Dormant Conduction Research Articles

Safety and efficacy of very high-power short ablation in superior vena cava isolation in patients with atrial fibrillation

Abstract Backgrounds The superior vena cava (SVC) plays an important role in non-pulmonary vein (PV) foci to trigger atrial fibrillation (AF) and thus are occasionally isolated. A major complication in SVC isolation is phrenic nerve injury, and a shallower ablation depth might be less likely to cause complications. Recently, very high power short ablation (vHPSD) has been demonstrated to be effective in PV isolation. On the other hand, vHPSD has been reported to have shallower depth than the low-power ablation strategies, suggesting concerns about insufficient ablation in thicker myocardial sites. The vHPSD might be effective and safe in SVC isolation thinner than myocardium, however, the details were not elucidated. Purpose This study was aimed to examine the safety and efficacy of vHPSD strategy in SVC isolation, compared retrospectively with low power ablation strategies. Methods Patients with AF who were undergoing first-time SVC isolation were included. An activation map was performed from the SVC to the right atrium during sinus rhythm, and a circumferential isolation line was designed by the CARTO system at a height of 1.5cm above the earliest site. The site and extent of capture of the phrenic nerve by pacing on the circumferentially designed ablation line were recorded. The first step was to perform circumferential ablation except for the sites where the phrenic nerve was captured. If the SVC isolation was completed, the procedure was completed. If the isolation was inadequate, the sites of capture of the phrenic nerve were also ablated. Two groups of patients were analyzed: those performing vHPSD (n=27, vHPSD group) with a power of 90 watts for 3 seconds or those using lower-power (n=20, LP group) limited to 20-40 watts. Results Forty-seven patients who underwent the initial SVC isolation were evaluated. We analyzed all 351 points in the vHPSD group and all 364 points in the LP group with ablation of SVC. No differences were found in the distance of the SVC circumference on the isolation line (vHPSD: 71±10 vs. LPLD: 71±11mm, p=0.95) or the extent of phrenic nerve capture (12±7 vs. 12±9mm, p=0.82). All patients in the vHPSD group were successfully isolated first-pass; the first-pass isolation rate tended to be higher than in the LP group (100% vs. 85%, p=0.07). Differences were observed in temperature rise (49±4 vs. 28±4 degrees, p<0.001) and impedance drop (12±4 vs. 7±5Ω, p<0.001), although there were no differences in the contact force (15±8 vs. 15±7g, p= 0.73). The vHPSD group achieved SVC isolation with a shorter procedure time (9±4 vs. 17±5 min, p<0.001) and fewer ablation points (13±4 vs. 18±4, p<0.001) compared to the LP group. In the vHPSD cases, ATP was administered after isolation, but no dormant conduction was observed. Only in one case in the LP group, transient phrenic nerve injury was observed. Conclusion The vHPSD for SVC isolation might be safe and result in shorter procedure time and fewer ablation points.

Optimizing ablation sites in recurrent atrial fibrillation cases: a novel approach using emphasize settings

Abstract Backgrounds Although catheter ablation techniques for atrial fibrillation (AF) have advanced, a certain number of cases of re-conduction after pulmonary vein isolation (PVI) still exist and are the most common cause of recurrence of atrial tachyarrhythmias. In some cases, the diversity of anatomical wall thickness and fiber orientation around the PVs might contribute to re-conduction. Identification of optimal target ablation site of re-conduction could reduce unnecessary ablation and decrease the risk of complications. However, in cases where local electrograms consisted with far filed and near filed potentials were coexist, conventional activation mapping with bipolar electrograms sometimes fails to identify the re-conduction sites. Purpose We investigated the utility of using the Emphasize settings in the emphasis map obtained by combining activation mapping and peak frequency mapping in the EnSite X system to determine the optimal ablation sites compared to the conventional map based on the activation mapping. Methods Patients undergoing AF ablation of PVI with the EnSite X system who had recurrent cases or had PVI re-conduction at the initial ablation were included. We retrospectively analyzed the cases from January 2022 to November 2023. In all cases, bipolar voltage and activation maps for left atrium and PVs were obtained by a 16-pole grid catheter (Advisor HD Grid) during atrial pacing or sinus rhythm. Local activation timing and peak frequency maps of the left atrium were performed to obtain the Emphasize settings indicating the optimal ablation sites (E-group). The Emphasize settings obtained from the maps were adjusted to make the site of re-conduction most apparent (Figures). Another group determined the ablation sites based on the activation mapping (A-group). The clinical backgrounds, laboratory data, and echocardiography data were also evaluated. Intravenous administration of ATP was performed in all targeted PVs after successful re-isolation of PVs. Results Total 44 patients (69±10 years, 32 males) and 90 PVs were found to be re-conducted and analyzed. The gaps of 34 and 40 points of PVI were observed in the E-group and C-group, respectively. The number of needs for the ablation points to successful elimination of gap was markedly smaller in the E-group (1.3±0.7 vs. 6.2±3.2, p<0.001). The optimal Emphasize settings was 340 ±75 Hz in the E-group. None of the cases showed dormant conductions by ATP administration in both groups. There were no differences in age, gender, left atrial volume index, left ventricular ejection fraction, serum creatinine levels, and N-terminal pro-brain natriuretic peptide levels between the two groups. Conclusion The optimal ablation site was visualized by adjusting the Emphasize settings, and the number of ablation points to re-isolation of PV might be markedly reduced.

