Five seconds of 50-60 W radio frequency atrial ablations were transmural and safe: an in vitro mechanistic assessment and force-controlled in vivo validation

Very high-power and short-duration radiofrequency ablation for atrial fibrillation in a Latin American low-volume private center

BACKGROUND

Center volume and operator experience/training are important factors impacting outcomes in AFib CA. Setting for RF delivery (power, duration, and contact force) associated with better outcomes remains to be determined.

METHODS

This is an observational, longitudinal, and retrospective study. All consecutive procedures performed between December 12, 2013, and March 9, 2023, in a low-volume private center in Latin America were analyzed. Procedure characteristics and outcomes were compared between STD and vHPSD.

RESULTS

Two hundred ten procedures were performed on 194 patients. Median annual number of procedures was 19 (7-29). Median age was 62 (52-68), and majority were male (71%). Median procedure duration was 155 (125-195) min, mean fluoroscopy time 32.8 ± 15 min and mean fluoroscopy dose 373.5 ± 208.9 mGray. Median follow-up was 27 months, significantly longer in STD compared with vHPSD group (43 [31-68] vs. 13 [8-19], respectively; P ≤ 0.001). The recurrence rate was 33.2% and major complications 8.6%. Compared with STD, vHPSD resulted in a significantly shorter procedure duration (125 vs. 180 min, P ≤ 0.001), shorter fluoroscopy time (22.7 ± 9.5 vs. 39.2 ± 14.3 min, P ≤ 0.001), and lower fluoroscopy dose (283.8 ± 161.1 vs. 438.3 ± 216.1 mGray, P ≤ 0.001). No long-term recurrence difference was observed when the follow-up periods were comparable. No difference in complication rate was observed (8.5% vs. 8.6%, P = 0.988).

CONCLUSIONS

Outcomes in AFib CA in a Latin American low-volume private center can be considered acceptable, with efficacy and safety similar to those reported in the literature. Compared with STD ablation, vHPSD showed higher efficiency with similar efficacy and safety.

High-power short-duration versus low-power long-duration ablation for pulmonary vein isolation: A substudy of the AWARE randomized controlled trial

INTRODUCTION

Pulmonary vein isolations (PVI) are being performed using a high-power, short-duration (HPSD) strategy. The purpose of this study was to compare the clinical efficacy and safety outcomes of an HPSD versus low-power, long-duration (LPLD) approach to PVI in patients with paroxysmal atrial fibrillation (AF).

METHODS

Patients were grouped according to a HPSD (≥40 W) or LPLD (≤35 W) strategy. The primary endpoint was the 1-year recurrence of any atrial arrhythmia lasting ≥30 s, detected using three 14-day ambulatory continuous ECG monitoring. Procedural and safety endpoints were also evaluated. The primary analysis were regression models incorporating propensity scores yielding adjusted relative risk (RRa ) and mean difference (MDa ) estimates.

RESULTS

Of the 398 patients included in the AWARE Trial, 173 (43%) underwent HPSD and 225 (57%) LPLD ablation. The distribution of power was 50 W in 75%, 45 W in 20%, and 40 W in 5% in the HPSD group, and 35 W with 25 W on the posterior wall in the LPLD group. The primary outcome was not statistically significant at 30.1% versus 22.2% in HPSD and LPLD groups with RRa 0.77 (95% confidence interval [CI]) 0.55-1.10; p = .165). The secondary outcome of repeat catheter ablation was not statistically significant at 6.9% and 9.8% (RRa 1.59 [95% CI 0.77-3.30]; p = .208) respectively, nor was the incidence of any ECG documented AF during the blanking period: 1.7% versus 8.0% (RRa 3.95 [95% CI 1.00-15.61; p = .049) in the HPSD versus LPLD group respectively. The total procedure time was significantly shorter in the HPSD group (MDa 97.5 min [95% CI 84.8-110.4)]; p < .0001) with no difference in adjudicated serious adverse events.

CONCLUSIONS

An HPSD strategy was associated with significantly shorter procedural times with similar efficacy in terms of clinical arrhythmia recurrence. Importantly, there was no signal for increased harm with a HPSD strategy.

Very-high-power Short-duration Ablation versus Conventional Ablation for Pulmonary Vein Isolation in Atrial Fibrillation: Systematic Review and Meta-analysis

The aim of this study was to compare the effectiveness and safety of very-high-power short-duration (VHPSD) ablation (70-90 W/4-7 s) with conventional ablation (30-40 W/>20 s, 50 W/7-11 s) for pulmonary vein isolation (PVI) in patients with AF. A total of 13 studies were included in this analysis (1,527 patients). AF recurrence occurred in 14% (95% CI [11-18%]) of the VHPSD group. VHPSD was associated with lower AF recurrence (OR 0.65; 95% CI [0.48-0.89]; p=0.006) compared with the conventional ablation group. Subgroup analysis showed that additional ablation beyond PVI had a similar rate of AF recurrence (16% versus 10%) compared with PVI alone. Procedure and ablation durations were significantly shorter in the VHPSD group with a mean differences of -14.4 minutes (p=0.017) and -14.1 minutes (p<0.001), respectively. Complications occurred in 6% (95% CI [3-9%]) of the VHPSD group, and the rate was similar between the two groups (OR 1.03; 95% CI [0.60-1.80]; p=0.498). VHPSD ablation resulted in less AF recurrence and a shorter procedure time. Additional ablation beyond PVI alone in VHPSD may not provide additional benefits.

Comparison of clinical outcomes of Ibutilide-guided cardioversion and direct current synchronized cardioversion after radiofrequency ablation of persistent atrial fibrillation

Backgroup

Ibutilide has already been used for cardioversion of persistent atrial fibrillation (PsAF) after radiofrequency catheter ablation (RFCA). The purpose of this study was to determine the effect of Ibutilide-guided cardioversion on clinical outcomes after individualized ablation of PsAF.

Methods

From October 2020 to September 2021, consecutive patients with PsAF accepted for RFCA were prospectively enrolled. After individualized ablation including pulmonary vein isolation plus left atrial roof line ablation and personalized linear ablation based on left atrial low-voltage zones, patients were divided into the spontaneous conversion (SCV) group, direct current synchronized cardioversion (DCC) group and Ibutilide group according to different cardioversion types during ablation. The rates of freedom from atrial tachyarrhythmia (ATT) among the three groups were evaluated after follow-up.

Results

In this study, 110 patients were enrolled, including 12 patients with SCV, 50 patients receiving DCC and 48 patients receiving Ibutilide cardioversion after individualized ablation. Among the three groups, the SCV group had shorter AF duration {12 months [interquartile range (IQR) 12-16], P = 0.042} and smaller left atrial diameter (LAD) [35 mm (IQR: 33-42), P = 0.023]. A 12-month freedom from ATT rate was 83.3% in SCV group, 69.4% in DCC group, and 79.2% in Ibutilide group, respectively (Log-rank, P = 0.745). During the follow-up [17 months (IQR: 15-19)], the rate of freedom from ATT of SCV group (83.3%), and Ibutilide group (72.9%) were both higher than that of DCC group (53.1%, P = 0.042). Moreover, Kaplan-Meier analysis showed a significantly higher sinus rhythm (SR) maintenance in Ibutilide group than in DCC group (Log-rank, P = 0.041). After adjusting for risk factors of AF recurrence, the hazard ratio for AF recurrence of the DCC group with reference to the Ibutilide group was 4.10 [95% confidence interval (CI) (1.87-8.98), P < 0.001]. Furthermore, subgroup analysis showed that freedom from ATT rate in effective Ibutilide subgroup was significantly higher than noneffective Ibutilide subgroup (Log-rank, P < 0.001).

