Ablation index‐guided 50 W ablation for pulmonary vein isolation in patients with atrial fibrillation: Procedural data, lesion analysis, and initial results from the FAFA AI High Power Study

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.

The Cutting Edge of Atrial Fibrillation Ablation

This article describes the advances in catheter ablation for AF that have allowed the creation of more durable and efficient lesions. It describes advances in high-power, short-duration radiofrequency ablation, radiofrequency balloon devices, ultra-low cryoablation and irreversible electroporation. It also considers the way these devices may change the way catheter ablation is performed for AF.

Safety and Efficacy of High Power Shorter Duration Ablation Guided by Ablation Index or Lesion Size Index in Atrial Fibrillation Ablation: A Systematic Review and Meta-Analysis

Background

High power shorter duration (HPSD) ablation may lead to safe and rapid lesion formation. However, the optimal radio frequency power to achieve the desired ablation index (AI) or lesion size index (LSI) is insubstantial. This analysis aimed to appraise the clinical safety and efficacy of HPSD guided by AI or LSI (HPSD-AI or LSI) in patients with atrial fibrillation (AF).

Methods

The Medline, PubMed, Embase, Web of Science, and the Cochrane Library databases from inception to November 2020 were searched for studies comparing HPSD-AI or LSI and low power longer duration (LPLD) ablation.

Results

Seven trials with 1013 patients were included in the analysis. The analyses verified that HPSD-AI or LSI revealed benefits of first-pass pulmonary vein isolation (PVI) (RR: 1.28; 95% CI: 1.05–1.56, P = 0.01) and acute pulmonary vein reconnection (PVR) (RR: 0.65; 95% CI: 0.48–0.88, P = 0.005) compared with LPLD. HPSD-AI or LSI showed higher freedom from atrial tachyarrhythmia (AT) (RR = 1.32, 95% CI: 1.14–1.53, P = 0.0002) in the subgroup analysis of studies with PVI ± (with or without additional ablation beyond PVI). HPSD-AI or LSI could short procedural time (WMD: −22.81; 95% CI, −35.03 to −10.60, P = 0.0003), ablation time (WMD: −10.80; 95% CI: −13.14 to −8.46, P < .00001), and fluoroscopy time (WMD: −7.71; 95% CI: −13.71 to −1.71, P = 0.01). Major complications and esophageal lesion in HPSD-AI or LSI group were no more than LDLP group (RR: 0.58; 95% CI: 0.20–1.69, P = 0.32) and (RR: 0.84; 95% CI: 0.43–1.61, P = 0.59).

Conclusions

HPSD-AI or LSI was efficient for treating AF with shorting procedural, ablation, and fluoroscopy time, higher first-pass PVI, and reducing acute PVR and may increase freedom from AT for patients with additional ablation beyond PVI compared with LPLD. Moreover, complications and esophageal lesion were low and no different between two groups.

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.

Biosense Webster's QDOT Micro™ radiofrequency ablation catheter

The QDOT Micro™ catheter (Biosense Webster, Inc., CA, USA) is a new radiofrequency ablation catheter based on the SmartTouch SF™ (Biosense Webster, Inc.). It combines diffuse external irrigation with six thermocouples located within the outer metal shell and three additional microelectrodes in a 3.5 mm-tip contact force radiofrequency catheter. This article focuses on the different characteristics of the catheter, which incorporates the ability of high power delivery, irrigation flow control based on temperature sensing through the six thermocouples and the generation of microelectrograms. An outline of its performance in preclinical and clinical setting is presented, showing promising results, especially concerning procedural efficiency and short-term safety. Additional studies need to confirm long-term effectiveness, and durability studies should evaluate whether superiority on a lesion quality level can be achieved.

Superior vena cava isolation with 50 W high power, short duration ablation strategy

INTRODUCTION

The optimal ablation strategy is unknown regarding a superior vena cava isolation (SVCI). This study aimed to examine the feasibility and safety and to analyze the lesion characteristics of the SVCI using high-power, short-duration (HPSD) ablation.