Characterization of conduction recovery and atrial electrophysiological properties after pulmonary vein isolation using pulsed field ablation

Abstract Background Pulsed field ablation (PFA) is a relatively new technology for isolation of pulmonary veins in patients with atrial fibrillation (AF). Data addressing reasons for recurrent atrial fibrillation despite primarily successful pulmonary vein isolation (PVI) using PFA are scarce, due to an up to date limited number of patients treated this way. Objective The aim of this study was to analyze electrophysiological characteristics of reconduction and / or left atrial substrate of patients referred to our center for Re-Do procedures for recurrent AF after an initial PVI using PFA. Methods 90 patients (mean age 66±9 years, 69 male (77%)) had been treated in our center from November 2021 to July 2023 with PVI using PFA. 9 (10%) of these patients were referred for Re-Do procedures. These were performed by radiofrequency ablation (RFA) using Carto system including high density mapping and high power / short duration (HPSD) ablation. We analyzed location of PV reconnection and low voltage areas (LVA) in the left atria. Results 7 out of 9 patients (77%) presented with reconnections of pulmonary veins. In one patient a single vein showed reconduction (RSPV), in 5 patients 2 veins were conducting (1x LSPV, 3x LIPV, 1 left sided common os (LCo), 1x RSPV, 3x RIPV). None of the patients showed 3 or 4 reconnected veins. Areas of reconduction in each vein were: LSPV 1x ridge, 1x posterior; LIPV 1x posterior, 1x anterior and posterior; LCo 1x posterior, RSPV 1x anterior, 2x carina, 1x anterior and posterior; RIPV 1x complete, 2x carina. In 7 patients a fibrotic atrial cardiomyopathy (FACM) was diagnosed via high density mapping of LVA’s. In 2 of these patients all 4 pulmonary veins were chronically isolated after the initial PVI. All patients except one (very small anterior LVA) with FACM ≥1 were treated with additional linear or encircling lesions according to the individual extent of the fibrotic areas. 2 patients had no LVA’s detectable. In one of those 2 patients 2 veins had reconnected. The other patient had chronically isolated veins (no proof of dormant conduction with adenosine) and no detectable non-PV-triggers under isoprenaline. Conclusion In the population of patients undergoing PVI using PFA in our center, only 10% had clinically relevant recurrences leading to the necessity of a Re-Do procedure. Most patients (77%) in this setting had reconnections of pulmonary veins. There is a tendency of posterior reconnections of the left pulmonary veins and reconnections of the carina of the right pulmonary veins, but the number of patients is too small to clearly define predilection sites that have to be paid attention to when using PFA. Additionally, left atrial substrate is an important problem in patients with recurrent AF despite primarily successful PVI and has to be considered and thoroughly addressed in Re-Do procedures.Reconnection of LSPV and anterior LVAAblation of RSPV and LSPV (posterior)

Where is the gap after a 90 W/4 s very-high-power short-duration ablation of atrial fibrillation?: Association with the left atrial-pulmonary vein voltage and wall thickness.

Although pulmonary vein isolation (PVI) for atrial fibrillation (AF) utilizing radiofrequency (RF) applications with a very high-power and short-duration (vHPSD) has shortened the procedure time, the determinants of pulmonary vein (PV) gaps in the first-pass PVI and acute PV reconnections are unclear. An extensive encircling PVI was performed with the QDOT MICRO catheter with a vHPSD (90 W-4 s) in 30 patients with AF (19 men, 64 ± 10 years). The association of the PV gap sites (first-pass PVI failure, acute PV reconnections [spontaneous reconnections or dormant conduction provoked by adenosine triphosphate] or both) with the left atrial (LA) wall thickness and LA bipolar voltage on the PVI line and ablation-related parameters were assessed. PV gaps were observed in 29 (6%) of 480 segments (16 segments per patient) in 17 patients (56%). The PV gaps were associated with the LA wall thickness, bipolar voltage, and the number of RF points (LA wall thickness, 2.5 ± 0.5 vs. 1.9 ± 0.4 mm, p < .001; bipolar voltage, 2.59 ± 1.62 vs. 1.34 ± 1.14 mV, p < .001; RF points, 6 ± 2 vs. 4 ± 2, p = .008) but were not with the other ablation-related parameters. Receiver operating characteristic curves yielded that an LA wall thickness ≥2.3 mm and bipolar voltage ≥2.40 mV were determinants of PV gaps with an area under the curve of 0.82 and 0.73, respectively. The LA voltage and wall thickness on the PV-encircling ablation line were highly associated with PV gaps using the 90 W/4 s-vHPSD ablation.

