 99.0% of AF procedures, and acute success reached 90.3% in PVC/VT procedures. The overall complication rate was 0.5%. In the subanalysis of AF procedures, the overall procedure time and X‐ray time of procedures were short (125.9 ± 54.6 and 5.3 ± 3.9 minutes, respectively) and proceeded to decrease from the initial 30 procedures to about 300 procedures, where the learning curve reached plateau, demonstrating maximum procedure efficiency.

Conclusions

RMN‐guided ablation is safe, as verified by very low overall complication rate and reduced X‐ray time. In our study, even the first AF procedures had a relatively low procedure time and total X‐ray time, and procedure efficiency improved during the learning curve.

Contact force sensing in ablation of ventricular arrhythmias using a 56-hole open-irrigation catheter: a propensity-matched analysis

Purpose

The effect of adding contact force (CF) sensing to 56-hole tip irrigation in ventricular arrhythmia (VA) ablation has not been previously studied. We aimed to compare outcomes with and without CF sensing in VA ablation using a 56-hole radiofrequency (RF) catheter.

Methods

A total of 164 patients who underwent first-time VA ablation using Thermocool SmartTouch Surround Flow (TC-STSF) catheter (Biosense-Webster, Diamond Bar, CA, USA) were propensity-matched in a 1:1 fashion to 164 patients who had first-time ablation using Thermocool Surround Flow (TC-SF) catheter. Patients were matched for age, gender, cardiac aetiology, ejection fraction and approach. Acute success, complications and long-term follow-up were compared.

Results

There was no difference between procedures utilising either TC-SF or TC-STSF in acute success (TC-SF: 134/164 (82%), TC-STSF: 141/164 (86%), p = 0.3), complications (TC-SF: 11/164 (6.7%), TC-STSF: 11/164 (6.7%), p = 1.0) or VA-free survival (TC-SF: mean arrhythmia-free survival time = 5.9 years, 95% CI = 5.4–6.4, TC-STSF: mean = 3.2 years, 95% CI = 3–3.5, log-rank p = 0.74). Fluoroscopy time was longer in normal hearts with TC-SF (19 min, IQR: 14–30) than TC-STSF (14 min, IQR: 8–25; p = 0.04).

Conclusion

Both TC-SF and TC-STSF catheters are safe and effective in treating VAs. The use of CF sensing catheters did not improve safety or acute and long-term outcomes, but reduced fluoroscopy time in normal heart VA.