High-power Short-duration Radiofrequency Research Articles

Impact of High-Power Short-Duration Radiofrequency Ablation on Esophageal Temperature Dynamic.

High-power short-duration (HP-SD) radiofrequency ablation (RFA) has been proposed as a method for producing rapid and effective lesions for pulmonary vein isolation. The underlying hypothesis assumes an increased resistive heating phase and decreased conductive heating phase, potentially reducing the risk for esophageal thermal injury. The objective of this study was to compare the esophageal temperature dynamic profile between HP-SD and moderate-power moderate-duration (MP-MD) RFA ablation strategies. In patients undergoing pulmonary vein isolation, RFA juxtaposed to the esophagus was delivered in an alternate sequence of HP-SD (50 W, 8-10 s) and MP-MD (25 W, 15-20 s) between adjacent applications (distance, ≤4 mm). Esophageal temperature was recorded using a multisensor probe (CIRCA S-CATH). Temperature data included magnitude of temperature rise, maximal temperature, time to maximal temperature, and time return to baseline. In swine, a similar experimental design compared the effect of HP-SD and MP-MD on patterns of esophageal injury. In 20 patients (68.9±5.8 years old; 60% persistent atrial fibrillation), 55 paired HP-SD and MP-MD applications were analyzed. The esophageal temperature dynamic profile was similar between HP-SD and MP-MD ablation strategies. Specifically, the magnitude of temperature rise (2.1 °C [1.4-3] versus 2.0 °C [1.5-3]; P=0.22), maximal temperature (38.4 °C [37.8-39.3] versus 38.5 °C [37.9-39.4]; P=0.17), time to maximal temperature (24.9±7.5 versus 26.3±6.8 s; P=0.1), and time of temperature to return to baseline (110±23.2 versus 111±25.1 s; P=0.86) were similar between HP-SD and MP-MD ablation strategies. In 6 swine, esophageal injury was qualitatively similar between HP-SD and MP-MD strategies. Esophageal temperature dynamics are similar between HP-SD and MP-MD RFA strategies and result in comparable esophageal tissue injury. Therefore, when using a HP-SD RFA strategy, the shorter application duration should not prompt shorter intervals between applications.

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.

A novel local impedance algorithm and contact force sensing to guide high power short duration radiofrequency ablation is efficient and safe for circumferential pulmonary vein isolation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Local impedance (LI) drop can predict sufficient lesion formation during radiofrequency ablation (RF). Recently, a novel ablation catheter technology able to measure LI and contact force has been made available for clinical use. High power short duration (HPSD) RF ablation has been shown to be feasible for atrial fibrillation (AF) ablation with short procedure time. We used LI drop and plateau formation to guide duration of 50 Watt RF power applications for circumferential pulmonary vein isolation (PVI). Methods Consecutive patients with indication for de novo AF ablation (n = 32, age 65 ± 10 years) with paroxysmal (n = 16) or persistent (n = 16) AF underwent ultra high density 3D mapping of the left atrium and catheter ablation. Thereafter, ipsilateral PV encircling with 50 Watt RF-applications targeting an interlesion distance of ≤ 6mm and a contact force of 10-30g was performed. Duration of HPSD RF application between 7-15s was guided by impedance drop &amp;gt;20 Ohm and plateau formation of LI. Further ablation strategy was left to the investigator’s discretion. Esophageal temperature measurement was performed using a three thermistor catheter with temperature cut off 39.0°C. In case of temperature rise or very near esophageal contact to the circumferential line, RF application time was shortened to 7s. Patients underwent adenosine testing after PVI. Previously we performed all types of AF ablation using an LI guided HPSD ablation without contact force measurement capability in 80 patients. Results Complete PVI was achieved in all pts with only 13.5 ± 4.3 min cumulative RF application duration and an ablation procedure duration of 46.5 ± 10.4 min with the novel LI measuring catheter. First-pass isolation of ipsilateral veins was achieved in 75% of circles. Recurrence of PV conduction during waiting period (20min) and adenosine testing occured in 25% of circles, and was reablated in most patients with a single spot of HPSD application. Using 94 ± 36 RF application per patient, mean maximum LI drop was 23.6 ± 4.0 Ohm. Reconnected fibers were associated with low LI drop due to instability of contact in most cases due to breathing in case of difficult sedation of the patients. No serious complications occurred in all 32 pts using HPSD with the novel contact force catheter design. Conclusion Guiding of HPSD RF ablation by LI is highly efficient and safe. A novel local impedance algorithm in combination with contact force sensing enable short PVI times with low early recurrence of PV conduction. Prediction of permanent lesions seems possible and the only limitation seems to be unstable RF catheter contact due patients breathing. Follow up have to be waited.