Focal Pulsed Field Ablation for Atrial Arrhythmias: Efficacy and Safety under Deep Sedation.

Focal pulsed field ablation (PFA) is a novel technique for treating cardiac arrhythmias. It has demonstrated positive results in initial studies and has a good safety profile. In recent studies, PFA was often utilized for first-time pulmonary vein isolation (PVI) and was performed under general anesthesia. In our study, we assessed the feasibility, safety, acute procedural efficacy, and efficiency of focal PFA under deep sedation in patients, 80% of whom had undergone at least one left atrial ablation previously. We treated 30 patients (71 ± 7, 46% male) using the CENTAURI system for various atrial arrhythmias, including atrial fibrillation, typical and atypical atrial flutter, and focal atrial tachycardia. The average procedure and fluoroscopy times were 122 ± 43 min and 9 ± 7 min, respectively. A total of 83.33% of patients received additional line ablations beyond PVI, specifically targeting the posterior box and anterior mitral line. All ablations were successfully performed in deep sedation with only one major and one minor complication observed. The major complication was a vasospasm of the right coronary artery during ablation of the cavotricuspid isthmus, which was treated successfully with intracoronary nitroglycerin. All patients could be discharged in sinus rhythm. Moreover, adenosine appears effective in identifying dormant conduction in some patients after focal PFA. In conclusion, focal PFA is an effective approach for complex left atrial ablations under deep sedation, offering both high efficacy and efficiency with a reliable safety profile. Studies on long-term outcomes are needed.

Validation Strategy for Pulmonary Vein Isolation in Patients With Paroxysmal Atrial Fibrillation in Long-Term Maintaining Sinus Rhythm: A Randomized Controlled Study.

Background: Data comparing the outcomes of loose versus rigorous validation strategies for pulmonary vein isolation (PVI) in patients with paroxysmal atrial fibrillation (PAF) are limited. We aimed to prospectively assess the effectiveness of loose versus rigorous validation for PVI in patients with PAF with a maintained sinus rhythm. Methods: Patients (n = 117) with PAF were randomized to receive either loose validation (n = 59) or rigorous validation (n = 58) after PVI. The presence of dormant conduction in loose validation was assessed only by adenosine administration followed by isoproterenol infusion. The complete absence of pulmonary vein (PV) potentials in rigorous validation was confirmed by the combination of the Lasso catheter with isoproterenol plus adenosine. Dormant conduction, revealed by validation after PVI, was ablated until all reconnections were eliminated. Results: The procedure time in the rigorous validation group was greater than that in the loose validation group (161.3 ± 52.7 min vs. 142.5 ± 37.6 min, p=0.03, respectively). After successful PVI, the detection of dormant PV reconnections in the rigorous validation group was significantly greater than that in the loose validation group (69.0% vs. 37.3%, p=0.001). However, after reisolation of the sites of dormant PV conduction, the postablation recurrence rates in 1.3 years were similar between the groups (79.2% vs. 83.6%, p=0.67). Conclusion: Rigorous validation can reveal dormant conduction in more than two-thirds of patients with PAF undergoing PVI. However, rigorous validation and additional ablation of the resulting connections do not improve long-term outcomes when a protocol that includes electrophysiological confirmation and pharmacological validation is used.

