Use of contact force sensing technology during radiofrequency ablation reduces recurrence of atrial fibrillation: A systematic review and meta-analysis

Duration of atrial fibrillation persistence: Implications for recurrence risk after catheter ablation and efficacy of additional substrate ablation

BACKGROUND

The optimal duration of atrial fibrillation (AF) persistence for predicting poor outcomes after catheter ablation of long-standing AF (LsAF) and the best ablation strategy for these patients remain unclear.

OBJECTIVE

We aimed to assess the impact of the duration of AF persistence on outcomes after catheter ablation of AF.

METHODS

We analyzed the Efficacy of Pulmonary Vein Isolation Alone in Patients with Persistent Atrial Fibrillation (EARNEST-PVI) trial data comparing pulmonary vein isolation (PVI) alone (PVI-alone) with additional linear ablation or defragmentation (PVI-plus) in persistent AF (PerAF). Patients who received catheter ablation by contact force-sensing catheter were enrolled in the study. In patients with LsAF, the optimal cutoff duration of AF persistence was evaluated. With use of the threshold, patients with LsAF were divided into 2 groups and compared with PerAF <1 year for arrhythmia-free survival after a 3-month blanking period.

RESULTS

The optimal cutoff duration was 2.4 years. Of 458 patients, arrhythmia-free survival rates for LsAF 1-2.4 years were comparable to those of PerAF (hazard ratio [HR], 1.01; 95% CI, 0.67-1.52). However, LsAF >2.4 years had a higher recurrence risk than PerAF (HR, 2.22; 95% CI, 1.42-3.47). In LsAF >2.4 years, the PVI-plus strategy showed advantages over the PVI-alone strategy (HR, 0.36; 95% CI, 0.14-0.89). However, the interaction effect between LsAF 1-2.4 years and LsAF >2.4 years did not reach statistical significance (P = .116).

CONCLUSION

Whereas LsAF 1-2.4 years has similar outcomes to those of PerAF, LsAF >2.4 years was linked to higher arrhythmia recurrence risks. For LsAF >2.4 years, the PVI-plus strategy showed a potential to be superior to the PVI-alone strategy.

Contact force sensing manual catheter versus remote magnetic navigation ablation of atrial fibrillation: a single-center comparison

BACKGROUND

Data comparing remote magnetic catheter navigation (RMN) with manual catheter navigation in combination with contact force sensing (MCN-CF) ablation of atrial fibrillation (AF) is lacking. The primary aim of the present retrospective comparative study was to compare the outcome of RMN versus (vs.) MCN-CF ablation of AF with regards to AF recurrence. Secondary aim was to analyze periprocedural risk, ablation characteristics and repeat procedures.

METHODS

We retrospectively analyzed 452 patients undergoing a total of 605 ablations of AF: 180 patients were ablated using RMN, 272 using MCN-CF.

RESULTS

Except body mass index there was no significant difference between groups at baseline. After a mean 1.6 ± 1.6 years of follow-up and 1.3 ± 0.4 procedures, 81% of the patients in the MCN-CF group remained free of AF recurrence compared to 53% in the RMN group (P < 0.001). After analysis of 153 repeat ablations (83 MCN-RF vs. 70 RMN; P = 0.18), there was a significantly higher reconnection rate of pulmonary veins after RMN ablation (P < 0.001). In multivariable Cox-regression analysis, RMN ablation (P < 0.001) and left atrial diameter (P = 0.013) was an independent risk factor for AF recurrence. Procedure time, radiofrequency application time and total fluoroscopy time and fluoroscopy dose were higher in the RMN group without difference in total number of ablation points. Complication rates did not differ significantly between groups (P = 0.722).

CONCLUSIONS

In our retrospective comparative study, the AF recurrence rate and pulmonary vein reconnection rate is significantly lower with more favorable procedural characteristics and similar complication rate utilizing MCN-CF compared to RMN.

Local impedance and contact force guidance to predict successful cavotricuspid isthmus ablation with a zero-fluoroscopy approach

Introduction

A new technology capable of monitoring local impedance (LI) and contact force (CF) has recently been developed. At the same time, there is growing concern regarding catheter ablation performed under fluoroscopy guidance, due to its harmful effects for both patients and practitioners. The aim of this study was to assess the safety and effectiveness of zero-fluoroscopy cavotricuspid isthmus (CTI) ablation monitoring LI drop and CF as well as to elucidate if these parameters can predict successful radiofrequency (RF) applications in CTI ablation.

Methods

We conducted a prospective observational study recruiting 50 consecutive patients who underwent CTI ablation. A zero-fluoroscopy approach guided by the combination of LI drop and CF was performed. In each RF application, CF and LI drop were monitored. A 6-month follow-up visit was scheduled to assess recurrences.

Results

A total of 767 first-pass RF applications were evaluated in 50 patients. First-pass effective RF applications were associated with greater LI drops: absolute LI drops (30.05 ± 6.23 Ω vs. 25.01 ± 5.95 Ω), p = 0.004) and relative LI drops (-23.3 ± 4.9% vs. -18.3 ± 5.6%, p = 0.0005). RF applications with a CF between 5 and 15 grams achieved a higher LI drop compared to those with a CF below 5 grams (29.4 ± 8.76 Ω vs. 24.8 ± 8.18 Ω, p < 0.0003). However, there were no significant differences in LI drop between RF applications with a CF between 5 and 15 grams and those with a CF beyond 15 grams (29.4 ± 8.76 Ω vs. 31.2 ± 9.81 Ω, p = 0.19). CF by itself, without considering LI drop, did not predict effective RF applications (12.3 ± 7.54 g vs. 11.18 ± 5.18 g, p = 0.545). Successful CTI ablation guided by a zero-fluoroscopy approach was achieved in all patients. Only one patient experienced a recurrence during the 6-month follow-up.

Conclusions

LI drop (absolute and relative values) appears to be a good predictor of successful RF applications to achieve CTI conduction block. The optimal CF to achieve a good LI drop is between 5 and 15 g. A zero-fluoroscopy approach guided by LI and CF was feasible, effective, and safe.

Methods and techniques for increasing the safety and efficacy of pulmonary vein isolation in patients with atrial fibrillation

The most common type of sustained arrhythmia is atrial fibrillation (AF). Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation for atrial fibrillation, which has emerged as the primary therapeutic strategy for atrial fibrillation patients. Unfortunately, about one-third of patients experience recurrent atrial arrhythmias after the procedure.

A novel stepwise catheter ablation method of the mitral isthmus for persistent atrial fibrillation: efficacy and reproducibility

BACKGROUND

Ethanol infusion of the vein of Marshall (EI-VOM) has been widely used to facilitate mitral isthmus (MI) ablation. According to the literature, the success rate of achieving a bidirectional conduction block across the MI ranges from 51 to 96%, with no standardized strategy or method available for cardiac electrophysiologists.

OBJECTIVES

This study aimed to introduce and evaluate a novel ablation method of MI.

METHODS

Consecutive patients with persistent atrial fibrillation (PeAF) that underwent catheter ablation were included. The MI ablation procedure followed a stepwise approach. In step 1, ethanol infusion of the vein of Marshall (EI-VOM) was performed. In step 2, a "V-shape" endocardial linear ablation connecting the left inferior pulmonary vein (LIPV) to mitral annulus (MA) was performed. In step 3, earliest activation sites(EASs) near the ablation line were identified using activation mapping followed by reinforced ablation. In step 4, precise epicardial ablation was performed, with the catheter introduced into the coronary sinus(CS) to target key ablation targets (KATs).

RESULTS

135 patients with PeAF underwent catheter ablation with the stepwise ablation method adopted in 119 cases. Bidirectional conduction blocks were achieved in 117 patients (98.3%). The block rates of every step were 0%, 58.0%, 44.0%, and 92.9%, and the cumulative block rates for the four steps were 0%, 58.0%, 76.5%, and 98.3%, respectively. No patient experienced fatal complications.