Conclusion

For the treatment of the patients with PsAF, Ibutilide-guided cardioversion after individualized RFCA may be benefit for maintenance of SR compared to conventional DCC, especially for the patients who are effective for administration of Ibutilide.

Index-Guided High-Power Radiofrequency Catheter Ablation for Atrial Fibrillation: A Systematic Review and Meta-Analysis Study

PURPOSE OF REVIEW

Studies have suggested the superiority of high-power compared to standard-power radiofrequency ablation ablation (RFCA). This study aimed to assess the efficacy and safety of high-power compared to standard-power RFCA guided by ablation index (AI) or lesion index (LSI).

RECENT FINDINGS

A systematic review and meta-analysis study comparing IGHP and IGLP approaches for AF ablation was conducted. The relevant published studies comparing IGHP and IGSP methods for RFCA in AF patients until October 2022 were collected from Cochrane, ProQuest, PubMed, and ScienceDirect. A total of 2579 AF patients from 11 studies were included, 1682 received IGHP RFCA, and 897 received IGSP RFCA. To achieve successful pulmonary vein isolation (PVI), the IGHP RFCA group had a significantly shorter procedure time than the IGHP RFCA group (mean difference (MD) -19.91 min; 95% CI -25.23 to -14.59 min; p < 0.01), radiofrequency (RF) application time (MD -10.92 min; 95% CI -14.70 to -7.13 min; p < 0.01), and fewer number of lesions (MD -10.90; 95% CI -18.77 to -3.02; p < 0.01) than the IGSP RFCA. First-pass PVI was significantly greater in the IGHP RFCA group than in the IGSP RFCA group (risk ratio (RR) 1.17; 95% CI 1.07 to 1.28; p < 0.01). The IGHP RFCA is an effective and efficient strategy for AF ablation. The superiority of IGHP RFCA includes the shorter procedure time, shorter RF application time, fewer number of lesions for complete PVI, and more excellent first-pass PVI.

Comparison of effectiveness and safety of high-power vs. conventional-power radiofrequency ablation for treatment of atrial fibrillation

Aim

To compare high-power (HP) vs. conventional-power (CP) radiofrequency ablation for atrial fibrillation (AF).

Methods

We retrospectively enrolled AF patients undergoing CP (30-40 W, 43 patients) or HP (50 W, 49 patients) radiofrequency ablation. Immediate pulmonary vein (PV) single-circle isolation, PV-ablation time, AF recurrence, AF recurrence-free survival, and complications were analyzed.

Results

Diabetes was more common in the CP group than in the HP group (27.91% vs. 10.20%, P = 0.029). The left PV single-circle isolation rate (62.79% vs. 65.31%), right PV single-circle isolation rate (48.84% vs. 53.06%), and bilateral PV single-circle isolation rate (32.56% vs. 38.78%; all P > 0.05) did not differ between the groups. Single-circle ablation times for the left PVs (12.79 ± 3.39 vs. 22.94 ± 6.39 min), right PVs (12.18 ± 3.46 vs. 20.67 ± 5.44 min), and all PVs (25.85 ± 6.04 vs. 45.66 ± 11.11 min; all P < 0.001) were shorter in the HP group. Atrial fibrillation recurrence within 3 months (13.95% vs. 18.37%), at 3 months (11.63% vs. 8.16%), and at 6 months after ablation (18.60% vs. 12.24%; all P > 0.05) was similar in both groups. Atrial fibrillation recurrence-free survival did not differ between the groups (Kaplan-Meier analysis). Cardiac rupture and pericardial tamponade did not occur in any patient. Pops occurred in 2 and 0 patients in the HP and CP groups, respectively (4.08% vs. 0.00%, P = 0.533).

Conclusion

High-power ablation improved operation time and efficiency without increasing complications.

Ablation index-guided high-power ablation for superior vena cava isolation in patients with atrial fibrillation

Background

The strategy of ablation index (AI)-guided high-power ablation seems to be a novel strategy for performing pulmonary vein isolation (PVI). An AI-guided high-power ablation strategy was used in this study to determine whether superior vena cava isolation (SVCI) after PVI was feasible and safe for patients with AF.

Methods

Data from 53 patients with AF were collected. Mapping and ablation of SVC were performed. The applied power was set at 45 W and the procedure was guided by AI. The SVC was divided into six segments in a cranial view. The RF applications and AI values in different segments were compared and analyzed. Using receiver operating characteristic (ROC) analysis, the diagnostic accuracy of AI value for predicting segment block was evaluated.

Results

Electrical SVCIs were successfully achieved in all patients. SVCI was performed by segment ablation in most cases, with RF applications in different segments. The mean AI value in non-lateral walls was higher than that of the lateral wall (392 ± 28 vs. 371 ± 37, P < 0.001). Acutely blocked sites had significantly larger AI values compared with no-blocked sites (390 ± 30 vs. 343 ± 23, P < 0.001). The optimal AI cut-off value for non-lateral segments was 379 (sensitivity: 75.9%, specificity: 100%) and for lateral segments was 345 (sensitivity: 82.3%, specificity: 100%).

Conclusion

The AI values were predictive of the acute conduction block of SVCI. With AI values of 345 and 379, respectively, conduction block was achieved in the lateral walls at a lower level than in the non-lateral walls.

Massive pleural effusion following high-power and short-duration radiofrequency ablation for treatment of atrial fibrillation: A case report and review of the literature

Postpericardial injury syndrome (PPIS) is defined as pericarditis or pericardial effusion that results from recent myocardial infarction or intracardiac interventions. These symptoms typically include fever, leukocytosis, a high erythrocyte sedimentation rate, and elevated C-reactive protein levels. Additionally, pericardial effusion and pleural effusion may be present. It is considered to be a common complication in cardio-surgery with an occurrence of 3-30%. In the past 20 years, a high number of patients with atrial fibrillation have suffered from PPIS following radiofrequency catheter ablation. However, previous reports focused on identifying cardiac tamponade and pericardial effusion as their main clinical manifestations. Solitary pulmonary involvement following PPIS with the radiofrequency catheter ablation may occur. We report a case of PPIS that presented pleural effusion as the dominant feature soon after the operation and systematic review to illustrate the clinical characteristics of PPIS.

Effectiveness and Safety of High-Power Radiofrequency Ablation Guided by Ablation Index for the Treatment of Atrial Fibrillation

Background

To investigate the efficacy and safety of ablation index- (AI-) guided high-power radiofrequency ablation in the treatment of atrial fibrillation (AF).