PO-01-042 OUTCOMES IN ATRIAL FIBRILLATION USING ADENOSINE TO CHECK FOR DORMANT CONNECTIONS DURING CATHETER ABLATION

Adenosine is used to uncover dormant connections after pulmonary vein isolation (PVI) for atrial fibrillation (AF). There are conflicting reports in the literature on whether this technique reduces AF recurrence. To determine if adenosine provocation (APROV) to check for dormant conduction following PVI reduces AF recurrence. AF ablation procedures performed at a single center from 2013 to 2021 were analyzed. The endpoint was AF recurrence after a 3-month blanking period. AF recurrence was defined as AF lasting for more than 30 seconds. 1:1 propensity score match (PSM) was performed with covariates that have been shown to predict AF recurrence in previous studies (gender, age, BMI, AF classification, obstructive sleep apnea (OSA), hypertension (HTN), and diabetes mellitus (DM). The minimum duration of follow-up was 6 months. Adenosine was used at the procedure physician’s discretion with a minimum dose of 12 mg. Dormant connections were ablated, and persistent PVI with elimination of dormant conduction with adenosine re-challenge was confirmed in all cases. Kaplan-Meier analysis was conducted to assess time to AF recurrence in the entire cohort and the PSM cohort. We analyzed 1544 AF ablations (1111 de novo, 428 repeat ablation) at a single academic medical center. Adenosine was used in 64% of cases. The study population was 65.5% male with a mean age 66 years. Patient co-morbidities included DM (17%), HTN (55%), and OSA (18%). There was no significant difference in time to AF recurrence in the entire cohort with APROV (HR 0.95, CI 0.78-1.16, p=0.6). After PSM, there were 450 patients in each group with AF ablations with 72% paroxysmal AF and 28% persistent AF. There was no difference in time to AF recurrence in the PSM cohort with APROV (HR 0.94, CI 0.75-1.18, p=0.6, Figure 1), with no differences observed between de novo vs repeat ablations. Adenosine provocation is not associated with decreased AF recurrence.

Early dose of Adenosine, postRadiofrequency abLation of accessory pathwaYin determining acute procedural success (EARLY study).

Post ablation of the accessory pathway (AP), the patient is observed in the catheterization laboratory for a variable period for resumption of pathway conduction. Aim of the study was to determine whether the administration of intravenous adenosine at 10 min after ablation of APwould have the same diagnostic accuracy as waiting for 30 min in predicting the resumption of AP conduction. This was a prospective interventional study conducted in two centers. Post ablation of the AP, intravenous adenosine was administered at 10 min to look for dormant pathway conduction. The response was recorded as positive (presence of pathway conduction), negative (absence), or indeterminate (not able to demonstrate AV and VA block and inability to ascertain AP conduction). The study included 110 procedures performed in 109 patients. Adenosine administration at 10 min showed positive result in 3 cases (2.7%), negative result in 99 cases (90%) and indeterminate result in 8 cases (7.3%). Reconnection of accessory pathway at 30 min postablation was seen in 8 cases (7.3%). Of these 8 cases, 10 minadenosine administration showed positive test in 3 patients and negative test in 5 patients. Adenosine test at 10 min has a sensitivity, specificity, positive predictive value, and negative predictive value of 37.5%, 100%, 100%, and 94.9% in identifying the recurrence of accessory pathway conduction at 30 min, respectively. Absence of pathway conduction on administration of adenosine 10 min postablation does not help predict the absence of resumption of conduction thereafter.

Clinical Significance of Adenosine-Induced Atrial Fibrillation after Complete Pulmonary Vein Isolation.

Background: Adenosine can cause dormant electrical conduction between the pulmonary vein and left atrium after pulmonary vein isolation (PVI). Adenosine can also induce atrial fibrillation (AF) during catheter ablation. However, the clinical outcomes and effects of additional ablation for the trigger sites of adenosine-induced AF (AIAF) are unknown. This study therefore aimed to evaluate the clinical significance of AIAF. Methods: Between January 2010 and September 2019, we analyzed 616 consecutive patients with paroxysmal AF (PAF) who underwent radiofrequency catheter ablation (RFCA), including wide-area circumferential pulmonary vein isolation (PVI) and post-PVI adenosine testing. Results: Among 616 patients, 134 (21.7%) and 34 (5.5%) showed dormant conduction and AIAF, respectively. Eight patients (1.3%) had both dormant conduction and AIAF. The AF recurrence rate was not significantly different between patients with and without AIAF (16.7% vs. 18.6%, log-rank p = 0.827) during a mean follow-up period of 17.9 ± 18 months. Additional RFCA for the trigger site was attempted in 10 patients with AIAF; however, the recurrence rate of atrial arrhythmias was also not different between the groups with and without additional ablation (20% vs. 16.7%, log-rank p = 0.704). Conclusions: AIAF after PVI was not clinically associated with recurrence during long-term follow-up. Ablation of the trigger site in AIAF did not improve the clinical outcomes.

Long-term outcome of adenosine-induced atrial fibrillation after atrial fibrillation ablation: A propensity score matching analysis.