CONCLUSIONS

Our novel stepwise catheter ablation method for MI yielded a high bidirectional block rate with high reproducibility.

Catheter-Based Electroporation: A Novel Technique for Catheter Ablation of Cardiac Arrhythmias

Catheter ablation of arrhythmias is now standard of care in invasive electrophysiology. Current ablation strategies are based on the use of thermal energy. With continuous efforts to optimize thermal energy delivery, effectiveness has greatly improved; however, safety concerns persist. This review focuses on a novel ablation technology, irreversible electroporation (IRE), also known as pulsed-field ablation which may be a safer alternative for arrhythmia management. Pulsed-field ablation is thought to be a nonthermal ablation that applies short-duration high-voltage electrical fields to ablate myocardial tissue with high selectivity and durability while sparing important neighboring structures such as the esophagus and phrenic nerves. There are multiple ongoing studies investigating the potential superior outcomes of IRE compared to radiofrequency ablation in treating patients with atrial and ventricular arrhythmias. In this review, we describe the current evidence of preclinical and clinical trials that have shown promising results of catheter-based IRE.

Short and Long-Term Outcomes of Lesion Index-Guided High-Power Short-Duration Approach for Atrial Fibrillation Ablation

High-power short-duration (HPSD) ablation is an increasingly used ablation strategy for pulmonary vein isolation (PVI) procedures, but Lesion Index (LSI)-guided HPSD radiofrequency (RF) applications have not been described in this clinical setting. We evaluated the procedural efficiency and safety of an LSI-guided HPSD strategy for atrial fibrillation (AF) ablation. Paroxysmal and persistent AF patients scheduled for AF ablation were prospectively enrolled and divided into two groups, according to the ablation power used (≥45 W for the LSI-HP Group and ≤40 W for the LSI-LP group). All patients underwent only PVI LSI-guided ablation (5.5 to 6 anteriorly; 5 to 5.5 superiorly, 4.5 to 5 posteriorly) with a point-by-point strategy and an inter-lesion distance <6 mm. Forty-six patients with AF (25 in the LSI-HP Group vs 21 in the LSI-LP Group)-59% paroxysmal, 78% male, with low-intermediate CHA2DS2-Vasc scores (2 [1-3]), a preserved ejection fraction (65 ± 6%) and a mean left atrial index volume of 39 ± 13 mL/m2 were prospectively enrolled. Baseline clinical characteristics were comparable between groups. PVI was successful in all patients. The RF time (29 (23-37) vs. 49 (41-53) min, p < 0.001), total procedure time (131 (126-145) vs. 155 (139-203) min, p = 0.007) and fluoroscopy time (12 (10-18) vs. 21 (16-26) min, p = 0.001) were significantly lower in the LSI-HP Group. No complications or steam pops were seen in either group. LSI-HP AF ablation significantly improved procedural efficiency-reducing ablation time, total procedural duration, and fluoroscopy use, while maintaining a comparable safety profile to lower-power procedures.

A Novel Catheter Distal Contact Force Sensing for Cardiac Ablation Based on Fiber Bragg Grating with Temperature Compensation

OBJECTIVE

To accurately achieve distal contact force, a novel temperature-compensated sensor is developed and integrated into an atrial fibrillation (AF) ablation catheter.

METHODS

A dual elastomer-based dual FBGs structure is used to differentiate the strain on the two FBGs to achieve temperature compensation, and the design is optimized and validated by finite element simulation.

RESULTS

The designed sensor has a sensitivity of 90.5 pm/N, resolution of 0.01 N, and root-mean-square error (RMSE) of 0.02 N and 0.04 N for dynamic force loading and temperature compensation, respectively, and can stably measure distal contact forces with temperature disturbances.

CONCLUSION

Due to the advantages, i.e., simple structure, easy assembly, low cost, and good robustness, the proposed sensor is suitable for industrial mass production.

Pulsed Electrical Field in Arrhythmia Treatment: Current Status and Future Directions

Pulsed electrical field (PEF) ablation is a promising novel ablation modality for the treatment of arrhythmia, especially for atrial fibrillation(AF). It relies on electroporation inducing cellular permeabilization by the formation of pores in cell membranes, potentially resulting in cell death. Due to its' non-thermal nature and remarkable tissue selectivity, PEF ablation has be expected largely to replace conventional energy sources, such as radiofrequency (RF) and cryothermy. Up to now, the results in almost all clinical studies of PFA for AF ablation are optimistic, both in terms of effectiveness and safety. The possibility of clinical application of this technology to ventricular tachycardia(VT) has also been supported by several animal models. In this review, we aim to give an overview of the mechanism and technical progress of PFA in cardiac arrhythmia treatment. This article is protected by copyright. All rights reserved.

Current Understanding of Atrial Fibrillation Recurrence After Atrial Fibrillation Ablation: From Pulmonary Vein to Epicardium

Recurrence of atrial fibrillation (AF) after catheter ablation is common, with pulmonary vein (PV) reconnection considered the most likely cause. However, technologies such as contact force-sensing, irrigated catheters, and ablation index (AI)-guided ablation strategies have resulted in more durable PV isolation. As a result, it is difficult to predict which patients will develop AF recurrence despite durable PV isolation, with evolving non-PV atrial substrates thought to be a key contributor to late recurrences. Deciphering the complex mechanisms of AF recurrence beyond the cornerstone of PV isolation therefore remains challenging. Recently, there have been several important advances that may lead to better understanding and treatment of this challenging clinical entity: percutaneous epicardial access and mapping, late gadolinium enhancement magnetic resonance imaging (LGE-MRI), improvements in high-resolution electroanatomic mapping, and new ablation energy sources, specifically pulsed-field ablation. This review aims to synthesize the current literature in an effort to better understand arrhythmia mechanisms and treatment targets in patients with AF/Atrial tachycardia (AT) recurrence post-ablation. This article is protected by copyright. All rights reserved.

Economic Evaluation of Catheter Ablation Versus Medical Therapy for the Treatment of Atrial Fibrillation from the Perspective of the UK

Randomised evidence supports an early rhythm control strategy as treatment for AF, and catheter ablation outperforms medical therapy in terms of effectiveness when studied as first- and second-line treatment. Despite evidence consistently showing that catheter ablation treatment is superior to medical therapy in most AF patients, only a small proportion receive ablation, in some cases after a prolonged trial of ineffective medical therapy. Health economics research in electrophysiology remains limited but is recognised as being important in influencing positive change to ensure early access to ablation services for all eligible patients. Such information has informed the updated recommendations from the recently published National Institute for Health and Care Excellence clinical guideline on the diagnosis and management of AF, but increased awareness is needed to drive real-world adoption and to ensure patients are quickly referred to specialists. In this article, economic evaluations of catheter ablation versus medical therapy are reviewed.

Catheter ablation using advanced porous tip contact force–sensing radiofrequency catheter: Impact on health care utilization among patients with persistent atrial fibrillation

Background

Catheter ablation (CA) is an effective treatment for patients with persistent atrial fibrillation (PsAF); however, little is known about its impact on health care utilization for patients with PsAF. The ThermoCool SmartTouch SF (STSF) catheter (Biosense Webster) incorporates an advanced porous tip and contact force–sensing technology.

Objective

The purpose of this study was to determine health care utilization among patients with PsAF who underwent ablation with the STSF catheter.

Methods

A retrospective cohort study using the Premier Healthcare Database identified patients with PsAF undergoing CA with the STSF catheter in inpatient and outpatient settings. The proportion of patients experiencing AF-related inpatient admissions, outpatient admissions, emergency department (ED) visits, electrical cardioversion, and a composite outcome in the 12 months pre- vs postablation were compared using the McNemar test. Subanalyses were performed on study outcomes by race/ethnicity.