Methods

Outcomes of radiofrequency (RF) applications were compared in a swine ventricular endocardial model (n = 10 each for 50 W, 40 W, and 30 W; AI = 500). And a total of 100 consecutive patients with paroxysmal AF undergoing pulmonary vein isolation (PVI) were included. The patients were divided into two groups (n = 50 for each) as follows: control group, treated with conventional power (30 W) ablation mode; and study group, treated with high power (40 W) radiofrequency ablation mode. All groups were treated with the same AI value guided the ablation (target AI = 400/500 on posterior/anterior wall, respectively). Acute pulmonary vein (PV) reconnection was assessed post adenosine administration 20 minutes after ablation. Subsequently, pathological observation of porcine heart lesions and necrotic tissue was performed. Additionally, statistical analyses were carried out on patients' baseline clinical characteristics, surgical data, and total RF energy.

Results

In swine ventricular endocardial RF applications, compared with 40 W and 30 W, the use of 50 W was associated with shallower tissue lesion depth (p < 0.001) and greater lesion maximum diameter (p < 0.001). Compared with 40 W and 30 W, tissue necrosis caused by 50 W was the deepest and largest (p < 0.001). In pulmonary vein isolation (PVI), there was no significant difference in baseline data between the study group and control group (p > 0.05). In patients with paroxysmal atrial fibrillation, the procedure time in the high-power group was significantly shortened (p < 0.001). The ablation time was significantly shorter (p < 0.001). Compared with control group, RF energy per point and acute pulmonary vein (PV) reconnection were lower (p < 0.001), and first-pass PVI was higher (p < 0.01) in study group. There were no significant differences in complications and sinus rhythm maintenance at 12 months between the two groups (p > 0.05).

Conclusions

Compared with conventional (30 W) PVI, AI-guided high-power (40 W) was safe and associated with shorter procedure time and reduced acute PV reconnection.

Procedural Efficiency, Efficacy, and Safety of High-Power, Short-Duration Radiofrequency Ablation Delivered by STSF Catheter for Paroxysmal Atrial Fibrillation

Objectives

To investigate the procedural efficiency, efficacy, and safety of high-power, short-term radiofrequency ablation delivered by the SmartTouch Surround Flow (STSF) catheter for paroxysmal atrial fibrillation (AF).

Methods

We retrospectively analyzed a total of 72 patients who were admitted with paroxysmal AF, and who underwent radiofrequency catheter ablation (RFCA) for the first time. Of these patients, 36 cases underwent low-power, long-duration (LPLD, (30–35 W/20–40 s) pulmonary vein isolation (PVI) delivered by an SmartTouch (ST) catheter (control group), and the other 36 cases underwent high-power, short-duration (HPSD, (45–50 W/10–20 s) PVI delivered by a STSF catheter (study group). The baseline data, duration of PVI, procedural time, fluoroscopy time, the rate of first-pass isolation, irrigation perfusion, eschar and steam pop occurrences, intraoperative complications, and the rate of stable sinus rhythm maintenance following a blanking period of three months were analyzed between the two groups.

Results

The isolation time of bilateral PVI and procedural time in the study group were markedly less than in controls (p < 0.01). The rate of first-pass isolation in the study group was significantly higher than in the control group (95.8% vs. 84.7%, p = 0.023), while the fluid perfusion in the study group was approximately 20% less than that in the control group (767 ± 171 vs. 966 ± 227 ml, p < 0.001). We observed no severe complications in any patients. The rate of freedom from AF recurrences following a blanking period of three months showed a tendency to be higher than in controls (93.9% vs. 87.1%, p = 0.348).

Conclusions

The HPSD strategy delivered by the STSF catheter was superior to conventional LPLD ablation through the ST catheter with respect to efficiency, acute procedural effectiveness, short-term safety, and the risk of heart failure in patients with paroxysmal AF.

Comparison between High-Power Short-Duration and Conventional Ablation Strategy in Atrial Fibrillation: An Updated Meta-Analysis

High-power short-duration (HPSD) setting during radiofrequency ablation has become an attempt to improve atrial fibrillation (AF) treatment outcomes. This study ought to compare the efficacy, safety, and effectiveness between HPSD and conventional settings. PubMed, Embase, and Cochrane Library were searched. Studies that compared HPSD and conventional radiofrequency ablation settings in AF patients were included while studies performed additional ablations on nonpulmonary vein targets without clear recording were excluded. Data were pooled with random-effect model. Efficacy endpoints include first-pass pulmonary vein isolation (PVI), acute pulmonary vein (PV) reconnection, free from AF, and free from atrial tachycardia (AT) during follow-up. Safety endpoints include esophagus injury rate and major complication rate. Effectiveness endpoints include complete PVI rate, total procedure time, PVI time, and PVI radiofrequency ablation (PVI RF) time. We included 22 studies with 3867 atrial fibrillation patients in total (2393 patients received HPSD radiofrequency ablation). Perioperatively, the HPSD group showed a higher first-pass PVI rate (risk ratio, $\text{RR}=1.10$ , $P=0.0001$ ) and less acute PV reconnection rate ( $\text{RR}=0.56$ , $P=0.0004$ ) than the conventional group. During follow-up, free from AF ( $\text{RR}=1.11$ , $P=0.16$ ) or AT ( $\text{RR}=1.06$ , $P=0.24$ ) rate did not differ between HPSD and conventional groups 6-month postsurgery. However, the HPSD group showed both higher free from AF ( $\text{RR}=1.17$ , $P=0.0003$ ) and AT ( $\text{RR}=1.11$ , $P<0.0001$ ) rate than the conventional group 12-month postsurgery. The esophagus injury ( $\text{RR}=0.99$ , $P=0.98$ ) and major complications ( $\text{RR}=0.76$ , $P=0.70$ ) rates did not differ between the two groups. The HPSD group took shorter total procedure time ( $\text{MD}=-33.71$ 95% CI: -43.10 to -24.33, $P<0.00001$ ), PVI time ( $\text{MD}=-21.60$ 95% CI: -25.00 to -18.21, $P<0.00001$ ), and PVI RF time ( $\text{MD}=-13.72$ , 95% CI: -14.45 to -13.00, $P<0.00001$ ) than conventional groups while complete procedure rate did not differ between two groups ( $\text{RR}=1.00$ , $P=0.93$ ). HPSD setting during AF radiofrequency ablation has better effectiveness, efficacy, and similar safety compared with the conventional setting.

Esophageal temperature during atrial fibrillation ablation poorly predicts esophageal injury: An observational study

Background

Esophageal injury (EI) remains a concern when performing pulmonary vein isolation (PVI) using the high-power short-duration (HPSD) technique.

Objective

We aim to indicate that high esophageal temperature during HPSD PVI does not correlate with positive esophageal endoscopy (EGD) findings.

Methods

A retrospective observational study was performed on 43 patients undergoing PVI using HPSD (50 W for 6–7 seconds per lesion) at Tulane Medical Center from July 2020 to January 2021. Esophageal temperature was monitored throughout the procedure using a temperature probe and patients underwent EGD the following day. Small ulcers, nonbleeding erosions, erythema, and/or esophagitis were considered positive EGD findings.