Pulmonary vein isolation for paroxysmal atrial fibrillation using high-power short duration radiofrequency or second-generation cryoballoon ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background Differences in the left atrial (LA) tissue loss can occur following different pulmonary vein isolation (PVI) techniques. Purpose Our prospective study compared the biomarker, the LA mechanical, and the electrophysiological findings as indicators of LA myocardial damage after a high-power short duration (HPSD) with contact force radiofrequency catheter and second-generation cryoballoon (CB2) ablation of paroxysmal atrial fibrillation (AF). Methods :We enrolled 40 patients with paroxysmal AF [16 (40%) women, mean age = 55.9 ± 12.4 years] who underwent HPSD (n = 21) or CB2 (n = 19). Biomarker levels (hs-cTnT, CK-MB, hs-CRP, LDH) and the transport function of the LA by transthoracic echocardiography (TTE) were compared pre and post procedurally. High-density mapping (HDM) was performed in sinus rhythm using a multielectrode diagnostic catheter in each group to define isolated left atrial low voltage area (LVA; &amp;lt;0.2mV in bipolar voltage mapping). LA CT-angiography and HDM merge was used to calculate the post-PVI LVA and the LVA/LA surface ratio. Results Postablation hs-cTnT and hs-CRP levels were comparable in the ablation groups (HPSD: 1249 ± 469 and 9.53 ± 10.30 vs. CB2: 995 ± 280 and 12.36 ± 5.76, p = 0.065 and p = 0.732), while CK-MB and LDH levels were significantly higher following CB2 ablation (HPSD: 6.61 ± 2.62 and 349.9 ± 65.6 vs. CB2: 26.01 ± 6.88 and 451.6 ± 91.3, p &amp;lt; 0.001 and p &amp;lt; 0.001). The transport function of the LA did not change significantly by TTE after the procedure. Fractional Area Change at baseline and 3 months was 33.9 ± 13.8 and 33.5 ± 10.7 p = 0.9 in the HPSD group while 38.1 ± 8.6 and 35.3 ± 12.2 p = 0.9 in the CB2 group. LA Ejection Fraction measured in the two groups (before and 3-month post-procedure): HPSD: 51.2 ± 20.5% and 49.5 ± 14.7%, p = 0.9, CB2: 49.7 ± 15.5% and 50.7 ± 13.3%, p = 0.8). Ablation time was comparable in the two groups (HPSD: 1676 ± 570 sec, CB2: 1495 ± 494 sec, p = 0.279), while fluoroscopy time and radiation exposure were significantly higher in the CB2 group (HPSD: 5.62 ± 4.31 min and 232 ± 406 cGycm2, CB2: 13.65 ± 5.18 min and 1819 ± 1669 cGycm2, p &amp;lt;0.001 and p &amp;lt;0.001). The LVA/LA surface ratio were: HPSD group: 8.37 ± 6.42% and CB2 group: 13.58 ± 8.92% (p = 0.007). At 12-month follow-up, the success rate, defined as freedom from AF/atrial tachycardia without antiarrhythmic drug was 80.1% (HPSD) and 84.2% (CB2) respectively. Conclusions The LA scar tissue was significantly higher following CB2 ablation, but did not affect medium-term efficacy. However, tissue loss did not reduce the transport function of the LA.