METHODS AND RESULTS

A total of 100 patients underwent an index SVCI using HPSD (n = 50, HPSD group) or conventional lower-power and longer-duration (n = 50, LPLD group) ablation, using the Thermocool Smarttouch SF. In the HPSD group, ablation was performed with a power of 50 W for 7 s, and was limited to 4 s at the lateral segment close to the right phrenic nerve. The ablation setting used in the LPLD group was 20-25 W for 20-30 s and was limited to 10-20 W for 15-30 s at the lateral segment when diaphragmatic capture was seen. An electrical SVCI was achieved in all patients. The HPSD group required a significantly shorter procedure time (10.8 ± 3.2 vs. 14.8 ± 6.4 min; p < .01), shorter radiofrequency duration (49 ± 16 vs. 282 ± 124 s; p < .01), fewer lesions (8.3 ± 2.5 vs. 10.4 ± 4.4; p < .01), and lower ablation index (316 ± 38 vs. 356 ± 62; p < .001) than the LPLD group. The incidence of a postprocedural asymptomatic mild diaphragmatic elevation was comparable (2% in the HPSD group vs. 6% in the LPLD group; p = .61).

CONCLUSION

The 50-W HPSD ablation strategy allowed for a successful, fast, and safe SVCI with the fewer ablation lesions and the lower ablation index.

Approach to recurrence of atrial fibrillation after catheter ablation

Atrial fibrillation (AF) is the most commonly observed sustained rhythm disorder during adult ages. Since it has been shown that the ectopic beat initiating AF is usually caused by pulmonary veins, AF ablation has become the mainstay of therapy worldwide. Cryoballoon and radiofrequency ablation are the most commonly used methods in today's technologies. However, despite technological advances, the success of a single procedure in AF ablation is still limited and multiple procedures may be required for the majority of patients. In cases in which a redo ablation is required, pulmonary vein isolation is still the main target, but non-pulmonary vein targets should also be considered in AF episodes that continue despite multiple ablations. Many issues are still unclear as to which energy to choose in the first procedure, and what ablation strategy will be utilized when a redo ablation is required. The studies on this subject are very limited but, it still seems feasible and a rational approach to utilize a customized treatment strategy in each specific patient subgroup.

Ablation Index-guided high-power (50 W) short-duration for left atrial anterior and roofline ablation: Feasibility, procedural data, and lesion analysis (AI High-Power Linear Ablation)

OBJECTIVES

To evaluate the feasibility, procedural data, and lesion characteristics of the anterior line (AL) and roofline (RL) ablation by using ablation index (AI)-guided high power (50 W) among patients with recurrent atrial fibrillation (AF) or atrial tachycardia (AT) after pulmonary vein isolation (PVI).

METHODS

Data from 35 consecutive patients with macro-reentrant left atrial tachycardia or substrate at the left atrium anterior wall or roof after previous PVI were collected. Ablation power was set to 50 W, targeting AI 500 for AL and 400 for RL. The first-pass conduction block (FPB) was evaluated. The AL was arbitrarily divided into three (caudal, middle, and cranial) segments to analyze the location of conduction gaps in non-FPB patients.

RESULTS

A total of 32 AL and 17 RL were deployed and FPB was achieved in 24 (75%) and 14 (82%) of them, respectively. In the non-FPB group, the most frequent gap location along the AL was the middle third. The final block of AL was achieved in 97%, and the block of RL was achieved in 100%. The radiofrequency (RF) ablation time was short (2.9 ± 0.8 min for AL and 46.2 ± 15.6 s for RL). For AL, the female gender was significantly more frequent in FPB than in non-FPB patients (p = .028); patients with non-FPB were associated with significantly longer RF time as compared to patients with FPB (204 ± 47 s vs. 161 ± 41 s; p = .02). No procedural complications occurred.

CONCLUSION

AI-guided high-power (50 W) ablation appears to be a feasible, effective, and fast technique for AL and RL ablation.