Results

Mean age was 64.9 years; 46.5% of the patients were female. Eleven patients had positive EGD findings (group 1) and 32 patients had normal EGD (group 2). There was no statistical difference in mean esophageal peak temperature between group 1 and group 2 (43.9°C ± 2.9°C and 42.5°C ± 2.3°C, respectively, P = .17). There was no association between positive EGD results and esophageal temperature during PVI. Mean baseline esophageal temperature was similar in both groups (36.1°C, P = .78). Average contact force (P = .53), ablation time (P = .67), age (P = .3096), sex (P = .4), body mass index (P = .14), and other comorbidities did not correlate with positive endoscopy results. We found positive correlation between the distance of the left atrium (LA) to esophagus and positive EGD (P = .0001).

Conclusion

EI during HPSD PVI does not correlate to esophageal temperature changes during ablation. However, esophageal injury does correlate to a shorter proximity of the esophagus to the LA.

Meta-analysis comparing outcomes of high-power short-duration and low-power long-duration radiofrequency ablation for atrial fibrillation

OBJECTIVE

High power short duration (HPSD) ablation strategy is proposed to be more effective than low power long duration (LPLD) for radiofrequency ablation of atrial fibrillation. Although small trials abound, data from a large cohort are lacking. This meta-analysis compares all the existing studies comparing these two approaches to evaluate perceived advantages of one over the other.

METHODS

A systematic search of PubMed, EMBASE, and Cochrane databases identified studies comparing HPSD to LPLD ablation. All the analyses used the random-effects model.

RESULTS

Ablation settings varied widely across 20 studies comprising 2,136 patients who underwent HPSD and 1,753 patients who underwent LPLD. The pooled incidence of atrial arrhythmia recurrence after HPSD ablation was 20% [95% confidence interval (CI): 0.16-0.25; I2=88%]. Atrial arrhythmia recurrences were significantly less frequent with HPSD ablation (incidence risk ratio=0.66; 95% CI: 0.49-0.88; I2=72%; p=0.004). Procedural, fluoroscopy, and ablation times were significantly shorter with HPSD ablation. First-pass pulmonary vein isolations (PVIs) were significantly more [odds ratio (OR)=2.94; 95% CI: 1.50-5.77; I2=89%; p=0.002), and acute pulmonary vein reconnections (PVRs) were significantly lesser (OR=0.41; 95% CI: 0.28-0.62; I2=62%; p<0.001) in the HPSD group. Although radiofrequency energy was significantly higher, esophageal thermal injuries (ETI) were lower with HPSD ablation. Acute complications, including steam-pops, were rare and statistically similar in both the groups.

CONCLUSION

HPSD ablation enables faster first-pass PVI with fewer PVRs, similar ETI rates, rare collateral damage, and lower recurrence of atrial arrhythmia in the long term than LPLD. Randomized controlled studies with a larger cohort are indicated both to confirm the benefit of HPSD ablation and standardize the ablation protocol.

Assessment of High-Power Catheter Ablation in Patients With Atrial Fibrillation: A Meta-Analysis

Background: High-power radiofrequency (RF) catheter ablation was considered as a promising alternative strategy to conventional-power ablation in the treatment of patients with atrial fibrillation (AF). This study sought to compare the efficacy and safety of high-power energy delivery to that of conventional-power setting in AF catheter ablation. Methods: We performed a systematic review of relevant literature in Pubmed, Embase, Cochrane library, and Google Scholar database. Sixteen eligible studies totaling 3,307 patients (1,929 for high-power ablation; 1,378 for conventional-power ablation) met inclusion criteria. Results: During a median 12 month follow-up, high-power ablation showed a significantly higher AF/atrial tachycardia-free survival rate in comparison with conventional-power ablation (risk ratio [RR] 1.09, 95% CI 1.02 to 1.15, p = 0.008). Notably, a high-power strategy convincingly decreased the procedure time (weighted mean difference [WMD] -46.11 min, 95% CI -59.15 to -33.07, p < 0.001) and RF ablation time (WMD -19.19 min, 95% CI -24.47 to -13.90, p < 0.001), along with reduced fluoroscopy time (WMD -7.82 min, 95% CI -15.13 to -0.68, p = 0.036). In addition, there was no perceptible difference in the potential risk of procedure-related complications between these two approaches (RR 0.81, 95% CI 0.48 to 1.37, p = 0.428). Conclusions: High-power RF catheter ablation was associated with an improvement in long-term sinus rhythm maintenance for treatment of AF, without exacerbating the risk of adverse events during the procedure. Impressively, high-power pulmonary vein isolation had the potential to shorten the application duration and minimize fluoroscopic exposure.

Efficacy and Safety of High-Power Short-Duration Radiofrequency Catheter Ablation of Atrial Fibrillation

Introduction: Whereas, high-power short-duration (HPSD) radiofrequency (RF) ablation is generally used in atrial fibrillation (AF) catheter ablation (CA), its efficacy, safety, and influence on autonomic function have not been well established in a large population. This study compared HPSD-AFCA and conventional power (ConvP)-AFCA in propensity score matched-population.

Methods: In 3,045 consecutive patients who underwent AFCA, this study included 1,260 patients (73.9% male, 59 ± 10 years old, 58.2% paroxysmal type) after propensity score matching: 315 in 50~60W HPSD group vs. 945 in the ConvP group. This study investigated the procedural factors, complication rate, rhythm status, and 3-month heart rate variability (HRV) between the two groups and subgroups.

Results: Procedure time was considerably short in the HPSD group (135 min in HPSD vs. 181 min in ConvP, p < 0.001) compared to ConvP group, but there was no significant difference in the complication rate (2.9% in HPSD vs. 3.7% in ConvP, p = 0.477) and the 3-month HRV between the two groups. At the one-year follow-up, there was no significant difference in rhythm outcomes between the two groups (Overall, Log-rank p = 0.885; anti-arrhythmic drug free, Log-rank p = 0.673). These efficacy and safety outcomes were consistently similar irrespective of the AF type or ablation lesion set. The Cox regression analysis showed that the left atrium volume index estimated by computed tomography (HR 1.01 [1.00–1.02]), p = 0.003) and extra-pulmonary vein triggers (HR 1.59 [1.03–2.44], p = 0.036) were independently associated with one-year clinical recurrence, whereas the HPSD ablation was not (HR 1.03 [0.73–1.44], p = 0.887).

Conclusion: HPSD-AFCA notably reduced the procedure time with similar rhythm outcomes, complication rate, and influence on autonomic function as ConvP-AFCA, irrespective of the AF type or ablation lesion set.

Acute and long-term efficacy of ablation index-guided higher power shorter duration ablation in patients with atrial fibrillation: A prospective registry

BACKGROUND

Theoretically, targeting the same ablation index (AI) using higher power may achieve the same lesion size with a shorter ablation time. We evaluated the acute and long-term efficacy of higher-powered ablation guided by ablation index (HPAI) compared with conventional-powered ablation guided by AI (CPAI) for pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF).