Efficacy and safety of 50-60 Watt high-power short-duration radiofrequency catheter ablation of atrial fibrillation: A propensity score matching study

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Although high-power short-duration (HPSD) radiofrequency (RF) energy is commonly utilized in atrial fibrillation (AF) catheter ablation (CA), its efficacy, safety, and autonomic neural effects have not yet been evaluated in a large patient number. We compared HPSD-AFCA and conventional power (ConvP)-AFCA after propensity score matching. Methods Among 3,221 consecutive AF ablation patients, we included 1,720 patients (74.4% male, 59 ± 10 years old, 56.5% paroxysmal type) who underwent AFCA after propensity score matching: 430 in 50∼60W HPSD group vs. 1,290 in the ConvP group. We evaluated the procedural factors, complication risk, rhythm outcome, and 3-month heart rate variability (HRV) between the two groups and subgroups. Results Procedure times were significantly shorter in the HPSD group (p &amp;lt; 0.001), but the complication rate (p = 0.088) and the 3rd-month HRV did not differ between the two groups. At the 12-month follow-up, rhythm outcomes did not differ between the two groups (Overall, Log-rank p = 0.212; anti-arrhythmic drug off Log rank p = 0.246). These efficacy and safety outcomes were consistently similar regardless of the AF type or ablation lesion set. In the Cox regression analysis, the left atrium volume index measured by computed tomography (HR 1.009 [1.003-1.015]), p = 0.005) and extra-pulmonary vein triggers (HR 1.587 [1.033-2.440], p = 0.035) were independently associated with 1-year clinical recurrence, while the HPSD strategy was not (HR 1.188 [0.903-1.564], p = 0.218). Conclusions HPSD-AFCA significantly shortened the procedure time with similar rhythm outcomes, complication risks, and autonomic neural effects as ConvP-AFCA, regardless of the AF type or ablation lesion set. Abstract Figure.

High-power short-duration radiofrequency ablation for atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction In recent times, high-power short-duration (HPSD) radiofrequency ablation (RFA) has emerged as an alternative strategy for pulmonary vein isolation (PVI) in atrial fibrillation (AF). Purpose We aimed to compare HPSD approach and conventional, ablation-index (AI) guided PVI using contact force sensing ablation catheters in respect of efficacy, safety, procedural characteristics, and outcome. Methods A total of 184 consecutive AF patients with first PVI were enrolled (age: 60 ± 11 years, paroxysmal: 56.5%, persistent: 43.5%) between November 2016 and December 2019. An ablation protocol of 50W energy with 15-20 g contact force was used for a duration of 8-12 sec based on the loss of capture concept in the HPSD group (n = 91) meanwhile, PVI was achieved according to the conventional power settings (posterior wall 25W, AI: 400, anterior wall 35W, AI: 550 ) in the control group (n = 93). During 1-year follow-up, documented AF for more than 30 seconds was considered as recurrence. Results Radiofrequency time and procedural time were significantly shorter using HPSD ablation (26.0 ± 12.7 min vs. 42.9 ± 12.6 min, p &amp;lt; 0.001, and 91 ± 30.1 min vs. 105.3 ± 28 min, p &amp;lt; 0.001). The HPSD strategy significantly lowered fluoroscopy time and radiation dose (5.47 ± 4.07 min vs. 8.15 ± 10.04 min, p = 0.019, and 430.2 ± 534.06 cGycm2 vs. 604.2 ± 633.9 cGycm2, p = 0.046). The HPSD group showed significantly less arrhythmia recurrence during 1-year follow-up with 76.9% of patients free from AF compared to 66.7% in the control group (p = 0.037). No pericardial tamponade, periprocedural thromboembolic complication, or atrio-oesophageal fistula occurred in the HPSD group. We observed 2 pericardial tamponade and 1 periprocedural stroke in the control group. Conclusions HPSD RFA for AF was demonstrated to be safe, and lead to significantly improved 1-year outcome in our mixed patient population. HPSD protocol significantly shortened procedural and radiofrequency time with decreased fluoroscopy time and radiation exposure.

The efficacy of high-power short-duration radiofrequency for atrial fibrillation ablation: A protocol for systematic review and meta-analysis.