Efficiency, Safety, and Efficacy of High-Power Short-Duration Radiofrequency Ablation in Patients with Atrial Fibrillation

Pulmonary vein isolation (PVI) is the cornerstone therapy of atrial fibrillation (AF). Radiofrequency catheter ablation (RFCA) is performed using a point-by-point method to achieve durable PVI. However, this procedure remains complex and time-consuming, and the long-term clinical outcomes are still not satisfactory. Recently, there has been increasing interest in the clinical application of high-power short-duration (HPSD) approaches in the field of RFCA. HPSD ablation, distinguishing it from the conventional ablation strategy, delivers RF energy at a high power and saves the dwell time at each site. It is unknown whether the HPSD approach can bring some gratifying changes in the field of RF energy ablation. A number of experimental studies and clinical studies have been conducted regarding this topic. The review aimed to summarize the research findings and evaluate the procedural efficiency, safety, and clinical outcomes of the HPSD approach based on the evidence available to date.

Catheter ablation of atrial fibrillation using ablation index-guided high-power technique: Frankfurt AI high-power 15-month follow-up

BACKGROUND

Radiofrequency (RF) high-power ablation appears to be a novel concept in treating atrial fibrillation (AF). The ablation-index (AI) has been linked with the durability of pulmonary vein isolation (PVI). To report the midterm clinical results of a new ablation strategy using AI-guided high-power (50 W) ablation (AI-HP).

METHODS AND RESULTS

Symptomatic AF patients were included and underwent wide-area circumferential PVI. Contact-force catheters were used, RF power was set to 50 W targeting AI values (550/400 for anterior/posterior) and interlesion distance 6 mm. Luminal esophageal temperature (LET) was monitored during the procedure; patients with LET ≥39°C underwent post-ablation esophageal-endoscopy. Seventy-two-hour-Holter ECGs were scheduled during follow-up. Procedural PVI was achieved in all (N = 122; mean age, 68.2 years; male, 71.3%) patients, rate of first-pass PVI was 96.7% per patient. Procedural mean RF time was 11.5 min, and mean RF time during posterior wall segment was 3.1 min. Per RF-lesion, the mean contact force, RF duration, AI, and impedance-drop at anterior/posterior wall were 26 ± 14 g/23 ± 12 g, 16.2 ± 7.5 s/8.8 ± 3.6 s, 552 ± 53/438 ± 47, and 13 ± 6 Ω/9 ± 5 Ω, respectively. Mean PVI procedural-time, 55.8 min; mean procedural fluoroscopic time, 5.6 min. Three (2.5%) patients had asymptomatic endoscopic small erosion/erythema esophageal lesions, no serious adverse events were observed. During a 15-month follow-up, overall single-procedure freedom from clinical recurrence of AF/atrial tachycardia (AT) off antiarrhythmic drug after blanking period was 85.2% (89.4% for paroxysmal AF, 80.4% for persistent AF).

CONCLUSION

The AI-HP (50 W) appears as an efficient ablation technique in treating AF and leads to a high single-procedure arrhythmia-free survival at 15 months.

Incidence of ablation-induced esophageal injury associated with high-power short duration temperature-controlled pulmonary vein isolation using a specialized open-irrigated ablation catheter: A retrospective single-center study

INTRODUCTION

To evaluate short-term efficacy and incidence of ablation-induced endoscopically detected esophageal injury in patients undergoing high-power, short-duration (HPSD) pulmonary vein isolation using a novel irrigated radiofrequency ablation catheter and ablation generator setup.

METHODS AND RESULTS

Atrial fibrillation (AF) patients, who underwent AF ablation using an irrigated radiofrequency ablation catheter specifically designed for a HPSD ablation approach (50 W, with a target Ablation Index of 350 at posterior wall), received postablation esophageal endoscopy after ablation. In total 45 consecutive patients (67 ± 10 years; 58% male; 42% paroxysmal AF) undergoing AF ablation using a specialized ablation catheter (QDOT) were included in the study. Thirty-one of 45 patients (69%) underwent a first-time pulmonary vein isolation (Group 1, 67 ± 11 years; 55% male; 48% paroxysmal AF). Fourteen patients (31%) underwent a redo AF procedure (Group 2, 66 ± 8 years; 64% male; 29% paroxysmal AF). Patients undergoing first-time pulmonary vein isolation were included in the final analysis. In these patients an endoscopically detected esophageal lesion (EDEL) was detected in 5 of 31 (16%) patients (erosion n = 2, ulcer n = 3). Mean contact force at posterior wall ablation sites was significantly lower in patients with postprocedural EDEL compared with patients without EDEL (11.9 ± 0.8 g vs. 15.6 ± 4.7 g).