METHODS

Drug refractory symptomatic AF patients who had been ablated with 40 W on the anterior/roof segments and 30 W on the posterior/inferior/carina segments were enrolled (HPAI group). We compared the HPAI group with the CPAI group who were ablated with 30 W on the anterior/roof segments and 25 W on the posterior/inferior/carina segments. The same AI was targeted (≥450 on the anterior/roof segments and ≥350 on the posterior/inferior/carina segments). We compared ablation time, acute pulmonary vein reconnection (PVR) and 1-year AF recurrence between the two groups.

RESULTS

A total of 118 patients were included (86 in the HPAI group and 32 in the CPAI group, paroxysmal AF, 73%). There was no significant difference in the acute PVR rate between the HPAI and the CPAI groups (3.7% vs. 4.2%, P = .580) with a 41% reduction in ablation time for PVI (38.7 ± 8.3 vs. 65.8 ± 13.7 minutes, P < .001). The 1-year AF recurrence rate was not significantly different between HPAI and CPAI groups (12.8% vs. 21.9%, Log-rank P = .242). There were no major complications in either group.

CONCLUSIONS

Increased power during AF ablation, using the same AI targets, reduced the procedure and ablation times, and showed a comparable acute and long-term outcome without compromising safety.

CLINICAL TRIAL REGISTRATION

https://www.clinicaltrials.gov. Unique identifier: NCT04379557.

Regional differences in the predictors of acute electrical reconnection following high-power pulmonary vein isolation for paroxysmal atrial fibrillation

BACKGROUND

Acute pulmonary vein reconnection (PVR) is associated with long procedure times and large radiofrequency (RF) energy delivery during pulmonary vein isolation (PVI). Although the efficacy of high-power PVI (HP-PVI) has been recently established, the determinants of acute PVR following HP-PVI remain unclear.

METHODS

We evaluated data on 62 patients with paroxysmal atrial fibrillation undergoing unipolar signal modification (USM)-guided HP-PVI. A 50-W RF wave was applied for 3-5 seconds after USM. In the segments adjacent to the esophagus (SAEs), the RF time was limited to 5 seconds. Each circle was subdivided into six regions (segments), and the possible predictors of acute PVR, including minimum contact force (CFmin), minimum force-time integral (FTImin), minimum ablation index (AImin), minimum impedance drop (Imp-min), and maximum inter-lesion distance (ILDmax), were assessed in each segment.

RESULTS

We investigated 1162 ablations in 744 segments (including 124 SAEs). Acute PVR was observed in 21 (17%) SAEs and 43 (7%) other segments (P = .001). The acute PVR segments were characterized by significantly lower CFmin, FTImin, AImin, and Imp-min values in the segments other than the SAEs and larger ILDmax values in the SAEs. Furthermore, lower Imp-min and larger ILDmax values independently predicted acute PVR in the segments other than the SAEs and SAEs (odds ratios 0.90 and 1.39 respectively). Acute PVR was not significantly associated with late atrial fibrillation recurrence.

CONCLUSIONS

Avoiding PVR remains a challenge in HP-PVI cases, but it might be resolved by setting the optimal target impedance drop and lesion distance values.

Influence of power setting on superior vena cava potential during right pulmonary vein isolation

PURPOSE

High-power short-duration (HP-SD) ablation could reduce collateral tissue damage by shortening the conductive heating phase. However, it is difficult to evaluate the transmural effect of ablation lesions during pulmonary vein isolation (PVI) procedures. The present study aimed to evaluate the change in superior vena cava (SVC) potential delay as a surrogate marker of collateral tissue damage during right PVI, which is adjacent to SVC.

METHODS

Out of 250 consecutive patients who underwent PVI, 86 patients in whom SVC potential during sinus rhythm was recorded both before and after right PVI were analyzed. In 46 of the patients, an HP-SD setting of 45-50 W was used (HP-SD group). In the remaining 40 patients, a conventional power setting of 20-30 W was used (conventional group). We compared the change in SVC potential delay after right PVI, radiofrequency energy, and mean contact force in the anterior-superior right PVI line, which was close to the posterior aspect of SVC, between the two groups.

RESULTS

Although the total delivered radiofrequency energy (2,924 J vs. 2,604 J) and the mean contact force (18.5 g vs. 16.0 g) in the SVC overlapping area did not differ, the change in SVC potential delay after right PVI was significantly longer in the conventional group compared to the HP-SD group (5.0 ms vs. 0.0 ms, p < 0.001).

CONCLUSIONS

The changes in SVC potential delay after right PVI might be a surrogate marker of collateral tissue damage according to the used energy settings.

The superiority of high-power short-duration radiofrequency catheter ablation strategy for atrial fibrillation treatment: A systematic review and meta-analysis study

BACKGROUND

Radiofrequency catheter ablation (RFCA) using the high-power short duration (HPSD) results in better ablation lesion formation in the swine model. This systematic review and meta-analysis purposed to investigate the safety and efficacy profile between HPSD and low-power long-duration (LPLD) ablation strategies to treat atrial fibrillation (AF) patients.

METHODS

We completed the literature review after identifying the relevant articles comparing HPSD and LPLD ablation methods for AF recorded in ClinicalTrials.com, CENTRAL, PubMed, and ScienceDirect until February 2021. The overall effects were calculated using pooled risk ratio (RR) and mean difference (MD) for categorical and continuous data, respectively. We also estimated the 95% confidence interval (CI).

RESULTS

The HPSD strategy took shorter procedure time (MD = -33.75 min; 95% CI = -44.54 to -22.97; P < .01), fluoroscopy time (MD = -5.73 min; 95% CI = -8.77 to -2.70; P < .001), and ablation time (MD = -17.71; 95% CI = -21.02 to -14.41) than LPLD strategy. The HPSD RFCA was correlated with lower risk of esophageal thermal injury (RR = 0.75; 95% CI = 0.59 to 0.94; P = .02). The HPSD method resulted in higher first-pass pulmonary vein isolation (PVI) (RR = 1.36; 95% CI = 1.13 to 1.64; P < .01), lower PV reconnection (RR = 0.47; 95% CI = 0.34 to 0.64; P < .01), and lower recurrent AF (RR = 0.72; 95% CI = 0.54 to 0.96; P = .02) than LPLD strategy.

CONCLUSION

HPSD RFCA was superior to the conventional LPLD RFCA in terms of safety and efficacy in treating AF patients.

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.

The impacts of contact force, power and application time on ablation effect indicated by serial measurements of impedance drop in both conventional and high-power short-duration ablation settings of atrial fibrillation

Background

This study aimed to clarify the interrelationship and additive effects of contact force (CF), power and application time in both conventional and high-power short-duration (HPSD) settings.

Methods

Among 38 patients with paroxysmal atrial fibrillation who underwent first-time pulmonary vein isolation, 787 ablation points were collected at the beginning of the procedure at separate sites. Energy was applied for 60 s under power outputs of 25, 30 or 35 W (conventional group), or 10 s when using 50 W (HPSD group). An impedance drop (ID) of 10 Ω was regarded as a marker of adequate lesion formation.