Nonpulmonary vein (non-PV) foci, in addition to pulmonary vein (PV), are considered important in initiating atrial fibrillation (AF). This study investigates the adenosine triphosphate (ATP) as a method for inducing non-PV ectopy. The study cohort consisted of 1388 patients with AF (728 with paroxysmal AF, 650 with nonparoxysmal AF) who underwent catheter ablation. To confirm dormant PV conductions and non-PV foci, 20 or 40mg ATP was administered intravenously at the end of the procedure. The ATP test induced AF in 36 of 1388 (2.6%) patients, in whom two (6%) had ectopy arising from the both atria, 15 (42%) from the right atrium (RA), and five (14%) from left atrium (LA). Because of a lack of reproducibility, the accurate location of non-PV foci was unidentified in the remaining 11 (31%) patients. Additional radiofrequency ablation to non-PV foci induced ATP administration was not performed in 34 patients. Among all 1388 patients, 64 were assigned to the ATP-AF(+) and ATP-AF(-) groups using a propensity score matching analysis (32 patients in each group). During the follow-up period, recurrent AF was observed in 9 of 32 (28%) patients in the ATP-AF(+) group and in 10 of 32 (31%) patients in the ATP-AF(-) group (log-rank p=.84, hazard ratio 0.91 [95% confidence interval 0.36-2.27]). In the univariate analysis, AF induction by ATP test was not predictive of AF recurrence (p=.78). ATP-induced AF was not associated with AF recurrence in the distant period.

Temperature-controlled high-power short-duration ablation with 90W for 4s: outcome, safety, biophysical characteristics and cranial MRI findings in patients undergoing pulmonary vein isolation.

High-power short-duration (HPSD) radiofrequency ablation (RFA) is highly efficient and safe while reducing procedure and RF time in pulmonary vein isolation (PVI). The QDot™ catheter is a novel contact force ablation catheter that allows automated flow and power adjustments depending on the local tissue temperature to maintain a target temperature during 90W/4s lesions. We analysed intraprocedural data and periprocedural safety using the QDot-catheter in patients undergoing PVI for paroxysmal atrial fibrillation (PAF). We included n = 48 patients undergoing PVI with the QDot-catheter with a temperature-controlled HPSD ablation mode with 90W/4s (TC-HPSD). If focal reconnection occurred besides repeat ablation, the ablation mode was changed to 50W/15s (QMode). N = 23 patients underwent cerebral MRI to detect silent cerebral lesions. Mean RF time was 8.1 ± 2.8min, and procedure duration was 84.5 ± 30min. The overall maximal measured catheter tip temperature was 52.0°C ± 4.6°C, mean overall applied current was 871mA ± 44mA and overall applied energy was 316J ± 47J. The mean local impedance drop was 12.1 ± 2.4 Ohms. During adenosine challenge, n = 14 (29%) patients showed dormant conduction. A total of n = 24 steam pops were detected in n = 18 patients (39.1%), while no pericardial tamponade occurred. No periprocedural thromboembolic complications occurred, while n = 4 patients (17.4%) showed silent cerebral lesion. TC-HPSD ablation with 90W/4s using the QDot-catheter led to a reduction of procedure and RF time, while no major complications occurred. Despite optimized temperature control and power adjustment, steam pops occurred in a rather high number of patients, while none of them leads to tamponade or to clinical or neurological deficits.

PO-710-04 CONTEMPORARY PREVALENCE AND PREDICTORS OF INTACT PULMONARY VEIN ISOLATION IN PATIENTS UNDERGOING REPEAT ATRIAL FIBRILLATION ABLATION

Pulmonary vein isolation (PVI) is the primary goal of atrial fibrillation (AF) ablation. Prior studies have noted a 50-95% prevalence of pulmonary vein (PV) reconnection at the time of repeat ablation. However, the prevalence of PV reconnection with contemporary AF ablation techniques, including high frequency jet ventilation, is unknown. Furthermore, there is an incomplete understanding of predictors of intact PVI at the time of repeat ablation. To assess the prevalence of PV reconnection in a contemporary cohort utilizing jet ventilation, contact force catheters, and adenosine testing for dormant conduction, and identify patient characteristics and ablation techniques that predict PVI at time of repeat ablation. We reviewed 615 consecutive radiofrequency AF ablations from 2013-2019 at an academic medical center performed by a single operator. There were 121 unique patients who underwent a de novo AF ablation followed by a repeat AF ablation. We evaluated clinical and previous procedural characteristics to identify predictors of PVI at the time of repeat ablation, using logistic regression models. Of the 121 patients, 42.1% were female, average age was 64.5 years, and BMI 31. At the time of repeat ablation, 57% (n=69) had intact prior PVI. Baseline characteristics of patients with intact PVI and reconnected PVI were similar, including age (64 years and 65 years; p=0.75), left atrial diameter (4.13 cm and 4.39 cm; p=0.09), left ventricular ejection fraction (54.5 % and 55.4%; p = 0.38), and time to first atrial fibrillation recurrence (237 days v. 344 days, p=0.28). The only significant clinical predictor of intact PVI was the pre-procedure diagnosis of atypical atrial flutter (20.3 % v. 3.8%, p=0.02) (Figure 1). In multivariate analysis, prior mitral line ablation (OR 8.93, 95%CI [3.65, 21.87]: p <0.01) and first pass isolation of right pulmonary vein during the index AF ablation (OR 2.59, 95% CI [1.09, 6.12]: p = 0.03) strongly predicted intact PVI at the time of repeat AF ablation. With contemporary techniques, PVI reconnection is seen in 43% of patients at the time of repeat AF ablation. History of atypical flutter, prior mitral line ablation, and first pass isolation of the right PVs were significant predictors for intact PVI.