Background:Studies comparing data between the high-power short-duration radiofrequency (HPSR) and low power longer duration therapy were limited and inconsistent. Therefore, we conduct a high-quality systematic review and meta-analysis to assess the efficacy and safety of HPSR on outcomes for patients with atrial fibrillation (AF).Methods:The online literature is searched using the following combination of medical subject heading terms: “high-power” OR “high power” AND “radiofrequency” AND “atrial fibrillation.” MEDLINE (PubMed), EMBASE (OVID), Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science (ISI database) will be searched without any language restrictions. All clinical trials to assess the efficacy and safety of HPSR in the treatment of atrial fibrillation will be considered eligible for analysis. The present study will be performed by Review Manager Software (RevMan Version 5.3, The Cochrane Collaboration, Copenhagen, Denmark). Ethical approval and patient consent are not required because this study is a literature-based study.Results:This study expects to provide credible and scientific evidence for the efficacy and safety of HPSR on outcomes for patients with AF.Registration number:10.17605/OSF.IO/WAEBN.

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.

Proactive Esophageal Cooling Protects Against Thermal Insults During High-Power Short-Duration Radiofrequency Ablation

Background: Atrioesophageal fistula (AEF) is a severe complication of left atrial radiofrequency (RF) ablation for the treatment of atrial fibrillation. Proactive cooling with a novel cooling device has been shown to significantly reduce thermal injury, with no AEFs yet encountered after thousands of treatments worldwide. Computer modeling suggested that lethal temperatures could be avoided with moderate-power and moderate-duration RF ablation. We aimed to evaluate the effects of proactive cooling during high-power short-duration (HPSD) ablation, and compare the computed results to clinical data and recently published experimental data. Methods: A computer model accounting for the left atrium and esophagus including the active cooling device was created. We used both the Arrhenius equation and 50oC isotherm to estimate the esophageal thermal damage during 50 W, 10 second and 90 W, 4 second RF ablations. Results: Under control conditions, temperatures across the esophageal wall exceeded the lethal isotherm, in agreement with recent experimental data. With proactive esophageal cooling in place, temperatures in the esophageal tissue were significantly reduced, with the resulting fraction of esophageal damage reduced by 74% under 50 W and 10 seconds of ablation, and by 82% under 90 W and 4 seconds of ablation. Esophageal damage was restricted to the epi-esophageal region, sparing the remainder of the esophageal tissue, including the mucosal surface. Conclusions: Proactive esophageal cooling significantly reduced temperatures and the resulting fraction of damage in the esophagus during HPSD ablation. These findings offer a mechanistic rationale explaining the absence of AEF encountered to date using proactive esophageal cooling.

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

BackgroundHigh-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.ObjectiveThe 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.MethodsConsecutive 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.ResultsA 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).ConclusionHPSD 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.

Impact of High-Power Short-Duration Radiofrequency Ablation on Long-Term Lesion Durability for Atrial Fibrillation Ablation.

The goal of this study was to compare lesion durability between high-power short-duration (HP-SD) and moderate-power moderate-duration (MP-MD) ablation strategies. HP-SD radiofrequency ablation (RFA) was developed to improve pulmonary vein isolation (PVI) by reducing the effect of catheter instability inherent to MP-MD ablation strategies. However, its long-term effect on lesion durability for the treatment of atrial fibrillation is unknown. Patients with atrial fibrillation (n=112) underwent PVI using HP-SD ablation (45 to 50 W, 8 to 15 s) with contact force-sensing open irrigated catheter. Cavotricuspid isthmus, mitral annular, and roof lines were permitted. A control group (n=112) underwent ablation using MP-MD ablation (20 to 40 W, 20 to 30 s) with similar technology. Chronic PV reconnection was examined in patients who required a redo procedure (HP-SD ablation, n=18; MP-MD ablation, n=23). The rate of PVI at the completion of the initial encirclement was similar between the HP-SD and MP-MD ablation strategies (90.2% vs. 83.0%; p=0.006). The HP-SD strategy required shorter RFA time (17.2 ± 3.4min vs. 31.1± 5.6min; p<0.001). The incidence of chronic PV reconnection was lower with HP-SD ablation (16.6% vs. 52.2%; p=0.03). Areas of chronic reconnection were associated with catheter motion≥1mm for≥50% application duration. In a higher proportion of HP-SD applications, catheter motion was<1mm during≥50% duration (88.6% vs. 72.8%; p<0.001), allowing energy delivery with greater stability. Both ablation strategies were effective for cavotricuspid isthmus; however, the HP-SD strategy was less effective for mitral annular lines, requiring ablation at lower power for longer duration to avoid steam pops. HP-SD ablation may improve PVI durability, and it shortens RFA time. However, ablation in thicker myocardium often requires lower power applied for longer duration, allowing deeper lesions without tissue overheating.