Results

The final sample included 3077 patients (mean age 65.9 years; 31.7% female). Among patients with PsAF undergoing ablation with the STSF catheter, relative reductions in health care utilization in the 12 months post- vs preablation included 55.3% in AF-related inpatient admissions (P <.0001), 38.9% in outpatient admissions (P <.0001), 52.4% in ED visits (P <.0001), and 61.2% in electrical cardioversions (P <.0001). Composite outcome utilization in the 12 months post- vs preablation declined by 40.2% (P <.0001) for the overall cohort, 40.0% for White patients (P <.0001), 52.2% for Black patients (P <.0001), and 50.1% for Asian patients (P = .032).

Conclusion

Significant improvements in health care utilization were observed among PsAF patients who underwent ablation using the STSF catheter. Improvements were particularly marked in underrepresented racial and ethnic groups.

Extracellular Vesicles in Cardiovascular Diseases: Diagnosis and Therapy

Cardiovascular diseases (CVDs) are the leading cause of global mortality. Therapy of CVDs is still a great challenge since many advanced therapies have been developed. Multiple cell types produce nano-sized extracellular vesicles (EVs), including cardiovascular system-related cells and stem cells. Compelling evidence reveals that EVs are associated with the pathophysiological processes of CVDs. Recently researches focus on the clinical transformation in EVs-based diagnosis, prognosis, therapies, and drug delivery systems. In this review, we firstly discuss the current knowledge about the biophysical properties and biological components of EVs. Secondly, we will focus on the functions of EVs on CVDs, and outline the latest advances of EVs as prognostic and diagnostic biomarkers, and therapeutic agents. Finally, we will introduce the specific application of EVs as a novel drug delivery system and its application in CVDs therapy. Specific attention will be paid to summarize the perspectives, challenges, and applications on EVs’ clinical and industrial transformation.

Impact of Contact Force-Sensing Catheters on Fluoroscopy Time in Interventional Electrophysiology: A European Survey

This multicenter European survey systematically evaluated the impact of using contact force-sensing catheters (CFSCs) on fluoroscopy and procedure time in interventional electrophysiology. Data from 25 participating centers were collected and analyzed, also considering important confounders. With the use of CFSCs, fluoroscopy time was reduced for right- and left-sided atrial ablations (median −6.4 to −9.6 min, p < 0.001 for both groups), whereas no such effect could be found for ventricular ablations. Moreover, the use of CFSCs was associated with an increase in procedure time for right-sided atrial and ventricular ablations (median +26.0 and +44.0 min, respectively, p < 0.001 for both groups), but not for left-sided atrial ablations. These findings were confirmed independent of career level and operator volume, except for very highly experienced electrophysiologists, in whom the effect was blunted. In the subset of pulmonary vein isolations (PVIs), CFSCs were shown to reduce both fluoroscopy and procedure time. In conclusion, the use of CFSCs was associated with a reduced fluoroscopy time for atrial ablations and an increased procedure time for right atrial and ventricular ablations. These effects were virtually independent of the operator experience and caseload. When considering only PVIs as an important subset, CFSCs were shown to reduce both fluoroscopy and procedure time.

Local impedance measurements during contact force‐guided cavotricuspid isthmus ablation for predicting an effective radiofrequency ablation

Background

An ablation catheter capable of contact force (CF) and local impedance (LI) monitoring (IntellaNav StablePoint, Boston Scientific) has been recently launched. We evaluated the relationship between the CF and LI values during radiofrequency catheter ablation (RFCA) along the cavotricuspid isthmus (CTI).

Methods

Fifty consecutive subjects who underwent a CTI‐RFCA using IntellaNav StablePoint catheters were retrospectively studied. The initial CF and LI at the start of the RF applications and mean CF and minimum LI during the RF applications were measured. The absolute and percentage LI drops were calculated as the difference between the initial and minimum LIs and 100 × absolute LI drop/initial LI, respectively.

Results

We analyzed 602 first‐pass RF applications. A weak correlation was observed between the initial CF and LI (r = 0.13) and between the mean CF and LI drops (r = 0.22). The initial LI and absolute and percentage LI drops were greater at effective ablation sites than ineffective ablation sites (median, 151 vs. 138 Ω, 22 vs. 14 Ω, and 14.4% vs. 9.9%; p < .001), but the initial and mean CF did not differ. At optimal cutoffs of 21 Ω and 10.8% for the absolute and percentage LI drops according to the receiver‐operating characteristic analysis, the sensitivity, and specificity for predicting an effective ablation were 57.4% and 88.9% and 80.0%, and 61.1%, respectively.

Conclusions

The effective sites during the CF‐guided CTI‐RFCA had greater initial LI and LI drops than the ineffective sites. Absolute and percentage LI drops of 21 Ω and 10.8% may be appropriate targets for an effective ablation.

Selection of an impedance- or magnetic field-based electro-anatomical mapping platform does not affect outcomes of outflow tract premature ventricular complex manual ablation

Comparative data are virtually missing about the performance of different electro-anatomical mapping (EAM) system platforms on outflow tract (OT) premature ventricular complex (PVC) ablation outcomes with manual ablation catheters. We aimed to compare the acute success-, complication-, and long-term recurrence rates of impedance-based (IMP) and magnetic field-based (MAG) EAM platforms in manual OT PVC ablation. Single-centre, propensity score matched data of 39-39 patients ablated for OT PVCs in 2015-17 with IMP or MAG platforms were analysed. Acute success rate, peri-procedural complications, post-ablation daily PVC burden, and long-term recurrence rates were compared on intention-to-treat basis. Acute success rate was similar in the IMP and MAG group (77 vs. 82%, p = 0.78). There was a single case of femoral pseudo-aneurysm and no cardiac tamponade occurred. PVC burden fell significantly from baseline 24.0% [15.0-30.0%] to 3.3% [0.25-10.5%] (p < 0.001) post-ablation, with no difference between EAM platforms (IMP: 2.6% [0.5-12.0%] vs. MAG: 4.0% [2.0-6.5%]; p = 0.60). There was no significant difference in recurrence-free survival of the intention-to-treat cohort of the IMP and MAG groups (54 vs. 60%, p = 0.82, respectively) during 12 months of follow-up. Ablation with the aid of both impedance- and magnetic field-based EAM platforms can considerably reduce OT PVC burden and give similar acute- and long-term freedom from arrhythmia.

Impact of open-irrigated radiofrequency catheter with contact force measurement on the efficacy and safety of atrial fibrillation ablation: a single-center direct comparison

BACKGROUND

In atrial fibrillation (AF) patients, catheter ablation of pulmonary veins (PVI) is the most effective therapeutic option to maintain sinus rhythm. To improve successful PVI, contact force-sensing (CF) catheters became routinely available. Previous studies did not clearly show superior clinical efficacy in comparison with non-CF catheters.

METHODS

We investigated consecutive patients, who underwent index PVI for AF at our hospital between 2012 and 2018. Three hundred and fifty-four patients were ablated without CF. After availability of CF catheters in 2016, 317 patients were ablated using CF. In case of crossover between the groups, follow-up was censored. The primary endpoint was any documented atrial tachycardia (AT) or atrial fibrillation > 30 s after a 3-month blanking period. Secondary endpoints were procedural characteristics and periprocedural complications.

RESULTS

There was no significant difference between the groups at baseline except hyperlipidemia. After 365 days of follow-up, 67% of patients in the CF group remained free from AF/AT recurrence compared to 59% in non-CF group (P = 0.038). In multivariable Cox regression analysis, non-CF ablation was an independent risk factor for AF recurrence besides age and persistent AF. Total fluoroscopy time (15 ± 7.6 vs. 28 ± 15.9 min) and total procedure time (114 ± 29.6 vs. 136 ± 38.5 min) were significantly lower for CF-guided PVI (P < 0.001). Complication rates did not differ between groups (P = 0.661).

CONCLUSIONS

In our study, the AT/AF recurrence rate and pulmonary vein reconnection rate is lower after CF PVI with a similar complication rate but lower total procedure time and total fluoroscopy time compared to non-CF PVI.