CONCLUSION

PVI using a specialized high-power ablation catheter in conjunction with a HPSD ablation approach results in a 16% incidence of EDEL in first AF ablation candidates. Future studies evaluating high-power short duration ablation strategies should include esophageal endoscopy to estimate the risk of clinically relevant esophageal complications.

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.

Cryoballoon Versus Laserballoon: Insights From the First Prospective Randomized Balloon Trial in Catheter Ablation of Atrial Fibrillation

BACKGROUND

Pulmonary vein isolation (PVI) represents the cornerstone in atrial fibrillation ablation. Cryoballoon and laserballoon catheters have emerged as promising devices but lack randomized comparisons. Therefore, we sought to compare efficacy and safety comparing both balloons in patients with persistent and paroxysmal atrial fibrillation (AF).

METHODS

Symptomatic AF patients (n=200) were prospectively randomized (1:1) to receive either cryoballoon or laserballoon PVI (cryoballoon: n=100: 50 paroxysmal atrial fibrillation + 50 persistent AF versus laserballoon: n=100: 50 paroxysmal atrial fibrillation + 50 persistent AF). All antiarrhythmic drugs were stopped after ablation. Follow-up included 3-day Holter-ECG recordings and office visits at 3, 6, and 12 months. Primary efficacy end point was defined as freedom from atrial tachyarrhythmia between 90 and 365 days after a single ablation. Secondary end points included procedural parameters and periprocedural complications.

RESULTS

Patient baseline parameters were not different between both groups. In all (n=200) complete PVI was obtained and the entire follow-up accomplished. Balloon only PVI was obtained in 98% (cryoballoon) versus 95% (laserballoon) requiring focal touch-up in 2 and 5 patients, respectively. Procedure but not fluoroscopy time was significantly shorter in the cryoballoon group (50.9±21.0 versus 96.0±20.4 minutes; P<0.0001 and 7.4±4.4 versus 8.4±3.2 minutes, P=0.083). Overall, the primary end point of no atrial tachyarrhythmia recurrence was met in 79% (cryoballoon: 80.0% versus laserballoon: 78.0%, P=ns). No death, atrio-esophageal fistula, tamponade, or vascular laceration requiring surgery occurred. In the cryoballoon group, 8 transient but no persistent phrenic nerve palsy were noted compared with 2 persistent phrenic nerve palsy and one transient ischemic attack in the laserballoon group.

CONCLUSIONS

Both balloon technologies represent highly effective and safe tools for PVI resulting in similar favorable rhythm outcome after 12 months. Use of the cryoballoon is associated with significantly shorter procedure but not fluoroscopy time.

Esophageal Thermal Injury after Catheter Ablation for Atrial Fibrillation with High-Power (50 Watts) Radiofrequency Energy

Background and Objectives

Data regarding the safety of atrial fibrillation (AF) ablation using high-power (50 W) radiofrequency (RF) energy in Asian populations are limited. This study was conducted to evaluate the incidence and pattern of esophageal injury after high-power AF ablation in an Asian cohort.

Methods

We searched the prospective AF ablation registry to identify patients who underwent AF ablation with 50 W RF energy using the smart touch surround flow catheter (Biosense Webster, Diamond Bar, CA, USA). Visitag™ (Biosense Webster) was used for lesion annotation with predefined settings of catheter stability (3 mm for 5 seconds) and minimum contact force (50% of time >5 g). All patients underwent upper gastrointestinal endoscopy at 1 or 3 days after the ablation.