P565First characterization of high-power short-duration radiofrequency ablation with remote magnetic navigation assistance

Abstract Funding Acknowledgements MEYS- CR (ref#LQ1605 and LM2015062) Background/Introduction High-power short-duration (HPSD) radiofrequency (RF) ablation relies on the application of intense thermal fields for a carefully restricted time, in order to quickly obtain deep but precise lesions that spare the structures surrounding the heart. The approach is still under evaluation across different therapies and catheter technologies. To the present day there is no available characterization of HPSD ablation supported by remote magnetic navigation (RMN). Purpose To describe the safety issues regarding HPSD ablation in atria and ventricles with RMN systems, while characterizing the thermal lesion size and continuity in an acute closed-chest swine model. Methods The animal trial was divided in two arms (left ventricular and atrial). 10 female large white pigs (6-month-old weight 55-65 kg) were employed in each arm. Endocardial electroanatomical mapping and ablation were performed with RMN assistance to provide stable contact and flexible maneuvering. The ventricular cohort was divided in 5 power settings (30-40-50-60-70W). Multiple RF applications (10 ca./animal) were delivered until a pop occurred or up to 60s. In the atrial cohort the animals were divided by a combination of power/application time (50W/20s – 70W/10s – 90W/4s). Intracaval right atrial ablation lines and postero-lateral left atrial lines were performed in a point-by-point fashion (ca. 4mm distance). Irrigation rate was 30ml/min. The ventricular lesions were measured via software after 9.4T MRI of fixed hearts. The atrial lesions were measures during pathological examination after explanation. Results In the ventricular arm, we obtained a safety calibration curve linking the imposed power setting to the maximal time of application. The time before a pop decreased non-linearly from 60s down to 17.69 ± 8.21 s at 70W. No statistically significant differences were observed when comparing lesions depth, width and volume among the selected power settings. In the atrial arm we observed on the post-ablation maps a significant decrease of intracaval lesions (i.e. area with bipolar voltage &amp;lt;1.5mV) width (17.57 ± 1.89 mm for 50W/4s down to 10.16 ± 1.56 mm for 90W/4s). Pericardial, pleural and aortic damages were visible across all the employed settings, with less pronounced alterations for 90W/4s. Transmural lesions were visible both on the right and left atrium, with evident gaps for 50W/20s. Conclusion The presented work assesses for the first time the safety limits of HPSD ablation on healthy ventricular myocardium. We provide a calibration curve for faster RF ablation with comparable lesion features. Furthermore, we expanded the previously reported application in the atrium adding the benefits of stable controlled contact provided by RMN systems. We highlighted the benefits (e.g. faster, continuous and localized lesion formation) and risks for peripheral structures using HPSD ablation for supraventricular tachycardia interventions. Abstract Figure.

Continuous ablation improves lesion maturation compared with intermittent ablation strategies.