Cost-effectiveness of catheter ablation versus medical therapy for the treatment of atrial fibrillation in the United Kingdom

Introduction

Research evidence has shown that catheter ablation is a safe and superior treatment for atrial fibrillation (AF) compared to medical therapy, but real‐world practice has been slow to adopt an early interventional approach. This study aims to determine the cost effectiveness of catheter ablation compared to medical therapy from the perspective of the United Kingdom.

Methods

A patient‐level Markov health‐state transition model was used to conduct a cost‐utility analysis. The population included patients previously treated for AF with medical therapy, including those with heart failure (HF), simulated over a lifetime horizon. Data sources included published literature on utilization and cardiovascular event rates in real world patients, a systematic literature review and meta‐analysis of randomized controlled trials for AF recurrence, and publicly available government data/reports on costs.

Results

Catheter ablation resulted in a favorable incremental cost‐effectiveness ratio (ICER) of £8614 per additional quality adjusted life years (QALY) gained when compared to medical therapy. More patients in the medical therapy group failed rhythm control at any point compared to catheter ablation (72% vs. 24%) and at a faster rate (median time to treatment failure: 3.8 vs. 10 years). Additionally, catheter ablation was estimated to be more cost‐effective in patients with AF and HF (ICER = £6438) and remained cost‐effective over all tested time horizons (10, 15, and 20 years), with the ICER ranging from £9047–£15 737 per QALY gained.

Conclusion

Catheter ablation is a cost‐effective treatment for atrial fibrillation, compared to medical therapy, from the perspective of the UK National Health Service.

Radiofrequency ablation: technological trends, challenges, and opportunities

More than three decades have passed since utilization of radiofrequency (RF) ablation in the treatment of cardiac arrhythmias. Although several limitations and challenges still exist, with improvements in catheter designs and delivery of energy the way we do RF ablation now is much safer and more efficient. This review article aims to give an overview on historical advances on RF ablation and challenges in performing safe and efficient ablation.

Similar outcomes with manual contact force ablation catheters and traditional catheters in the treatment of outflow tract premature ventricular complexes

Aims

Unlike in atrial fibrillation ablation, there is a lack of appropriately sized and properly designed studies regarding outflow tract (OT) premature ventricular complex (PVC) ablation outcomes with contact force sensing (CFS) catheters. We aimed to compare the acute success-, complication-, and long-term recurrence rates of manual CFS catheters with traditional irrigated catheters (T) in OT PVC ablation.

Methods and results

Single-centre, propensity-matched data of 75–75 patients ablated for right-sided OT (RVOT) or left-sided OT (LVOT) PVCs in 2015–17 with CFS or T catheters were compared. Acute success rate, peri-procedural complications, post-procedural daily PVC burden, and long-term recurrence rates were compared on intention-to-treat basis. Acute success rate equalled 80% in both groups, with no difference in force values in the CFS group comparing successful or failed cases [12.0 (8.75–17.0) vs. 16.0 (10.25–22.25) g, P = 0.21]. There were three cases of pseudo-aneurysm and one cardiac tamponade. PVC burden fell significantly from baseline 22 (15–30)% to 2 (0–10)% (P < 0.0001), with no difference between catheter types [CFS: 1 (0–7)% vs. T: 4 (1–12) %; P = 0.21]. There was no significant difference in recurrence-free survival of CFS and T catheters (58 vs. 59%, P = 0.29) during 12 months of follow-up, respectively. Recurrence in the CFS group did not differ either by the force exerted below or above the median value of 12 g (P = 0.66).

Conclusion

Both types of catheters can effectively reduce OT PVC burden with minimal serious complication rates. Ablation with CFS or T catheters gives similar acute- and long-term results.

Impact of contact force sensing technology on outcome of catheter ablation of idiopathic pre-mature ventricular contractions originating from the outflow tracts

AIMS

Catheter ablation of frequent idiopathic pre-mature ventricular contractions (PVC) is increasingly performed. While potential benefits of contact force (CF)-sensing technology for atrial fibrillation ablation have been assessed in several studies, the impact of CF-sensing on ventricular arrhythmia ablation remains unknown. This study aimed to compare outcomes of idiopathic outflow tract PVC ablation when using standard ablation catheters as opposed to CF-sensing catheters.

METHODS AND RESULTS

In a retrospective multi-centre study, unselected patients undergoing catheter ablation of idiopathic outflow tract PVCs between 2013 and 2016 were enrolled. All procedures were performed using irrigated-tip ablation catheters and a 3D electro-anatomical mapping system. Sustained ablation success was defined as a  ≥80% reduction of pre-procedural PVC burden determined by 24 h Holter ECG during follow-up. Overall, 218 patients were enrolled (median age 52 years, 51% males). Baseline and procedural data were similar in the standard ablation (24%) and the CF-sensing group (76%). Overall, the median PVC burden decreased from 21% (IQR 10-30%) before ablation to 0.2% (IQR 0-3.0%) after a median follow-up of 2.3 months (IQR 1.4-3.9 months). The rates of both acute (91% vs. 91%, P = 0.94) and sustained success (79% vs. 74%, P = 0.44) were similar in the standard ablation and the CF-sensing groups. No differences were observed in subgroups according to arrhythmia origin from the RVOT (65%) or LVOT (35%). Complications were rare (1.8%) and evenly distributed between the two groups.

CONCLUSION

The use of CF-sensing technology is not associated with increased success rate nor decreased complication rate in idiopathic outflow tract PVC ablation.

Advances in Atrial Fibrillation Ablation: Energy Sources Here to Stay

Energy sources used for catheter ablation of atrial fibrillation (AF) ablation have undergone an exceptional journey over the past 50 years. Traditional energy sources, such as radiofrequency and cryoablation, have been the mainstay of AF ablation. Novel investigations have led to inclusion of other techniques, such as laser, high-frequency ultrasound, and microwave energy, in the armamentarium of electrophysiologists. Despite these modalities, AF has remained one of the most challenging arrhythmias. Advances in the understanding of electroporation promise to overcome the shortcomings of conventional energy sources. A thorough understanding of the biophysics and practical implications of the existing energy sources is paramount.

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.

Contact force ablation of accessory pathways in pediatric patients

INTRODUCTION

Contact force (CF) catheters provide feedback confirming adequate tissue contact for optimal lesion size and minimal complications. CF ablation catheters have resulted in decreased procedure times and improved outcomes for ablation of atrial fibrillation in adults. There is limited data evaluating CF use for accessory pathway (AP) ablation or in pediatric patients. The aim of our study was to compare a cohort who underwent AP ablation with a CF catheter to historical controls, evaluating for differences in procedure times, number of lesions, and outcomes.

METHODS

A retrospective chart review of CF ablation cases at Children's Wisconsin performed between June 2015 to April 2018 was compared to a historical control cohort of traditional radiofrequency (RF) ablations between June 2012 and June 2015. 43 patients with APs underwent 49 CF ablation procedures (18 males, 13.6 ± 3 years old) and a control cohort consisted of 77 procedures in 69 patients (38 males, 12.4 ± 4 years).

RESULTS

The groups did not differ significantly on procedure time (CF 2.01 ± 0.48 h, control 1.53 ± 0.48 h, p = .37), or total lesions administered (CF and control 7 ± 6 lesions, p = .89). CF cases showed a trend toward improvement in acute success (98% CF, 90% controls, p = .15) though with increased recurrence compared to controls (13% CF, 4.3% controls, p = .16), neither being statistically significant.

CONCLUSION

Our study suggests that ablation outcomes using CF are comparable to traditional RF ablation in pediatric patients with APs.

Complications in pulmonary vein isolation in the Netherlands Heart Registration differ with sex and ablation technique

Aims 

Pulmonary vein isolation (PVI) has become a cornerstone of the invasive treatment of atrial fibrillation. Severe complications are reported in 1–3% of patients. This study aims to compare complications and follow-up outcome of PVI in patients with atrial fibrillation.