Results

A total of 159 patients (mean age: 63±9 years, male: 69%, paroxysmal AF: 45.3%, persistent AF: 27.7%, long-standing persistent AF: 27.0%) were analyzed. Initially, 26 patients underwent pulmonary vein isolation with 50 W for 5 seconds at each point. The remaining 133 patients underwent prolonged RF duration (anterior 10 seconds and posterior 6 seconds). The incidence rates of esophageal erythema/erosion and superficial ulceration were 1.3% for each type of the lesion. Food stasis, a suggestive finding of gastroparesis, was observed in 25 (15.7%) patients. There were no cases of cardiac tamponade, stroke, or death.

Conclusions

In Asian patients, AF ablations using 50 W resulted in very low rates of mild esophageal complications.

Prospective Randomized Evaluation of High Power During CLOSE-Guided Pulmonary Vein Isolation: The POWER-AF Study

BACKGROUND

CLOSE-guided atrial fibrillation (AF) ablation is based on contiguous (intertag distance ≤6 mm), optimized (Ablation Index >550 anteriorly and >400 posteriorly) point-by-point radiofrequency lesions. The optimal radiofrequency power remains unknown.

METHODS

The POWER-AF study is a prospective, randomized controlled monocentric study including patients with paroxysmal AF, planned for first CLOSE-guided pulmonary vein isolation using a contact force radiofrequency catheter (Thermocool SmartTouch, Biosense Webster, Inc, Irvine, CA). A total of 100 patients were randomized into 2 groups (1:1). The control group received AF ablation using the standard CLOSE protocol (35 W), whereas in the experimental group, pulmonary vein isolation was performed using high power (45 W). Endoscopic evaluation was performed in patients with intraesophageal temperature rise >38.5 °C.

RESULTS

The resulting sample size was 96 (48+48) patients. In the high power group, shorter procedure time (80 versus 102 minutes, P<0.001), shorter total radiofrequency application time (16 versus 26 minutes, P<0.001), and radiofrequency time per application (26 versus 37 s anteriorly, P<0.001 and 13 versus 17 s posteriorly, P<0.001) were observed. Endoscopic evaluation (performed in 19/48 versus 25/48 patients respectively, P=0.31) showed an ulcerative perforation in a high power group patient (treated by endoscopic stenting and normalization after ≈4 months) and a superficial ulcerative lesion in a control group patient (conservative treatment). Both occurred following excessive Ablation Index applications (up to 460 and 480, respectively) with excessive contact force (30 g on average, with peaks up to 50 g). Six-months AF recurrence was not significantly different (10% in high power versus 8% in control, P=0.74).

CONCLUSIONS

This randomized controlled study shows that a 45 W radiofrequency power CLOSE protocol in patients with paroxysmal AF significantly increases the global procedural efficiency with similar midterm efficacy. However, our study showed a narrower safety margin and a limited increased efficiency at the posterior wall using high power. This advocates against the use of high power in the region neighboring the esophagus.

Improved Procedural Efficiency of Atrial Fibrillation Ablation Using a Dedicated Ablation Protocol and Lean Management

OBJECTIVES

In this study the authors hypothesized that "Lean management" within a dedicated ablation protocol could standardize the pulmonary vein isolation (PVI) procedure and improve quality.

BACKGROUND

There is a large variability in safety, effectiveness, and efficiency of PVI.

METHODS

This was a single-center prospective study with inclusion of all consecutive PVI procedures from 2017 to 2019. A 3-step intervention was introduced based on Lean management: step 1) simplification (CLOSE protocol); step 2) waste elimination (higher power shorter duration); and step 3) improved standardization (Lab Optimization Tool [LOT]). PVI was divided into steps that were tracked (in minutes) using LOT. Parameters were compared in 6-month intervals.

RESULTS

Overall, 295 patients (146 patients with LOT) were analyzed. Step 1 reduced skin-to-skin procedure duration (2017: 119 ± 21 min vs. 2018: 77 ± 15 min; p < 0.001) and variance (from 2018 to 2019 p = 0.024). Step 2 reduced the radiofrequency time (2017: 38 ± 6 min vs. 2018: 20 ± 3 min; p < 0.001) and variance (from 2018 to 2019 p < 0.001). Analysis of step 3 demonstrated that only 53% of the entire procedure length (143 ± 22 min) was used for treatment (skin-to-skin time 77 ± 16 min), the remaining time being devoted for setup (42 ± 12 min, 29%); left atrial access (16 ± 7 min, 12%); respiratory gating, left atrial map, and pseudo-circle annotation (10 ± 6 min, 7%); ablation (39 ± 10 min, 27%); and bilateral block validation (10 ± 8 min, 7%).