The target ablation index values for electrical isolation of the superior vena cava.

The ablation index (AI), developed as a radiofrequency (RF) catheter ablation composite component endpoint, which incorporates contact force (CF), time, and power in a weighted formula, has been reported to be useful for a durable pulmonary vein isolation (PVI) to treat atrial fibrillation (AF). No study has reported the target AI value for the SVC isolation (SVCI). In this study, we aimed to investigate the target AI for the SVCI. Thirty-six AF patients who underwent an initial SVCI were enrolled. Ablation was performed at 556 points. The sites where dormant conduction was induced or additional ablation was needed were defined as touch up sites (n = 36). We compared the energy deliver time, power, generator impedance (GI) drop, local bipolar voltage, contact force (CF), force-time integral (FTI), and AI between the touch up sites and the no touch up sites (n = 520). The FTI and AI were significantly lower at the touch up sites (touch up sites vs. no touch up sites; FTI, 126.5 [99.3-208.8] vs. 244 [184-340.8], p < 0.0001; AI, 350.1 ± 43.6 vs. 277.2 ± 21.8, p < 0.0001). The median value of the AI at the no touch up sites was 350, and no reconnections were seen where the minimum AI value was more than 308. Most of the touch up sites were located in the anterior wall and lateral wall (anterior wall, 20/36 sites [55.6%]; lateral wall, 10/36 sites [27.8%]; septal wall, 6/36 sites [16.7%]; posterior wall, 0/36sites [0.0%]). The target AI value for the SVCI should be 350, and at least 308 would be needed.

Procedural characteristics of pulmonary vein isolation with high-power short-duration setting compared to conventional setting

PurposeThe purpose of this study was to investigate the safety and efficacy of high-power short-duration (HP-SD) ablation compared to conventional ablation in patients with atrial fibrillation (AF).MethodsWe enrolled consecutive 158 drug-refractory symptomatic AF patients (119 males, mean age 63 ± 10 years) who had undergone first radiofrequency pulmonary vein isolation (PVI). PVI was performed using the conventional setting (20–35 W) in 73 patients (Conventional group) and using the HP-SD setting (45–50 W) in 85 patients (HP-SD group). The rate of first pass isolation, remaining gaps after circumferential ablation, dormant conduction, and the radiofrequency application time in each pulmonary vein (PV) were compared between the groups.ResultsThe first pass isolation ratio was significantly higher in the HP-SD group than in the Conventional group (81% vs. 65%, P = 0.027) in the right PV, but did not differ in the left PV. The remaining gaps were fewer in the right superior PV (4% vs. 21%, P = 0.001) and left inferior PV (1% vs. 8%, P = 0.032) areas, and the radiofrequency application time in each PV was shorter (right PV, 12.0 ± 8.9 min vs. 34.0 ± 31.7 min, P < 0.001; left PV, 10.6 ± 3.6 min vs. 25.7 ± 22.3 min, P < 0.001) in the HP-SD group than in the Conventional group.ConclusionThe use of the HP-SD setting might contribute to improve the first pass isolation rate and to shorten the radiofrequency application time in each PV.

Abstract 10794: Adenosine Induced Dormant Pulmonary Vein Reconnection Predicts Recurrent Atrial Fibrillation After Pulmonary Vein Isolation: Systematic Review and Meta-Analysis

Introduction: Adenosine can be used to reveal dormant pulmonary vein (PV) conduction following pulmonary vein isolation (PVI) for the treatment of atrial fibrillation (AF). Hypothesis: We performed a systematic review and meta-analysis to assess the impact of adenosine administration in patients undergoing PVI for AF. Methods: We searched PubMed, Medline, Embase, Ovid, and Cochrane for studies that reported freedom from AF during follow-up compared between those without reconnection and those with reconnection (requiring further targeted ablation). Statistical analysis was performed using meta-package for R version 4.0 and Rstudio version 1.2. Results: A total of 20 eligible studies (14 prospective, 3 retrospective, 3 randomized) consisting of 3,595 patients (Reconnection group - 1,228 and No Reconnection group - 2,367) were included in the meta-analysis. The follow-up period ranged from 6.1 months to 36 months. The freedom from AF in patients with PV reconnection was 62.45% compared to 68.10% of patients without PV reconnection. There was significant heterogeneity between studies (I2 = 68%; p &lt; 0.001). Random-effects meta-analysis showed significantly higher freedom from AF in patients with no identified reconnection than those with identified reconnection (RR 0.89; 95% CI 0.80 - 0.99; p = 0.03). Conclusions: Adenosine-guided dormant conduction was associated with higher AF recurrence despite further ablation, but there was substantial heterogeneity between trials. Future research should be directed to improved techniques, and optimal methodology, including adenosine dosage and wait time between PVI and adenosine administration.