Results

ID ≥ 10 Ω could not be achieved with CF < 5 g under any power setting. With CF ≥ 5 g, ID could be enhanced by increasing power output or prolonging ablation time. ID for 30 and 35 W was greater than for 25 W (p < 0.05). Ablation with 35 W resulted in greater ID than with 30 W only when CF of 10–20 g was applied for 20–40 s (p < 0.05). Under the same power output, ID increased with CF level at different time points. The higher the CF, the shorter the time needed to reach ID of 10 Ω and maximal ID. ID correlated well with ablation index under each power, except for lower ID values at 25 W. ID with 50 W for 10 s was equivalent to that with 25 W for 40 s, but lower than that with 30 W for 40 s or 35 W for 30 s.

Conclusions

CF of at least 5 g is required for adequate ablation effect. With CF ≥ 5g, CF, power output, and ablation time can compensate for each other. Time to reach maximal ablation effect can be shortened by increasing CF or power. The effect of HPSD ablation with 50 W for 10 s is equivalent to conventional ablation with 25 W for 40 s and 30–35 W for 20–30 s in terms of ID.

Atrial Fibrillation (Part 2) - Catheter Ablation

Após mais de 20 anos desde sua utilização inicial, a ablação por cateter se tornou um procedimento rotineiramente realizado para tratamento de pacientes com fibrilação atrial (FA). Fundamentado inicialmente no isolamento elétrico das veias pulmonares em pacientes com FA paroxística, subsequentes avanços no entendimento da fisiopatologia levaram a técnicas adicionais não só para obter melhores resultados, mas também para tratar pacientes com formas persistentes de arritmia, assim como pacientes com cardiopatia estrutural e insuficiência cardíaca.

Lesion size and adjacent tissue damage assessment with high power and short duration radiofrequency ablation: comparison to conventional radiofrequency ablation power setting

There is increased interest in creating high-power short duration (HPSD) ablation lesions in the field of atrial fibrillation (AF) radiofrequency ablation (RFA). We evaluated the lesion characteristics and collateral damage using two separate RFA protocols setting (HPSD: 50 W and 7 s vs control: 25 W and 30 s) in vitro model. Sixteen freshly killed porcine hearts were obtained, and the atrium and ventricle slabs were harvested for ablation. The each slabs were placed in a tissue bath with circulating 0.9% NaCl at maintained temperature 37 °C. RFA was performed with 4 mm tip irrigated force sensing catheter. All lesions were ablated under recording the electrical parameters using with Ensite Navx system (St. Jude Medical, St. Paul, Minnesota). After RFA, lesion characteristics were assessed for each lesion. Thirty-five lesions were made for each ablation protocol (total 70 lesions for analysis). Ablation parameters were similar between two groups (HPSD vs control; impedance drop (Ω): 34.2 ± 13.1 vs 36.1 ± 8.65 P = 0.49, contact force (g): 13.9 ± 4.37 vs 14.6 ± 5.09, P = 0.51, lesion size index: 4.8 ± 0.52 vs 4.73 ± 0.59, P = 0.62). Although the lesion volume was similar, the HPSD ablation creates wider but more shallower lesions compared to control group (HPSD vs control; lesion volume: 29.6 ± 18.1 mm³ vs 35.5 ± 17.1 mm³ P = 0.16, lesion diameter: 4.98 ± 0.91 mm vs 4.45 ± 0.74 mm P = 0.0095, lesion depth: 2.2 ± 0.76 mm vs 2.8 ± 1.56 mm P = 0.046). Of these, 38 lesions were assessed for adjacent tissue damage and adjacent tissue damages were more frequent seen in control group (HPSD vs control; 1/19 (5.26%) vs 6/19 (31.5%), P = 0.036). Effective lesions were made with HPSD, thereby reducing RFA procedure time. Although the lesion volume was similar between two groups, collateral damage was less seen in HPSD group attributed by lesion characteristics.

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.

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.

Comparison of high-power short-duration and low-power long-duration radiofrequency ablation for treating atrial fibrillation: Systematic review and meta-analysis

Background

High power shorter duration (HPSD) ablation seen to increase efficacy and safety treating of atrial fibrillation (AF); however, comparative data between HPSD and low power longer duration (LPLD) ablation are limited.

Hypothesis

We thought that HPSD might bring more clinical benefits. The aim of this meta‐analysis was to evaluate the clinical benefits of HPSD in patients with AF.

Methods

The Medline, PubMed, Embase, and the Cochrane Library databases were searched for studies comparing HPSD and LPLD ablation.

Results

Ten trials with 2467 patients were included in the analysis. Pooled analyses demonstrated that HPSD showed a benefit of first‐pass pulmonary vein isolation (PVI) (risk ratio [RR]: 1.20; 95% confidence interval [CI]: 1.10‐1.31, P < .001) and recurrence of atrial arrhythmias (RR: 0.73; 95% CI: 0.58‐0.91, P = .005). Additionally, HPSD could reduce procedural time (weighted mean difference [WMD]: −42.93; 95% CI, −58.10 to −27.75, P < .001), ablation time (WMD: −21.01; 95% CI: −24.55 to −17.47, P < .001), and fluoroscopy time (WMD: −4.11; 95% CI: −6.78 to −1.45, P < .001). Moreover, major complications and esophageal thermal injury (ETI) were similar between two groups (RR: 0.75; 95% CI: 0.44‐1.30, P = .31) and (RR: 0.57; 95% CI: 0.21‐1.51, P = .26).

Conclusions

HPSD was safe and efficient for treating AF. Compared with LPLD, HPSD was associated with advantages of procedural features, higher first‐pass PVI and reducing recurrence of atrial arrhythmias. Moreover, major complications and ETI were similar between two groups.

Catheter ablation for atrial fibrillation: current indications and evolving technologies

Catheter ablation for atrial fibrillation (AF) has emerged as an important rhythm-control strategy and is by far the most common cardiac ablation procedure performed worldwide. Current guidelines recommend the procedure in symptomatic patients with paroxysmal or persistent AF who are refractory or intolerant to antiarrhythmic drugs. The procedure might also be considered as a first-line approach in selected asymptomatic patients. Data from large registries indicate that AF ablation might reduce mortality and the risk of heart failure and stroke, but evidence from randomized controlled trials is mixed. Pulmonary vein isolation using point-by-point radiofrequency or with the cryoballoon remains the cornerstone technique in AF ablation. Additional atrial ablation can be performed in patients with persistent AF, but its benefits are largely unproven. Technological advances in the past decade have focused on achieving durable vein isolation, reducing procedure duration and improving safety. Numerous exciting new technologies are in various stages of development. In this Review, we discuss the relevant data to support the recommended and evolving indications for catheter ablation of AF, describe the different ablation techniques, and highlight the latest advances in technology that aim to improve its safety and efficacy. We also discuss lifestyle modification strategies to improve ablation outcomes.

High-power short-duration radiofrequency ablation of typical atrial flutter

Background

High-power short-duration (HPSD) ablation has been explored for pulmonary vein isolation. Early data suggest similar efficacy with shorter procedure times and perhaps greater safety. Data are lacking on the use of this ablation strategy for other arrhythmias.