CONCLUSIONS

Standardization of PVI using a dedicated ablation protocol and Lean management can help to reduce procedure and radiofrequency ablation duration and variance, and increase procedural efficiency without compromising safety. To improve health care utilization, increased efficiency should become an accepted goal in addition to procedural safety and effectiveness.

Fluoroless and contrast-free catheter ablation without a lead apron in routine clinical practice

The technique of catheter ablation has been improved within the past few decades, especially by three-dimensional (3D) mapping system. 3D mapping system has reduced radiation exposure but ablation procedures still require fluoroscopy. Our previous study showed the safety and efficacy of catheter ablation based on intracardiac echogram combined with CARTOSOUND/CARTO3 system, however fluoroscopy use for an average of 16 min is required for this procedure. The present study was aimed to reduce radiation exposure to zero and establish a radiation free catheter ablation method with the goal of utilizing it in routine clinical practice. We conducted single center, retrospective study during 2019 April to 2020 February. Consecutive 76 patients were enrolled. In the first 18 cases, the previously reported procedure (CARTOSOUND/CARTO3 method) was used. The remaining 58 cases were transitioned to fluoroless catheter ablation. The procedure time, success rates and complication rates were analyzed. Not only AF patients but atrial flutter (AFL), paroxysmal supraventricular tachycardia (PSVT) and ventricular arrhythmia patients were included. Catheter positioning, catheter visualization and collecting the geometry of each camber of the heart were conducted by using contact force and ICE based geometry on CARTO system without either prior computed tomography (CT) or magnetic resonance image (MRI). In fluoroless group, all catheter ablations were successfully performed without lead aprons. No complications occurred in either group. There were no significant differences in procedure time in any type of procedure (Total procedure time Fluoro-group; 149 ± 51 min vs. Fluoroless-group; 162 ± 43 min, N.S.), (PSVT 170 ± 53 min vs. 162 ± 29 min, N.S.), (AFL 110 ± 70 min vs. 123 ± 43 min, N.S.), (AF 162 ± 43 min vs. 163 ± 32 min, N.S.). The total radiation time was reduced to zero in fluoroless group. Catheter ablation with ICE and 3D mapping system guide without fluoroscopy could be safely performed with a high success rate, without any prior CT/MRI 3D images. Radiation was reduced completely for patients and staff, negating the need for protective wear for operators.

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%.

Systematic review and network meta-analysis of atrial fibrillation percutaneous catheter ablation technologies using randomized controlled trials

AIMS

We sought out to make comparisons between all atrial fibrillation (AF) catheter ablation technologies using randomized controlled trial data. Our comparisons were freedom from AF, procedural duration, and fluoroscopy duration.

METHODS

Searches were made of EMBASE, MEDLINE, and CENTRAL databases, and studies were selected which had cryoballoon, conventional radiofrequency (RF), multipolar RF catheters, and laser technology as an arm in the study and were identified as randomized controlled trials (RCTs). These studies were analyzed for direct comparisons using conventional meta-analysis and a combination of indirect and direct comparisons via a network meta-analysis (NMA).

RESULTS

With respect to freedom from AF both direct comparisons and NMA did not demonstrate any significant difference. However in analysis of procedural and fluoroscopy duration (minutes) for the pulmonary vein ablation catheter (PVAC), both conventional analysis and NMA revealed significantly shorter procedure times, RF vs PVAC (conventional: 61.99 [38.03-85.94], P <.00001; NMA: 54.76 [36.64-72.88], P < .0001) and fluoroscopy times, RF vs PVAC (conventional: 12.96 [6.40-19.53], P = .0001; NMA: 8.89 [3.27-14.51], P < .01). The procedural duration was also shorter for the cryoballoon with NMA, RF vs CRYO (20.56 [3.47-37.65], P = .02).