Absence of first-pass isolation is associated with poor pulmonary vein isolation durability and atrial fibrillation ablation outcomes.

BackgroundPulmonary vein (PV) reconnection is the main cause of atrial fibrillation (AF) recurrence. This study aimed to examine the effect of first‐pass PV isolation (PVI) on PV reconnection frequency during the procedure and on AF ablation outcomes.MethodsThis retrospective study included 446 patients with drug‐refractory AF (370 men, aged 64 ± 10 years) who underwent initial PVI using an open‐irrigated contact force catheter between January 2015 and October 2016. We investigated the effect of first‐pass PVI on PV reconnection during spontaneous PV reconnection and dormant conduction after an adenosine triphosphate challenge.ResultsFirst‐pass PVI was achieved in 69% (617/892) of ipsilateral PVs, of which we observed PV reconnection during the procedure in 134 (22%) PVs. This value was significantly lower than that observed in those without first‐pass PVI (50%, 138/275) (P < .0001). We divided the subjects into two groups based on the presence or absence of first‐pass PVI in at least one of two ipsilateral PVs: first‐pass (n = 383, 86%) and non‐first‐pass groups (n = 63, 14%). The 2‐year AF recurrence‐free rate was significantly higher in the first‐pass group than in the other group (75% vs 59%, log‐rank P = .032). In 78 patients with repeat AF ablation, the PV reconnection rate in the second procedure was significantly lower in PVs that had first‐pass isolation in the first procedure (34% vs 73%, P < .0001).ConclusionsAbsence of first‐pass PVI was associated with a higher frequency of spontaneous PV reconnection and dormant conduction and poor ablation outcomes. First‐pass isolation may be a useful marker for better PVI durability.

Optimized lesion size index (o-LSI): A novel predictor for sufficient ablation of pulmonary vein isolation.

BackgroundAlthough the lesion size index (LSI) has been well established, it is sometimes difficult to achieve first‐pass pulmonary vein isolation (PVI) and to avoid acute pulmonary vein reconnections, even with LSI‐guided procedures. The purpose of this study was to assess the predictive accuracy of a novel parameter, the optimized lesion size index (o‐LSI), to perform PVI.MethodsThe voltage maps created by the Advisor™ high‐density (HD) grid catheter before PVI in 35 atrial fibrillation (AF) patients were examined for an association between the voltage amplitude and insufficient ablation sites (IAS), which were defined as either (i) spontaneous reconnection sites, (ii) dormant PV conduction sites unmasked with 20 mg of adenosine triphosphate disodium hydrate (ATP) injection, or (iii) PV‐LA gap sites after the initial PVI.ResultsIAS was observed in 25/1417 of the total ablation sites. IAS was significantly associated with higher bipolar voltage areas (4.20 ± 2.68 vs 2.43 ± 1.93 mV, P < .0001) but not with LSI. A novel index, o‐LSI (defined as LSI/bipolar voltage), was significantly lower in IAS than in others (1.14 [0.82, 1.81] vs 2.35 [1.31, 4.80] LSI/mV). By receiver operating characteristic analysis, an o‐LSI of 2.04 was the best cutoff value for the prediction of IAS (88% sensitivity and 55% specificity, P < .0001, areas under the curve: 0.742).ConclusionLow o‐LSI was strongly associated with IAS, potentially providing a novel index to improve first‐pass PV isolation.

Superior vena cava isolation using a novel ablation catheter incorporating local impedance monitoring.