Objective

The purpose of this study was to evaluate the safety, efficacy, and clinical outcomes of HPSD ablation in patients with typical atrial flutter compared to those undergoing ablation with conventional settings.

Methods

Consecutive patients undergoing cavotricuspid isthmus (CTI) ablation using standard power settings were compared to those performed after transitioning to HPSD ablation. Demographics, procedural details, and ablation outcomes were prospectively collected. The primary endpoint was duration of radiofrequency energy delivery. Secondary endpoints were radiation duration and analgesia requirements.

Results

A total of 114 consecutive subjects undergoing CTI ablation (57 standard power, 57 HPSD) were included. HPSD ablation and electroanatomic mapping/contact force (EAM/CF) use were associated with 66% (95% confidence interval [CI] 58%–73%) and 50% (95% CI 37%–60%) shorter ablation times compared to standard power and not using EAM/CF, respectively. Patients in the HPSD group required 50 mcg less fentanyl relative to the standard ablation arm after adjusting for sex, age, and comorbidities (P = .048). At a median follow-up of 6 months, 4 patients (7%) in the standard arm had recurrence of atrial flutter, compared to none in HPSD group (P = .057).

Conclusion

HPSD is a safe and effective approach to CTI ablation. This strategy may reduce ablation time and analgesia requirements. Larger studies and longer follow-up are needed to further evaluate this strategy.

High-power, short-duration ablation during Box isolation for atrial fibrillation

BACKGROUND

It has been demonstrated that a high-power, short-duration (HPSD) ablation during pulmonary vein (PV) isolation is effective and safe. However, studies about the HPSD ablation during the posterior wall isolation, the Box isolation (BOXI), are limited. We evaluated the efficacy, feasibility, and safety of HPSD ablation during BOXI.

METHODS

One-hundred sixty patients with all types of atrial fibrillation underwent BOXI with HPSD ablation (n = 80) or conventional technique (n = 80). In the HPSD group, ablation was performed with 50 W and a target lesion size index of 5.0 using a contact force (CF) sensing catheter. Ablation near the esophagus was performed with 50 W for 5 seconds and a CF < 10 g. In the conventional group, ablation was performed with 30-40 W for 30 seconds, but 20 W near the esophagus.

RESULTS

The BOXI creation (26 ± 8 minutes vs 47 ± 17 minutes, P < .0001) and procedure (65 ± 12 minutes vs 87 ± 23 minutes, P < .0001) times were significantly shorter in the HPSD group than the conventional group. The number of pacing capture sites did not differ between the two groups. No complications including gastrointestinal symptoms occurred. The atrial tachyarrhythmia-free rate at 12-months after a single procedure was 86.3% in the HPSD group and 76.3% in the conventional group, respectively (P = .132). The incidence of PV reconnections and gaps in the lines during the second procedure did not differ between the two groups.

CONCLUSION

The BOXI with HPSD ablation is effective, feasible, and safe with short BOXI creation and procedure times without reducing the clinical outcomes.

Long-standing Persistent Atrial Fibrillation Ablation: How do You Perform it?

Catheter ablation of long-standing persistent atrial fibrillation (LSPAF) presents unique challenges and the lack of large body of evidence surrounding management makes for disagreement and different approaches for treatment. Outlined is a case example that offers a comprehensive approach to ablation in patients with LSPAF that consists of risk factor management, an ablation strategy, a rigorous trigger protocol and follow-up rhythm monitoring. The case presented highlights management of this difficult population as best guided by current evidence and our experience. Ablation treatment and management strategies will continue to evolve with further randomized data and the advent of improved ablation technologies.

Bipolar ablation's unique paradigm: Duration and power as respectively distinct primary determinants of transmurality and steam pop formation

Background

Bipolar radiofrequency (RF) ablation strategies are increasingly used, mainly to target deep myocardial reentrant circuits responsible for ventricular tachycardia that cannot be extinguished with traditional unipolar RF ablation. Because this strategy is novel, factors that affect lesion geometry and steam pop formation require further investigation.

Objective

To assess the effect of contact force, power, and time on the resulting lesion geometry and the risk of steam pop formation during bipolar RF ablation of thick myocardial tissue.

Methods

A custom ex vivo bipolar ablation model was used to assess lesion formation. A combination of parallel and perpendicular configurations of ablation catheters was used to create lesions by varying force (20g, 30g, or 40g), power (30 or 40 W), and time (20, 30, 45, or 60 seconds). Lesion dimensions and the incidence of steam pops were recorded and then analyzed with binary logistic regression and multiple linear regression.

Results

In bipolar ablation, lesion transmurality was most affected by the amount of time RF energy was applied. Durations longer than 20 seconds resulted in lesions deeper than half the tissue thickness. Steam pop formation was more frequent in thinner tissue, at longer ablation times, and at higher powers.

Conclusion

The parameters assessed in this ex vivo model could be used as guidelines for future in vivo work and clinical evaluation of interventricular septal bipolar ablation.

Catheter Ablation of Atrial Fibrillation: State of the Art and Future Perspectives

PURPOSE OF REVIEW

Atrial fibrillation (AF), the most common sustained arrhythmia, is associated with high rates of morbidity and mortality. Maintenance of stable sinus rhythm (SR) is the intended treatment target in symptomatic patients, and catheter ablation aimed at isolating the pulmonary veins provides the most effective treatment option, supported by encouraging clinical outcome data. A variety of energy sources and devices have been developed and evaluated. In this review, we summarize the current state of the art of catheter ablation of AF and describe future perspectives.

RECENT FINDINGS

Catheter ablation is a well-established treatment option for patients with symptomatic AF and is more successful at maintaining SR than antiarrhythmic drugs. Antral pulmonary vein isolation (PVI) as a stand-alone ablation strategy results in beneficial clinical outcomes and is therefore recommended as first-line strategy for both paroxysmal and persistent AF. While radiofrequency-based PVI in conjunction with a three-dimensional mapping system was for many years considered to be the "gold standard", the cryoballoon has emerged as the most commonly used alternative AF ablation tool, especially in patients with paroxysmal AF. Patients with persistent or long-standing persistent AF and with arrhythmia recurrence after previous PVI may benefit from additional ablation strategies, such as substrate modification of various forms or left atrial appendage isolation. New technologies and techniques, such as identification of the AF sources and magnetic resonance imaging-guided substrate modification, are on the way to further improve the success rates of catheter ablation for selected patients and might help to further reduce arrhythmia recurrence.

CONCLUSIONS

Pulmonary vein isolation is the treatment of choice for symptomatic patients with paroxysmal and persistent drug-refractory AF. The reconnection of previously isolated pulmonary veins remains the major cause of AF recurrence. Novel ablation tools, such as balloon technologies or alternative energy sources, might help to overcome this limitation. Patients with non-paroxysmal AF and with AF recurrence might benefit from alternative ablation strategies. However, further studies are warranted to further improve our knowledge of the underlying mechanisms of AF and to obtain long-term clinical outcomes on new ablation techniques.

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.