Methods and results 

The data were extracted from the Netherlands Heart Registration. Procedural and follow-up outcomes in patients treated with conventional radiofrequency (C-RF), multielectrode phased RF (Ph-RF), or cryoballoon (CB) ablation from 2012 to 2017 were compared. Subgroup analysis was performed to identify variables associated with complications and repeat ablations. In total, 13 823 patients (69% male) were included. The reported complication incidence was 3.6%. Patients treated with C-RF developed more cardiac tamponades (C-RF 0.8% vs. Ph-RF 0.3% vs. CB 0.3%, P ≤ 0.001) and vascular complications (C-RF 1.7% vs. Ph-RF 1.2% vs. CB 1.3%, P ≤ 0.001). Ph-RF was associated with fewer bleeding complications (C-RF: 1.0% vs. Ph-RF: 0.4% vs. CB: 0.7%, P = 0.020). Phrenic nerve palsy mainly occurred in patients treated with CB (C-RF: 0.1% vs. Ph-RF: 0.2% vs. CB: 1.5%, P ≤ 0.001). In total, 18.4% of patients were referred for repeat ablation within 1 year. Female sex, age, and CHA2DS2-VASc were independent risk factors for cardiac tamponade and bleeding complications, with an adjusted OR for female patients of 2.97 (95% CI 1.98–4.45) and 2.02 (95% CI 1.03–4.00) respectively.

Conclusion 

The reported complication rate during PVI was low. Patients treated with C-RF ablation were more likely to develop cardiac tamponades and vascular complications. Female sex was associated with more cardiac tamponade and bleeding complications.

Optimal local impedance drops for an effective radiofrequency ablation during cavo-tricuspid isthmus ablation

PURPOSE

A novel ablation catheter capable of local impedance (LI) monitoring (IntellaNav MiFi OI, Boston Scientific) has been recently introduced to clinical practice. We aimed to determine the optimal LI drops for an effective radiofrequency ablation during cavo-tricuspid isthmus (CTI) ablation.

METHODS

This retrospective observational study enrolled 50 consecutive patients (68 ± 9 years; 34 males) who underwent a CTI ablation using the IntellaNav MiFi OI catheter, guided by Rhythmia. The LI at the start of radiofrequency applications (initial LI) and minimum LI during radiofrequency applications were evaluated. The absolute and percentage LI drops were defined as the difference between the initial and minimum LIs and 100× absolute LI drop/initial LI, respectively.

RESULTS

A total of 518 radiofrequency applications were analyzed. The absolute and percentage LI drops were significantly greater at effective ablation sites than ineffective sites (median, 15 ohms vs 8 ohms, P < .0001; median, 14.7% vs 8.3%, P < .0001). A receiver-operating characteristic analysis demonstrated that at optimal cutoffs of 12 ohms and 11.6% for the absolute and percentage LI drops, the sensitivity and specificity for predicting the effectiveness of the ablation were 66.5% and 88.2%, and 65.1% and 88.2%, respectively. Finally, bidirectional conduction block along the CTI was achieved in all patients.

CONCLUSIONS

During the LI-guided CTI ablation, the effective RF ablation sites exhibited significantly greater absolute and percentage LI drops than the ineffective RF ablation sites. Absolute and percentage LI drops of 12 ohms and 11.6% may be suitable targets for effective ablation.

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.

Impedance, power, and current in radiofrequency ablation: Insights from technical, ex vivo, and clinical studies

BACKGROUND

Radiofrequency (RF) power is routinely considered during RF application. In contrast, impedance has been relatively poorly studied, despite also influencing RF lesion creation. The aim of this study was to examine the influence of electric impedance on RF lesion characteristics and on clinical RF ablation parameters.

METHODS AND RESULTS

In the first part of the study, power and impedance were systematically varied and the resulting current was calculated using custom-made software. In the second part of the study, ablation lesions (n = 40) were analyzed in a porcine ex vivo model. RF applications were delivered in cardiac muscle preparations with systematically varied values of electric impedance using a contact force ablation catheter. In the third part of the study, n = 3378 clinical RF applications were analyzed, power, impedance, and current data were exported and correlated with clinical patient data. 20 ± 3 W/80 Ω, 30 ± 3 W/120 Ω, 40 ± 3 W/160 Ω, and 50 ± 3 W/200 Ω RF applications resulted in 498 ± 40, 499 ± 26, 500 ± 20, and 500 ± 16 mA RF current, which were not significantly different (p = .32). Ablation lesions were significantly different in depth and diameter when applied with the same power but different impedances (p < .01); lesion sizes decreased when increasing impedance. In clinical data, a large range of delivered current (e.g., 39-40 W: 530-754 mA) was measured, due to variations in impedance.

CONCLUSIONS

RF lesion creation is determined by current rather than by power. During clinical RF ablation procedures, impedance significantly influences current delivery and varies considerably between patients. Impedance and current are clinically relevant parameters that should be considered during RF ablation.

Electrical Impedance Tomography for monitoring cardiac radiofrequency ablation: a scoping review of an emerging technology

Arrhythmias are common cardiac diseases which can be treated effectively by the cardiac radiofrequency ablation (CRFA). However, information regarding the lesion growth within the myocardium is critical to the procedure's safety and efficacy but still unavailable in the current catheterisation lab (CathLab). Over the last 20 years, many efforts have been made in order to track the lesion size during the procedure. Unfortunately, all the approaches have their own limitations preventing them from the clinical translation and hence making the lesion size monitoring during a CRFA still an open issue. Electrical Impedance Tomography (EIT) is an impedance imaging modality that might be able to image the thermal-related impedance changes from which the lesion size can be measured. With the availability of the patient's CT scans, for a detailed model, and the catheter-based electrodes for the internal electrodes, EIT accuracy and sensitivity to the ablated sites can be significantly improved and is worth being explored for this application. Though EIT is still new to CRFA with no in-vivo experiments being done according to our up-to-date searching, many related EIT studies and its extensive research in Hyperthermia and other ablations can reveal many hints for a possibility of the CRFA-EIT application. In this paper, we present a review on multiple aspects of EIT in CRFA. First, the expected CRFA-EIT signal range and frequency are discussed based on various measured impedance results obtained from lesions in the past. Second, the possible noise sources that can happen in a clinical CRFA procedure, along with their signal range and frequency compared to the CRFA-EIT signal, and, third, the available current solutions to separate such noises from the CRFA-EIT signal. Finally, we review the progress of EIT in thermal applications over the last two decades in order to identify the developments that EIT can take advantage of and the current drawbacks that need to be solved for a potential CRFA-EIT application.

Long-term safety and effectiveness of paroxysmal atrial fibrillation ablation using a porous tip contact force-sensing catheter from the SMART SF trial

Purpose

The prospective, multicenter SMART SF trial demonstrated the acute safety and effectiveness of the 56-hole porous tip irrigated contact force (CF) catheter for drug-refractory paroxysmal atrial fibrillation (PAF) ablation with a low primary adverse event rate (2.5%), leading to FDA approval of the catheter. Here, we are reporting the long-term effectiveness and safety results that have not yet been reported.

Methods

Ablations were performed using the 56-hole porous tip irrigated CF catheter guided by the 3D mapping system stability module. The primary effectiveness endpoint was freedom from atrial tachyarrhythmia (including atrial fibrillation, atrial tachycardia, and/or atrial flutter), based on electrocardiographic data at 12 months. Atrial tachyarrhythmia recurrence occurring 3 months post procedure, acute procedural failures such as lack of entrance block confirmation of all PVs, and undergoing repeat procedure for atrial fibrillation in the evaluation period (91 to 365 days post the initial ablation procedure) were considered to be effectiveness failures.