A novel technology able to measure the local impedance (LI) during radiofrequency ablation has become available for clinical use. We investigated the change in the LI characteristics during superior vena cava isolations (SVCIs) using a novel catheter equipped with mini-electrodes. Twenty paroxysmal atrial fibrillation patients (68 ± 9 years; 14 males) underwent an SVCI by targeting breakthroughs. Subsequently, dormant conduction provoked by adenosine triphosphate (ATP) was evaluated. Electrical SVCIs were successfully achieved in all with 7.2 ± 3.0 radiofrequency applications (RFA) without any complications. The procedure and fluoroscopic times were 13.1 ± 8.1 and 2.8 ± 2.3 min. No ablation was required at the anteroseptal SVC in 19 (95.0%) patients. The baseline LI and generator impedance (GI) were 125 ± 23 and 105 ± 14Ω. LI drops during RFA were significantly greater than GI drops (17 ± 12 vs. 4 ± 4Ω, p < 0.001). The correlation between the LI drops and GI drops was relatively high (R = 0.69, p < 0.001). LI drops were highest at the septal SVC and lowest at the lateral followed by antero-lateral SVC. The baseline electrogram amplitude between the mini-electrodes and tip-ring electrodes was 1.2 ± 1.4 and 0.8 ± 0.6 mV. The mini-electrode amplitude is more sharply attenuated with a greater magnitude than the tip-ring amplitude (p < 0.001). ATP-provoked dormant conduction was exposed in 10/17 (58.8%) patients and antero-lateral SVC gap locations in 7. Antero-lateral SVC LI drops were similar between patients with and without dormancy. The LI drop magnitude during RFA significantly differed among the SVC segments. Antero-lateral SVC ATP-provoked dormant conduction was often exposed, and additional applications are recommended following the isolation for a robust SVCI.

Pulmonary Vein Stenosis After Atrial Fibrillation Ablation: Insights From the ADVICE Trial

BackgroundPulmonary vein (PV) stenosis is a complication of atrial fibrillation (AF) ablation. The incidence of PV stenosis after routine post-ablation imaging remains unclear and is limited to single-centre studies. Our objective was to determine the incidence and predictors of PV stenosis following circumferential radiofrequency ablation in the multicentre Adenosine Following Pulmonary Vein Isolation to Target Dormant Conduction Elimination (ADVICE) trial. MethodsPatients with symptomatic AF underwent circumferential radiofrequency ablation in one of 13 trial centres. Computed tomographic (CTA) or magnetic resonance (MRA) angiography was performed before ablation and 90 days after ablation. Two blinded reviewers measured PV diameters and areas. PVs with stenosis were classified as severe (> 70%), moderate (50%-70%), or mild (< 50%). Predictors of PV stenosis were identified by means of multivariable logistic regression. ResultsA total of 197 patients (median age 59.5 years, 29.4% women) were included in this substudy. PV stenosis was identified in 41 patients (20.8%) and 47 (8.2%) of 573 ablated PVs. PV stenosis was classified as mild in 42 PVs (7.3%) and moderate in 5 PVs (0.9%). No PVs had severe stenosis. Both cross-sectional area and diameter yielded similar classifications for severity of PV stenosis. Diabetes was associated with a statistically significant increased risk of PV stenosis (OR 4.91, 95% CI 1.45-16.66). ConclusionsIn the first systematic multicentre evaluation of post-ablation PV stenosis, no patient acquired severe PV stenosis. Although the results are encouraging for the safety of AF ablation, 20.8% of patients had mild or moderate PV stenosis, in which the long-term effects are unknown.

Pulmonary Vein Isolation With Single Pulse Irreversible Electroporation: A First in Human Study in 10 Patients With Atrial Fibrillation.

Irreversible electroporation (IRE) is a promising new nonthermal ablation technology for pulmonary vein (PV) isolation in patients with atrial fibrillation. Experimental data suggest that IRE ablation produces large enough lesions without the risk of PV stenosis, artery, nerve, or esophageal damage. This study aimed to investigate the feasibility and safety of single pulse IRE PV isolation in patients with atrial fibrillation. Ten patients with symptomatic paroxysmal or persistent atrial fibrillation underwent single pulse IRE PV isolation under general anesthesia. Three-dimensional reconstruction and electroanatomical voltage mapping (EnSite Precision, Abbott) of left atrium and PVs were performed using a conventional circular mapping catheter. PV isolation was performed by delivering nonarcing, nonbarotraumatic 6 ms, 200 J direct current IRE applications via a custom nondeflectable 14-polar circular IRE ablation catheter with a variable hoop diameter (16-27 mm). A deflectable sheath (Agilis, Abbott) was used to maneuver the ablation catheter. A minimum of 2 IRE applications with slightly different catheter positions were delivered per vein to achieve circular tissue contact, even if PV potentials were abolished after the first application. Bidirectional PV isolation was confirmed with the circular mapping catheter and a post ablation voltage map. After a 30-minute waiting period, adenosine testing (30 mg) was used to reveal dormant PV conduction. All 40 PVs could be successfully isolated with a mean of 2.4±0.4 IRE applications per PV. Mean delivered peak voltage and peak current were 2154±59 V and 33.9±1.6 A, respectively. No PV reconnections occurred during the waiting period and adenosine testing. No periprocedural complications were observed. In the 10 patients of this first-in-human study, acute bidirectional electrical PV isolation could be achieved safely by single pulse IRE ablation.