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

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

Gains in Paroxysmal Atrial Fibrillation Ablation Using a Standardized Workflow to Optimize Contact Force Technologies

Background

Catheter ablation technology has evolved rapidly in recent years. There is a need to understand the impact of these advances on efficiency, safety, and effectiveness in real-world populations. The objective of this study was to evaluate a standardized workflow that integrates a contact force (CF) catheter and stability module in an attempt to optimize efficiency and clinical outcomes of paroxysmal atrial fibrillation (PAF) ablation, and to compare the outcomes of this workflow with existing ablation technologies at a high-volume center.

Methods

Consecutive ablations for PAF from July 2013 - June 2016 were included. Radiofrequency (RF) ablations were performed with the ThermocoolSF Catheter (SF) through April 2014, after which a change was made to the ThermocoolSmarttouchCatheter (ST)with a standardized workflow. Cryoballoon ablations (CA) were performed with theArctic FrontAdvancebetween July 2013 and March 2016. Systematic collection of 12-month effectiveness data began in July 2014. Prior to that time, only acute outcomes and reablations were captured.

Results

Procedural data for 32 SF, 232 ST, and 59 CA procedures for PAF were available. Mean procedure times were similar across SF and CA, and moderately shorter with ST (p=0.0201). Fluoroscopy times were substantially reduced with ST (p<0.0001). Complication rates were low and similar across all cohorts (p=0.4744), whereas reablation rates were lowest in the ST cohort (p=0.0194).

Conclusions

PAF ablation using integrated CF and catheter stability technology with a systematic ablation workflow maylead to improvements in both procedural efficiency and reablation rates, without compromising patient safety.

Identification of Radiofrequency Ablation Catheter Parameters That May Induce Intracardiac Steam Pops: Direct Visualization of Elicitation in Reanimated Swine Hearts

Radiofrequency, a common ablation modality, is used clinically to terminate cardiac arrhythmias. With excessive heating, complications sometimes occur when the applied energy generates steam pops, which cause release of energy in the form of tissue and/or air emboli. In this study, we investigated numerous parameters potentially associated with intracardiac steam pops including (1) wattage, (2) catheter tip temperature, (3) catheter irrigation, (4) anatomic site, and (5) repeat ablations at a given site. Using unique Visible Heart® methodologies in reanimated swine hearts, we visualized 539 ablations; steam pops developed in 140 of these ablations. The incidence of steam pops significantly increased for both nonirrigated and irrigated ablations at 40 W (p < 0.005), and for nonirrigated ablations with catheter contact angles perpendicular to the tissue or that encompassed larger surface areas (p < 0.05). To minimize the incidence of steam pops, clinicians performing radiofrequency ablations must consider catheter parameters.

Wavelength and Fibrosis Affect Phase Singularity Locations During Atrial Fibrillation

The mechanisms underlying atrial fibrillation (AF), the most common sustained cardiac rhythm disturbance, remain elusive. Atrial fibrosis plays an important role in the development of AF and rotor dynamics. Both electrical wavelength (WL) and the degree of atrial fibrosis change as AF progresses. However, their combined effect on rotor core location remains unknown. The aim of this study was to analyze the effects of WL change on rotor core location in both fibrotic and non-fibrotic atria. Three patient specific fibrosis distributions (total fibrosis content: 16.6, 22.8, and 19.2%) obtained from clinical imaging data of persistent AF patients were incorporated in a bilayer atrial computational model. Fibrotic effects were modeled as myocyte-fibroblast coupling + conductivity remodeling; structural remodeling; ionic current changes + conductivity remodeling; and combinations of these methods. To change WL, action potential duration (APD) was varied from 120 to 240ms, representing the range of clinically observed AF cycle length, by modifying the inward rectifier potassium current (IK1) conductance between 80 and 140% of the original value. Phase singularities (PSs) were computed to identify rotor core locations. Our results show that IK1 conductance variation resulted in a decrease of APD and WL across the atria. For large WL in the absence of fibrosis, PSs anchored to regions with high APD gradient at the center of the left atrium (LA) anterior wall and near the junctions of the inferior pulmonary veins (PVs) with the LA. Decreasing the WL induced more PSs, whose distribution became less clustered. With fibrosis, PS locations depended on the fibrosis distribution and the fibrosis implementation method. The proportion of PSs in fibrotic areas and along the borders varied with both WL and fibrosis modeling method: for patient one, this was 4.2-14.9% as IK1 varied for the structural remodeling representation, but 12.3-88.4% using the combination of structural remodeling with myocyte-fibroblast coupling. The degree and distribution of fibrosis and the choice of implementation technique had a larger effect on PS locations than the WL variation. Thus, distinguishing the fibrotic mechanisms present in a patient is important for interpreting clinical fibrosis maps to create personalized models.

Atrial fibrillation ablation using very short duration 50 W ablations and contact force sensing catheters

Purpose

The optimal radiofrequency (RF) power and lesion duration using contact force (CF) sensing catheters for atrial fibrillation (AF) ablation are unknown. We evaluate 50 W RF power for very short durations using CF sensing catheters during AF ablation.

Methods

We evaluated 51 patients with paroxysmal (n = 20) or persistent (n = 31) AF undergoing initial RF ablation.

Results

A total of 3961 50 W RF lesions were given (average 77.6 ± 19.1/patient) for an average duration of only 11.2 ± 3.7 s. As CF increased from < 10 to > 40 g, the RF application duration decreased from 13.7 ± 4.4 to 8.6 ± 2.5 s (p < 0.0005). Impedance drops occurred in all ablations, and for patients in sinus rhythm, there was loss of pacing capture during RF delivery suggesting lesion creation. Only 3% of the ablation lesions were at < 5 g and 1% at > 40 g of force. As CF increased, the force time integral (FTI) increased from 47 ± 24 to 376 ± 102 gs (p < 0.0005) and the lesion index (LSI) increased from 4.10 ± 0.51 to 7.63 ± 0.50 (p < 0.0005). Both procedure time (101 ± 19.7 min) and total RF energy time (895 ± 258 s) were very short. For paroxysmal AF, the single procedure freedom from AF was 86% at 1 and 2 years. For persistent AF, it was 83% at 1 year and 72% at 2 years. There were no complications.

Conclusions

Short duration 50 W ablations using CF sensing catheters are safe and result in excellent long-term freedom from AF for both paroxysmal and persistent AF with short procedure times and small amounts of total RF energy delivery.

The Impact of Advances in Atrial Fibrillation Ablation Devices on the Incidence and Prevention of Complications

The number of patients with atrial fibrillation currently referred for catheter ablation is increasing. However, the number of trained operators and the capacity of many electrophysiology labs are limited. Accordingly, a steeper learning curve and technical advances for efficient and safe ablation are desirable. During the last decades several catheter-based ablation devices have been developed and adapted to improve not only lesion durability, but also safety profiles, to shorten procedure time and to reduce radiation exposure. The goal of this review is to summarise the reported incidence of complications, considering device-related specific aspects for point-by-point, multi-electrode and balloon-based devices for pulmonary vein isolation. Recent technical and procedural developments aimed at reducing procedural risks and complications rates will be reviewed. In addition, the impact of technical advances on procedural outcome, procedural length and radiation exposure will be discussed.