Interrupted ablation is increasingly proposed as part of high-power short-duration radiofrequency ablation (RFA) strategies and may also result from loss of contact from respiratory patterns or cardiac motion. To study the extent that ablation interruption affects lesions. In ex vivo and in vivo experiments, lesion characteristics and tissue temperatures were compared between continuous (group 1) and interrupted (groups 2 and 3) RFA with equal total ablation duration and contact force. Extended duration ablation lesions were also characterized from 1 to 5 minutes. In the ex vivo study, continuous RFA (group 1) produced larger total lesion volumes compared with each interrupted ablation lesion group (273.8 ± 36.5 vs 205.1 ± 34.2 vs 174.3 ± 32.3 mm3 , all P < .001). Peak temperatures for group 1 were higher at 3 and 5 mm than groups 2 and 3. In vivo, continuous ablation resulted in larger lesions, greater lesion depths, and higher tissue temperatures. Longer ablation durations created larger lesion volumes and increased lesion depths. However, after 3 minutes of ablation, the rate of lesion volume, and depth formation decreased. Continuous RFA delivery resulted in larger and deeper lesions with higher tissue temperatures compared with interrupted ablation. This study may have implications for high-power short duration ablation strategies, motivates strategies to reduce variations in ablation delivery, and provides an upper limit for ablation duration beyond which power delivery has diminishing returns.

Ablation Approaches and Imaging Modalities to Lower Risk of Atrioesophageal Injury During Catheter Ablation for Atrial Fibrillation

Atrioesophageal fistula (AEF) is a rare yet catastrophic complication of atrial fibrillation (AF) ablation. Limited data exists on measures to prevent AEF. This review focuses on AF ablation approaches, esophageal protective strategies, and imaging modalities that can be utilized to reduce the risk of AEF. AEF has been reported to occur in less than 0.1% of AF ablation cases. Left untreated, it is associated with 100% mortality. Diagnosing AEF requires a high index of suspicion as symptoms are usually nonspecific. Several AF ablation techniques might reduce the risk of esophageal thermal injury (ETI): high-power short-duration radiofrequency ablation, implementation of time-to-isolation ablation strategy with cryoablation, and electroporation. Various esophageal protective approaches have been investigated. Although luminal esophageal temperature monitoring is widely used, data on its efficacy is conflicting. Esophageal cooling and esophageal deviation strategies have been shown to be effective in reducing the risk of ETI. Late gadolinium enhancement magnetic resonance imaging (LGE-MRI) is a noninvasive imaging modality that seems to have high sensitivity for detecting and quantifying the degree of ETI. Variable approaches have been reported to reduce the risk of esophageal injury. These approaches focus mainly on modulating ablation parameters and esophageal luminal temperature. Imaging modalities such as LGE-MRI can potentially identify early signs of ETI. Electroporation is a promising ablation technique that exhibits high tissue selectivity and can potentially reduce risk of esophageal injury.

Feasibility and safety of pulmonary vein isolation by high-power short-duration radiofrequency application: short-term results of the POWER-FAST PILOT study.

Pulmonary vein (PV) isolation (PVI) by point-by-point radiofrequency application (PPRF) results in longer procedures than that achieved by single-shot ablation techniques. In addition, it is associated with significant risk of oesophageal injury. The POWER-FAST pilot study evaluated the feasibility and safety of PVI by high-power short-duration (HPSD) PPRF. HPSD PPRF around the PVs was done in 48 consecutive patients with atrial fibrillation. Fifty watts was delivered until a predefined lesion index value was reached (LSI ≥ 5 or Abl-I ≥ 350) and 60 W during 7-10 s in the first 18 and last 30 patients, respectively. A control group of 47 consecutive patients who had undergone PVI before the HPSD group with conventional PPRF (30 W for 30 s) was included for reference. Echocardiography and oesophageal endoscopy was performed shortly after ablation in all patients. PVI of all targeted veins was achieved in 98% and 100% of patients of the conventional and HPSD groups, respectively (p = 0.59). Total radiofrequency time was 34 ± 11, 24 ± 8, and 15 ± 5 min in groups 30 W, 50 W, and 60 W (p < 0.001). Audible steam pops occurred in 4 out of 48 (8%) patients in the HPSD group, accounting for 4 (0.08%) out of 5 269 HPSD radiofrequency applications. No patient in the HPSD group developed pericardial effusion. The incidence of oesophageal lesions was 28%, 22%, and 0% in groups 30 W, 50 W, and 60 W, respectively (p = 0.007) CONCLUSIONS: PVI can be achieved with HPSD PPRF in most patients. This approach appears safe and associated with low risk of esophageal damage.