Results

Seventy-eight patients (age 64.8 ± 9.7 years; male 52.6%; Caucasian 96.2%) participated in the 12-month effectiveness evaluation. Mean follow-up time was 373.5 ± 45.4 days. The Kaplan-Meier estimate of freedom from 12-month atrial tachyarrhythmia was 74.9%. Two procedure-related pericardial effusion events were reported at 92 and 180 days post procedure. There were no pulmonary vein stenosis complications or deaths reported through the 12-month follow-up period.

Conclusions

The SMART SF 12-month follow-up evaluation corroborates the early safety and effectiveness success previously reported for PAF ablation with STSF.

Safety and efficacy of the ThermoCool SmartTouch SurroundFlow catheter for atrial fibrillation ablation: A meta-analysis

Background

The ThermoCool Smarttouch Surroundflow catheter (STSFc) is an advanced catheter, which integrating contact force sensing and surroundflow technology. However, comparative data between STSFc and contact force sensing catheter (Thermocool SmartTouch catheter [STc]) are limited.

Hypothesis

We thought that STSFc might bring more clinical benefits. The aim of this meta‐analysis was to compare the safety and efficiency between the STSFc and the STc for treatment of atrial fibrillation (AF).

Methods

The Medline, PubMed, Embase, and Cochrane Library databases were searched for studies comparing STSFc and STc.

Results

Four trials involving 727 patients were included in the study. Pool‐analyses demonstrated that, as compared STc ablation, STSFc ablation was more beneficial in terms of procedural times (standard mean difference [SMD]: −0.22; 95% confidence interval [CI], −0.37 to −0.07, P = .005) and irrigation fluid volume (SMD: −1.94; 95% CI, −2.65 to −1.22, P < .0001). There was no significant difference between STSFc and STc (risk ratio [RR]: 1.02; 95% CI: 0.86 to 1.21, P = .79) for free from AF. Evidence of complications were low and similar for both groups (RR: 0.83; 95% CI: 0.19‐3.55, P = .80). Additionally, patients administered STSFc ablation tended to have shorter fluoroscopic times (SMD: −0.20; 95% CI, −0.63‐0.23, P = .21).

Conclusions

STSFc ablation was associated with reducing procedural times and irrigation fluid volume. Further, STSFc ablation tended to shorten fluoroscopic times. Therefore, STSFc ablation would be a better choice for AF patients especially in patients with heart failure.

The industrialization of ablation: a highly standardized and reproducible workflow for radiofrequency ablation of atrial fibrillation

BACKGROUND OR PURPOSE

The purpose of this analysis was to report on efficacy of a standardized workflow for atrial fibrillation (AF) ablation using technology advances such as 3D imaging and contact force sensing in a real-world setting.

METHODS

Consecutive AF ablations from 2014 to 2015 at a high-volume site in Belgium were included. The workflow consisted of a pre-specified procedure sequence including 3D modeling followed by radiofrequency encircling of the pulmonary veins (25 W posterior wall, 35 W anterior wall) with a THERMOCOOL SMARTTOUCH® Catheter guided by CARTO VISITAG™ Module (2.5 mm/5 s stability, 50% > 7 g) and ablation index (targets: 550 anterior wall, 400 posterior wall). Efficiency endpoints were procedure time, fluoroscopy time, and radiation dose. The primary effectiveness endpoint was freedom from atrial arrhythmia recurrence.

RESULTS

A total of 605 paroxysmal AF (PAF) and 182 persistent AF (PsAF) patients were followed for 436 ± 199 days. Mean procedure times were short (PAF: 96.1 ± 26.2 min; PsAF: 109.2 ± 35.6 min) with most procedures (90.6% PAF; 81.3% PsAF) completed in ≤ 120 min. Minimal fluoroscopy was utilized (PAF: 6.1 ± 3.8 min, 5.9 ± 3.4 Gy*cm²; PsAF: 6.9 ± 4.7 min, 7.4 ± 4.9 Gy*cm²). Freedom from atrial arrhythmia recurrence was higher for PAF than PsAF patients (OR: 2.0, 95% CI: 1.4-2.9, p = 0.0003), but adjusted mean rates were high in both groups (81.0% vs. 67.9%). Rates were adjusted for prior ablation and age (at 65 years).

CONCLUSION

AF ablation using a standardized workflow resulted in low procedure times and variability, with minimal fluoroscopy exposure. Long-term freedom from atrial arrhythmia recurrence was high in both PAF and PsAF populations.

Role of Contact Force Sensing in Catheter Ablation of Cardiac Arrhythmias: Evolution or History Repeating Itself?

Adequate catheter-tissue contact facilitates efficient heat energy transfer to target tissue. Tissue contact is thus critical to achieving lesion transmurality and success of radiofrequency (RF) ablation procedures, a fact recognized more than 2 decades ago. The availability of real-time contact force (CF)-sensing catheters has reinvigorated the field of ablation biophysics and optimized lesion formation. The ability to measure and display CF came with the promise of dramatic improvement in safety and efficacy; however, CF quality was noted to have just as important an influence on lesion formation as absolute CF quantity. Multiple other factors have emerged as key elements influencing effective lesion formation, including catheter stability, lesion contiguity and continuity, lesion density, contact homogeneity across a line of ablation, spatiotemporal dynamics of contact governed by cardiac and respiratory motion, contact directionality, and anatomic wall thickness, in addition to traditional ablation indices of power and RF duration. There is greater appreciation of surrogate markers as a guide to lesion formation, such as impedance fall, loss of pace capture, and change in unipolar electrogram morphology. In contrast, other surrogates such as tactile feedback, catheter motion, and electrogram amplitude are notably poor predictors of actual contact and lesion formation. This review aims to contextualize the role of CF sensing in lesion formation with respect of the fundamental principles of biophysics of RF ablation and summarize the state-of-the-art evidence behind the role of CF in optimizing lesion formation.

Endo/epicardial ablation of ventricular arrhythmias with contact force-sensing catheters in arrhythmogenic right ventricular dysplasia/cardiomyopathy

Objective:

To control ventricular arrhythmia in arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C), ablation may be required both from the endocardial and epicardial side. In this study, we analyzed the results of contact force–sensing (CFS) catheters in the endo/epicardial ablation of ventricular arrhythmias in ARVD/C.

Methods:

We included 17 patients with ARVD/C, 5 of whom had premature ventricular contractions (PVC), and the rest of them were admitted with a ventricular tachycardia (VT) storm, between September 2014 and October 2016. We divided patients into two groups: the PVC and VT groups. Irrigated CFS catheters (Smart Touch, Biosense Webster, Inc.) were utilized in all procedures.

Results:

In the PVC group, the mean ratio of PVC during the 24-hour Holter monitoring was 31.8±7.6%. The mean contact force during mapping and ablation in the right ventricle was 13±1.2 and 12.8±1.9 grams, respectively. The mean follow-up duration was 15±3.1 months for the PVC group. The left ventricular ejection fraction improved in all patients (52.8±10%). All patients in the VT group underwent endo/epicardial ablation, except one. The mean contact force during the endocardium and epicardium mapping was 12.5±1.2 and 12.5±4.6 grams, respectively. The mean contact force during ablation for the endocardium and epicardium was 12.1±1.4 and 12.8±1.9 grams, respectively. All clinical and non-clinical VTs were ablated successfully, except in 2 patients who still had non-clinical VTs. The mean follow-up was 15.5±4.5 months. None of the VT patients experienced electrical storm or death. Two patients had single shock, and 1 patient had two shocks during the follow-up.

Conclusion:

Endo/epicardial ablation of ventricular arrhythmias with CFS catheters in ARVD/C seems to be promising.

Late Gadolinium Enhancement Magnetic Resonance Imaging Guided Treatment of Post–Atrial Fibrillation Ablation Recurrent Arrhythmia

Background:

Macroreentrant atrial tachycardia (AT) accounts for 40% to 60% of recurrent atrial arrhythmias after atrial fibrillation (AF) ablation. To describe late gadolinium enhancement magnetic resonance imaging (LGE-MRI)–detected scar-based dechanneling as new ablation strategy to treat ATs after AF ablation.