DISCUSSION

Our analysis demonstrated that while there was no difference in the efficacy of the individual catheter technologies, there are significant differences in the procedural duration for the PVAC and the cryoballoon. While they may seem an attractive solution for high-volume centers, further RCTs of next-generation technologies should be examined.

Rationale and study design for ablation of paroxysmal atrial fibrillation guided by ablation index: a multi-center, prospective randomized trial (PAF-AI trial)

BACKGROUND

Pulmonary vein isolation (PVI) has become the cornerstone of atrial fibrillation (AF) ablation, but long-term success rates remains suboptimal, due in large part to late PV reconnection and insufficient ostial substrate modification.

OBJECTIVE

To evaluate whether ablation index (AI)-guided PVI with electrical isolation and quantified ostial substrate modification improves clinical outcomes when compared with contact force (CF)-guided ablation in patients with paroxysmal atrial fibrillation (PAF).

METHODS

The PAF-AI trial (ChiCTR1900022041) is a prospective, multi-center, randomized controlled clinical trial enrolling patients with PAF with an indication for catheter ablation. Patients are randomized into a 2:1 fashion to two treatment arms: AI-guided PVI (n = 151) and CF-guided PVI (n = 75). In the AI-guided PVI group, real-time automated display of radiofrequency applications (Visitag™) is used with AI ≥ 500 recommended at the anterior/superior/inferior walls and 350-400 at the posterior wall. In CF-guided PVI group, the value and direction of CF are displayed, with the lesion dots manually annotated. The primary endpoint is the freedom from AF recurrence at 12 months following ablation, without antiarrhythmic drug. The primary pre-specified secondary endpoints include intraprocedural efficiency and peri-procedural complications.

CONCLUSIONS

PAF-AI trial compares the effectiveness and safety of two different strategies of PVI in patients with PAF, AI-guided PVI versus more established CF-guided PVI. This prospective, multi-center, randomized controlled trial, with comparative data evaluating procedural and long-term follow-up results, aims to evaluate the impact of AI-guided strategy on AF ablation compared with the current standard of care RF ablation approach.

The low acute effectiveness of a high-power short duration radiofrequency current application technique in pulmonary vein isolation for atrial fibrillation

BACKGROUND

Application of high power radiofrequency (RF) energy for a short duration (HPSD) to isolate pulmonary vein (PV) is an emerging technique. But power and duration settings are very different across different centers. Moreover, despite encouraging preclinical and clinical data, studies measuring acute effectiveness of various HPSD settings are limited.

METHODS

Twenty-five consecutive patients with symptomatic atrial fibrillation (AF) were treated with pulmonary vein isolation (PVI) using HPSD. PVI was performed with a contact force catheter (Thermocool SF Smart-Touch) and Carto 3 System. The following parameters were used: energy output 50 W, target temperature 43°C, irrigation 15 mL/min, targeted contact force of > 10 g. RF energy was applied for 6-10 s. Required minimal interlesion distance was 4 mm. Twenty minutes after each successful PVI adenosine provocation test (APT) was performed by administrating 18 mg adenosine to unmask dormant PV conduction.

RESULTS

All PVs (100 PVs) were successfully isolated. RF lesions needed per patient were 131 ± 41, the average duration for each RF application was 8.1 ± 1.7 s. Procedure time was 138 ± 21 min and average of total RF energy duration was 16.3 ± 5.2 min and average amount of RF energy was 48209 ± 12808 W. APT application time after PVI was 31.1 ± 8.3 min for the left sided PVs and 22.2 ± 4.6 min (p = 0.005) for the right sided PVs. APT was transiently positive in 18 PVs (18%) in 8 (32%) patients.

CONCLUSIONS

Pulmonary vein isolation with high power for 6-10 s is feasible and shortens the procedure and ablation duration. However, acute effectiveness of the HPSD seems to be lower than expected. Further studies combining other ablation parameters are needed to improve this promising technique.