P1861Influence of thermal conductivity on esophageal protection with a cooling device during high-power short-duration radiofrequency ablation

Abstract Introduction Recent clinical data show that high-power, short-duration (HPSD) radiofrequency (RF) ablation can result in a similar esophageal injury rate as traditional low-power, long-duration (LPLD) ablation. Existing methods to prevent esophageal injury have yielded mixed results and can result in prolonged procedure time, potentially increasing the incidence of post-operative cognitive dysfunction. A new esophageal cooling device currently available for whole-body temperature modulation is being studied for the prevention of esophageal injury during LPLD RF ablation and cryoablation. We sought to develop a mathematical model of HPSD ablation in order to quantify the capability of this new esophageal cooling device to protect from esophageal injury under high-power conditions. Methods Using a model we developed of HPSD RF ablation in the left atrium, we measured the change in esophageal lesion formation and the depth of lesions (measured as percent transmurality) with the esophageal cooling device in place and operating at a temperature from 5°C to 37°C. Tissue parameters, including thermal conductivity, were set to average values obtained from existing literature, and energy settings were evaluated at 50W for between 5 and 10 seconds, and at 90W for a duration of 4 seconds. Results Esophageal injury as measured by percent transmurality was considerably higher at 50W and 10s duration than at 90W of power with 4s duration, although both settings showed potential for esophageal injury. The protective effect of the esophageal cooling device was evident for both cases, with a greater effect when using 50W for 10s (Figure 1). At the coldest device settings, using a 5 min pre-cooling period also reduced the transmurality of the intended atrial lesions. Esophageal protection in HPSD ablation Conclusions Esophageal cooling with a new patient temperature management device shows protective effects against thermal injury during RF ablation across a range of tissue thermal conductivity, using a variety of high-power settings, including 90W applied for 4 seconds. Adjusting the cooling power by adjusting the circulating water temperature in the device allows for a tailoring of the protective effects to operating conditions. Acknowledgement/Funding Attune Medical

6122Pulmonary vein isolation by different setting of high-power short-duration radiofrequency application: feasibility, short term efficacy and safety in patients with atrial fibrillation

Abstract Aims Pulmonary vein (PV) isolation (PVI) by point-by-point radiofrequency application (PPRF) results in longer procedures than cryoballoon ablation. In addition, it is associated with more esophageal lesions. The aim of this study was to evaluate the feasibility and safety of PVI by high power short duration (HPSD) PPRF in patients with atrial fibrillation. Methods PPRF around the PVs was done in 125 consecutive patients distributed in two chronologically successive groups. Conventional PPRF with 30W for ≤30 s under luminal esophageal temperature monitoring was performed in the first 47 patients (Group 1). 68 patients were enrolled in the HPSD (Group 2). Power was set to 50 W and delivered to reach a predefined lesion index value (LSI ≥5 or Abl-I ≥350) in the first 18 patients (Group 2A). 30 patients underwent PPRF with 60W for 7–10 s (Group 2B) and the last 30 patients underwent PPRF with 70W for 9 s (Group 2C). Esophageal endoscopy was performed after ablation in all patients. Results PVI of all targeted veins was achieved in 96% and 100% of patients of groups 1 and 2 respectively (p=0.6). Total RF time was 30 [27–43], 25 [20–29], 16 [14–20] and 14 [11–16] min in groups 1, 2A and 2B and 2C respectively (p&lt;0.001). RF was delivered for 12 [9–17] s vs 9 [8–9]s vs 9 [8–9] per application in groups 2 A, 2B and 2C respectively (p&lt;0.001). Total number of RFa to completely isolate all PV was 105 [90–126] in group 2A, 113 [90–135] in group 2B and 94 [79–112] in group 2C (p=0.12). First-pass PVI was achieved in 56%, 57% and 85% of left PV (p=0.038) and in 56%, 60% and 82% of right PV (p=0.13) in groups 50W, 60W and 70W respectively. The carina was the most frequent location of persistent conduction when first-pass failed. Reconnections occurred in 6%, 3% and 11% of left PV (p=0.6) and in 6%, 7% and 4% (p=0.63) of right PV in groups 50W, 60W and 70W respectively. Adenosine test was systematically used in groups 60W and 70W: the incidence of dormant conduction was 23% and 22% (p=0.9) in left PV and 20% and 22% (p=0.8) in right PV respectively. The incidence of esophageal lesions was 28% in Group 1, 2% in Group 2A, and 0% in groups 2B and 2C (p&lt;0.001). No other intraprocedural complications occurred in the high-power group. Total RF time Conclusions PVI is feasible with HPSD PPRF in most patients using shorter total RF times. This approach appears associated with very low incidence esophageal damage than the conventional one, especially when 60W/70W and shorter application time are used. Acknowledgement/Funding Grant of the Spanish Society of Cardiology