Methods:

Data from 102 patients who underwent initial AF ablation and repeat ablation for recurrent atrial arrhythmia within 1-year follow-up were analyzed. All patients underwent LGE-MRI before initial and repeat ablation. Depending on the recurrent rhythm, patients with AF and AT recurrence were assigned to group 1 or 2, respectively. Group 1 underwent fibrosis homogenization as second procedure. Group 2 underwent LGE-MRI–detected scar-based dechanneling. Both groups underwent reisolation of pulmonary veins if necessary.

Results:

Forty-six patients (45%) presented with AF, and 56 patients (55%) presented with AT recurrence during follow-up after initial ablation. In the first 25 patients from group 2, the AT was electroanatomically mapped, and a critical isthmus was defined. It was found that those isthmi were located in the regions with nontransmural scarring detected by LGE-MRI. In the last 31 patients from group 2, an empirical LGE-MRI–based dechanneling was performed solely based on the LGE-MRI results. During 1-year follow-up after second ablation, 67% patients in group 1 and 64% patients in group 2 were free from recurrence (log-rank, P =1.000). In group 2, 64% in the electroanatomically guided and 65% in the LGE-MRI dechanneling group were free from recurrence (log-rank, P =0.900).

Conclusions:

Anatomic targeting of LGE-MRI–detected gaps and superficial atrial scar is feasible and effective to treat recurrent arrhythmias post-AF ablation. Homogenization of existing scar is the appropriate treatment for recurrent AF, whereas dechanneling of existing isthmi seems the right approach for patients recurring with AT.

Improving procedural and one-year outcome after contact force-guided pulmonary vein isolation: the role of interlesion distance, ablation index, and contact force variability in the 'CLOSE'-protocol

Aims

We have recently shown that a contact force (CF)-guided ablation protocol respecting region-specific criteria of lesion contiguity and lesion depth ('CLOSE' protocol) is associated with high incidence of acute durable pulmonary vein (PV) isolation (PVI) and a high single-procedure arrhythmia-free survival at 1 year. In the present study, we compared efficiency, safety, and efficacy of 'CLOSE'-guided PVI to conventional CF-guided PVI (CONV-CF).

Methods and results

Fifty consecutive paroxysmal atrial fibrillation (AF) patients underwent PV encircling using a CF-sensing catheter targeting an interlesion distance (ILD) ≤6 mm and ablation index (AI) ≥400 and ≥550 at posterior and anterior wall ('CLOSE' group). Results were compared to the last 50 patients undergoing 'CONV-CF'. All patients underwent adenosine testing after PVI. Arrhythmia recurrence was defined as any atrial tachyarrhythmia (ATA) >30 s on Holter at 3, 6, and 12 months. Clinical characteristics did not differ. Contact force variability was comparable in between both groups (proportion of applications with intermittent contact 2% in 'CLOSE' vs. 1% in CONV-CF, P = 0.67). In the 'CLOSE' group, procedure time and radiofrequency (RF) time per circle were shorter (respectively 149 ± 33 min vs. 192 ± 42 min, P < 0.0001 and 18 ± 4 min vs 28 ± 7.5 min, P < 0.0001) and incidence of adenosine-proof isolation was higher (97% vs. 82%, P < 0.001). No complications were observed in the 'CLOSE' group, one tamponade in the 'CONV-CF' group. At 12 months, single-procedure freedom from ATA was 94% in 'CLOSE' vs. 80% in 'CONV-CF' group (P < 0.05). In both groups, the majority of reconnections at repeat were associated with either ILD > 6 mm and/or AI < 400/550 (100% vs. 83%, P = 0.99).

Conclusion

'CLOSE'-guided PVI improves procedural and 1 year outcome in CF-guided PVI while shortening procedure time. Improvement cannot be explained by differences in CF variability and is most likely due to the strict application of criteria for contiguity and ablation index. A randomized controlled trial is needed to exclude the possible contribution of a learning curve.

Atrial fibrillation ablation with a spring sensor-irrigated contact force-sensing catheter compared with other ablation catheters: systematic literature review and meta-analysis

OBJECTIVES

The objective of our review was to systematically assess available evidence on the effectiveness, safety and efficiency of a spring sensor-irrigated contact force (CF) catheter (THERMOCOOL SMARTTOUCH Catheter (ST)) for percutaneous ablation of paroxysmal or persistent atrial fibrillation (AF), compared with other ablation catheters, or with the ST with the operator blinded to CF data.

DESIGN

Systematic literature review and meta-analysis.

BACKGROUND

Emerging evidence suggests improved clinical outcomes of AF ablation using CF-sensing catheters; however, reviews to date have included data from multiple, distinct CF technologies.

METHODS

We conducted a systematic review and meta-analysis of published studies comparing the use of ST versus other ablation catheters for the treatment of AF. A comprehensive search of electronic and manual sources was conducted. The primary endpoint was freedom from recurrent atrial tachyarrhythmia (AT) at 12 months. Procedural and safety data were also analysed.

RESULTS

Thirty-four studies enrolling 5004 patients were eligible. The use of ST was associated with increased odds of freedom from AT at 12 months (71.0%vs60.8%; OR 1.454, 95% CI 1.12 to 1.88, p=0.004) over the comparator group, and the effect size was most evident in paroxysmal AF patients (75.6%vs64.7%; OR 1.560, 95% CI 1.09 to 2.24, p=0.015). Procedure and fluoroscopy times were shorter with ST (p=0.05 and p<0.01, respectively, vs comparator groups). The reduction in procedure time is estimated at 15.5 min (9.0%), and fluoroscopy time 4.8 min (18.7%). Complication rates, including cardiac tamponade, did not differ between groups.

CONCLUSIONS

Compared with the use of other catheters, AF ablation using the CF-sensing ST catheter for AF is associated with improved success rates, shorter procedure and fluoroscopy times and similar safety profile.

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.

Economic impact of atrial fibrillation ablation with radiofrequency contact force catheter versus cryoballoon catheter

AIM

To compare health utilization among atrial fibrillation (AF) patients undergoing ablation with a contact force-sensing (CF) catheter versus a cryoballoon (CB) catheter.

METHODS

AF patients who underwent ablation using the CF catheter (THERMOCOOL SMARTTOUCH^® catheter) or CB catheter (Arctic Front™/Arctic Front Advance™ catheter) were identified from the Premier Healthcare database. Propensity score analyses were used to evaluate cost, length of stay and readmissions.

RESULTS

The CF catheter (n = 1409) was associated with significantly lower total (∼7%) and supply (∼13%) costs and a significantly lower likelihood of 4-12 month all-cause and CV-related readmission compared with the CB catheter (n = 2306).

CONCLUSION

Differential health utilization outcomes are associated with the CF catheter versus the CB catheter in AF ablation.

Resource use and clinical outcomes in patients with atrial fibrillation with ablation versus antiarrhythmic drug treatment

BACKGROUND

The objective of our study was to compare resource use and clinical outcomes among atrial fibrillation (AF) patients who underwent catheter ablation versus antiarrhythmic drug (AAD) treatment.

METHODS

A retrospective cohort design using the Clinical Practice Research Data-Hospital Episode Statistics linkage data from England (2008-2013) was used. Patients undergoing catheter ablation treatment for AF were indexed to the date of first procedure. AAD patients with at least two different AAD drugs were indexed to the first fill of the second AAD. Patients were matched using 1:1 propensity matching. Primary endpoints including inpatient and outpatient visits were compared between ablation and AAD cohorts in the 4 months-1 year period after index. Secondary endpoints including heart failure, stroke, cardioversion, mortality, and a composite outcome were compared for the 4 months-3 years post-index period in the two groups. Cox-proportional hazards models were estimated for clinical outcomes comparison.

RESULTS

A total of 558 patients were matched in the two groups for resource utilization comparison. The average number of cardiovascular (CV)-related outpatient visits in the 4-12 months post-index period were significantly lower in the ablation group versus the AAD group (1.76 vs 3.57, p < .0001). There was no significant difference in all-cause and CV-related inpatient visits and all-cause outpatient visits among the two groups. For secondary endpoints comparison, 615 matched patients in each group emerged. Ablation patients had 38% lower risk of heart failure (hazard ratio [HR] 0.62, p = 0.0318), 50% lower risk of mortality (HR 0.50, p = 0.0082), and 43% lower risk of experiencing a composite outcome (HR 0.57, p = 0.0009) as compared to AAD treatment cohort.

CONCLUSION

AF ablation was associated with significantly lower CV-related outpatient visits, and lower risk of heart failure and mortality versus AAD therapy.

Comparison of the efficacy between impedance-guided and contact force-guided atrial fibrillation ablation using an automated annotation system

BACKGROUND

This study compared the efficacy of catheter ablation of atrial fibrillation (AF) between impedance (IMP)-guided and contact force (CF)-guided annotation using the automated annotation system (VisiTag™).

METHODS

Fifty patients undergoing pulmonary vein isolation (PVI) for AF were randomized to the IMP-guided or CF-guided groups. The annotation criteria for VisiTag™ were a 10 second minimum ablation time and 2 mm maximum catheter movement range. A minimum CF of 10 g was added to the criteria in the CF-guided group. In the IMP-guided group, a minimum IMP drop of over 5 Ω was added to the criteria.

RESULTS

The rates of successful PVI after an initial ablation line were higher in the CF-guided group (80% vs 48%, P = .018). Although average CF was similar between two groups, the average force-time integral (FTI) was significantly higher in the CF-guided group (298.3 ± 65. 2 g·s vs 255.1 ± 38.3 g·s, P = .007). The atrial arrhythmia-free survival at 1 year demonstrated no difference between the two groups (84.0% in the IMP-guided group vs 80.0% in the CF-guided group, P = .737). If the use of any antiarrhythmic drug beyond the blanking period was considered as a failure, the clinical success rate at 1 year was 52.0% for the CF-guided group vs 56.0% for the IMP-guided group (P = .813).

CONCLUSIONS

Atrial fibrillation ablation using an automated annotation system guided by CF improved the success rate of PVI after the initial circumferential ablation. An IMP-guided annotation combined with catheter stability criteria showed similar clinical outcomes as compared to the CF-guided annotation.

Use of the THERMOCOOL SMARTTOUCH catheter for ablation of atrial fibrillation: the relationship between hospital procedure volume, re-admissions, and economic outcomes

OBJECTIVE

The purpose of this study was to examine the relationship between hospital volume of prior THERMOCOOL SMARTTOUCH catheter use and health and economic outcomes among hospitalized patients with atrial fibrillation (AF) undergoing ablation using this device.

MATERIALS AND METHODS

Patients aged ≥18 years with a primary diagnosis of AF undergoing ablation treatment using the THERMOCOOL SMARTTOUCH catheter between January 2014 and June 2016 were identified from the Premier hospital database with the first date of such a procedure being defined as the index date. Hospital volume of prior THERMOCOOL SMARTTOUCH catheter use was determined during the 12-month pre-index period, and was classified into five groups: no volume (0), low volume (1-50), mid volume (51-100), high volume (101-150), and very high volume (≥151). Outcomes, including length of stay (LOS; for inpatient procedure only), hospital costs (total, hospital pharmacy, supply), and all-cause re-admission were evaluated. A generalized estimating equation (GEE) with exchangeable correlation structure was used to examine the impact of hospital volume on LOS, hospital costs, and re-admissions controlling for hospital clustering and other covariates.

RESULTS

The study population included 640 hospitalized AF patients. The adjusted mean LOS was significantly shorter in very high-volume hospitals than hospitals with no volume (mean LOS 2.30 vs 4.33 days; p = .0377). As volume increased, the mean adjusted supply cost tended to decrease, although these changes emerged as non-significant. The 12-month all-cause re-admission was significantly lower among patients undergoing ablation in low (Odds ratio [OR] = 0.27; confidence interval [CI] = 0.08-0.85) and mid (OR = 0.12; CI = 0.02-0.61) volume hospitals compared to hospitals with no volume.

LIMITATIONS

Study results may not be generalizable to all US hospitals.

CONCLUSIONS

Among AF patients undergoing ablation, increased hospital volume of prior THERMOCOOL SMARTTOUCH catheter use was associated with shorter LOS and a lower likelihood of all-cause re-admission.

Contact force facilitates the achievement of an unexcitable ablation line during pulmonary vein isolation

AIMS

Contact force (CF) catheters provide catheter-tissue contact information to improve outcome of pulmonary vein isolation (PVI) in paroxysmal atrial fibrillation (PAF). We evaluated different target-CF values for achievement of the additional endpoint of an unexcitable ablation line.

METHODS

A total of 106 patients undergoing PVI were randomized into three groups (G) (G1: target-CF 15 g, G2: target-CF 10 g, G3: CF concealed from operator). The PVI encircling line was divided into predefined sections. Excitable tissue along the PVI-line identified by high output pacing (10 V, 2 ms) was targeted for further ablation.

RESULTS

Mean average CF was 17.4 ± 4.7 g (G1) vs. 12.3 ± 6.0 g (G2) vs. 11.1 ± 6.5 g (G 3) (p < 0.001). Primary unexcitable ablation lines were found in 38.6, 19.4 and 5.7% (G1, G2, G3 respectively; G1 vs. G2 p < 0.05, G1 vs. G3 p < 0.001, G2 vs. G3 ns). Additional radiofrequency (RF)-energy to achieve unexcitability was lowest in G1 (3.6 ± 3.1 kJ vs. 8.6 ± 7.2 kJ (G2) and 10.4 ± 6.7 (G3), p ≤ 0.001, G2 vs. G3 ns) with accordingly lowest additional RF applications in G1 (3.0 ± 2.6 vs. 7.0 ± 5.4 in G2 and 8.4 ± 4.0 in G3; G1 vs. G2 and G3, p < 0.001, G 2 vs. G 3 ns). Sections along ablation lines with low initial CF were most likely to reveal excitability. Single procedure success was 81.9 vs. 73.5 vs. 71.4% (G 1, 2 and 3, p = 0.6) during 437 ± 254 day follow-up.

CONCLUSION

Higher tip-to-tissue CF during PVI facilitates the achievement of an unexcitable ablation line, requiring less additional RF-energy.

Three-year outcomes and reconnection patterns after initial contact force guided pulmonary vein isolation for paroxysmal atrial fibrillation

BACKGROUND AND OBJECTIVE

Contact force (CF) sensing is a novel technology used for catheter ablation of atrial fibrillation (AF). We compared the single procedure success of CF-guided pulmonary vein isolation (PVI) with that of non-CF guided PVI during a 3-year (1,095 days) follow up period and analyzed the pattern of pulmonary vein (PV) reconnection.

METHODS

A cohort of 167 subjects (68 CF vs. 99 non-CF) with paroxysmal AF were included in the study. Atrial arrhythmia (AA) recurrence was defined as documented AF, atrial flutter, or atrial tachycardia lasting >30 seconds and occurring after 90 days.

RESULTS

Subjects in the CF group showed a statistically nonsignificant improvement in AA free survival compared to those in the non-CF group (66.2% vs. 51.5%; P value: 0.06). A greater propensity for reconnection was noted around the right-sided PVs compared to left-sided PVs related in both catheter ablation groups. For example, in the CF group 36% of right-sided segments reconnected compared to 16% of left-sided segments (P value <0.01).

CONCLUSIONS

A greater propensity for reconnection was noted around the right sided PV segments in both the CF and non-CF groups. The explanation for this finding was related to greater catheter instability around the right sided veins. Further research is needed to explore the utility of a "real-time" composite indicator that includes RF energy, CF and catheter stability in predicting transmural lesion formation during catheter ablation.