Safety and efficacy of delivering high-power short-duration radiofrequency ablation lesions utilizing a novel temperature sensing technology.

Delivery of high-power short-duration radiofrequency (RF) ablation lesions is not commonly used, in part because conventional thermocouple (TC) technology underestimates tissue temperature, increasing the risk of steam pop, and thrombus formation. We aimed to test whether utilization of an ablation catheter equipped with a highly accurate novel TC technology could facilitate safe and effective delivery of high-power RF lesions. Adult male Yorkshire swine were used for the study. High-power short-duration ablations (10-s total; 90 W for 4 s followed by 50 W for 6 s) were delivered using an irrigated force sensing catheter, equipped with six miniature TC sensors embedded in the tip electrode shell. Power modulation was automatically performed when the temperature reached 65°C. Ablation parameters were recorded and histopathological analysis was performed to assess lesion formation. One hundred and fourteen RF applications, delivered using the study ablation protocol in the ventricles of eight swine [53 in the right ventricle (RV), 61 in the left ventricle (LV)], were analysed. Average power delivered was 55.4 ± 5.3 W and none of the ablations resulted in a steam pop. Fourteen out of the 114 (12.3%) lesions were transmural. The mean lesion depth was 3.9 ± 1.1 mm for the 100 non-transmural lesions. Similar ablation parameters resulted in bigger impedance drop (11.6 Ω vs. 9.1 Ω, P = 0.009) and deeper lesions in the LV compared with the RV (4.3 ± 1.2 mm vs. 3.3 ± 0.8 mm, P < 0.001). Delivery of high-power short-duration RF energy applications, facilitated by a novel ablation catheter system equipped with advanced TC technology, is feasible, safe, and results in the formation of effective ablation lesions.

Thermal latency adds to lesion depth after application of high-power short-duration radiofrequency energy: Results of a computer-modeling study.

The use of ultra-short RF pulses could achieve greater lesion depth immediately after the application of the pulse due to thermal latency. A computer model of irrigated-catheter RF ablation was built to study the impact of thermal latency on the lesion depth. The results showed that the shorter the RF pulse duration (keeping energy constant), the greater the lesion depth during the cooling phase. For instance, after a 10-second pulse, lesion depth grew from 2.05mm at the end of the pulse to 2.39mm (17%), while after an ultra-short RF pulse of only 1 second the extra growth was 37% (from 2.22 to 3.05mm). Importantly, short applications resulted in deeper lesions than long applications (3.05mm vs. 2.39mm, for 1- and 10-second pulse, respectively). While shortening the pulse duration produced deeper lesions, the associated increase in applied voltage caused overheating in the tissue: temperatures around 100 °C were reached at a depth of 1mm in the case of 1- and 5-second pulses. However, since the lesion depth increased during the cooling period, lower values of applied voltage could be applied in short durations in order to obtain lesion depths similar to those in longer durations while avoiding overheating. The thermal latency phenomenon seems to be the cause of significantly greater lesion depth after short-duration high-power RF pulses. Balancing the applied total energy when the voltage and duration are changed is not the optimal strategy since short pulses can also cause overheating.