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We compared the efficacy and complication rates of quantitative radiofrequency ablation guided by ablation index (RFCA-AI) with those of second-generation cryoballoon ablation (CBA-2). Consecutive patients (n = 230) with symptomatic atrial fibrillation (AF) undergoing a first ablation CBA-2 (92 patients) or RFCA-AI (138 patients) procedure were enrolled in this study. The late recurrence rate in the CBA-2 group was higher than that in the RFCA-AI group (P =.012). Subgroup analysis showed the same result in patients with paroxysmal AF (PAF) (P =.039), but no difference was found in patients with persistent AF (P =.21). The average operation duration in the CBA-2 group (85 [75-99.5] minutes) was shorter than that in the RFCA-AI group (100 [84.5-120] minutes) (P <.0001), but the average exposure time (17.36(13.87-22.49) vs 5.49(4.00-8.24) minutes) in the CBA-2 group and X-ray dose (223.25(149.15-336.95) vs 109.15(80.75-168.7) mGym) were significantly longer than those in RFCA-AI group (P <.0001). Multivariate logistic regression analysis showed that left atrial diameter (LAD), early recurrence, and methods of ablation (cryoballoon ablation) were independent risk factors for late recurrence after AF ablation. Early recurrence of AF and LAD were independent risk factors for predicting late recurrence after AF ablation. [ABSTRACT FROM AUTHOR]

Introduction: The utility of ablation index (AI) to guide ventricular tachycardia (VT) ablation in patients with structural heart disease is unknown. The aim of this study was to assess procedural characteristics and clinical outcomes achieved using AI‐guided strategy (target value 550) or conventional non‐AI‐guided parameters in patients undergoing scar‐related VT ablation. Methods: Consecutive patients (n = 103) undergoing initial VT ablation at a single center from 2017 to 2022 were evaluated. Patient groups were 1:1 propensity‐matched for baseline characteristics. Single lesion characteristics for all 4707 lesions in the matched cohort (n = 74) were analyzed. The impact of ablation characteristics was assessed by linear regression and clinical outcomes were evaluated by Cox proportional hazard model. Results: After propensity‐matching, baseline characteristics were well‐balanced between AI (n = 37) and non‐AI (n = 37) groups. Lesion sets were similar (scar homogenization [41% vs. 27%; p =.34], scar dechanneling [19% vs. 8%; p =.18], core isolation [5% vs. 11%; p =.4], linear and elimination late potentials/local abnormal ventricular activities [35% vs. 44%; p =.48], epicardial mapping/ablation [11% vs. 14%; p =.73]). AI‐guided strategy had 21% lower procedure duration (−47.27 min, 95% confidence interval [CI] [−81.613, −12.928]; p =.008), 49% lower radiofrequency time per lesion (−13.707 s, 95% CI [−17.86, −9.555]; p <.001), 21% lower volume of fluid administered (1664 cc [1127, 2209] vs. 2126 cc [1750, 2593]; p =.005). Total radiofrequency duration (−339 s [−24%], 95%CI [−776, 62]; p =.09) and steam pops (−155.6%, 95% CI [19.8%, −330.9%]; p =.08) were nonsignificantly lower in the AI group. Acute procedural success (95% vs. 89%; p =.7) and VT recurrence (0.97, 95% CI [0.42–2.2]; p =.93) were similar for both groups. Lesion analysis (n = 4707) demonstrated a plateau in the magnitude of impedance drops once reaching an AI of 550–600. Conclusion: In this pilot study, an AI‐guided ablation strategy for scar‐related VT resulted in shorter procedure time and average radiofrequency time per lesion with similar acute procedural and intermediate‐term clinical outcomes to a non‐AI‐guided approach utilizing traditional ablation parameters. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Introduction: Although left atrial wall thickness (LAWT) is known to be varied, a fixed target Ablation Index (AI) based pulmonary vein isolation (PVI) has been suggested in catheter ablation for atrial fibrillation (AF). We aimed to evaluate the efficacy and safety of PVI applying tailored AI based on LAWT assessed by cardiac computed tomography (CT). Methods: The thick segment was defined as the segment including ≥LAWT grade 3 (≥1.5 mm). The fixed AI strategy was defined as AI targets were 450 on the anterior/roof segments and 350 on the posterior/inferior/carina segments regardless of LAWT. The tailored AI strategy consisted of AI increasing the targets to 500 on the anterior/roof segments and to 400 on the posterior/inferior/carina segments when ablating the thick segment. After PVI, acute pulmonary vein (PV) reconnection, defined by the composite of residual potential and early reconnection, was evaluated. Results: A total of 156 patients (paroxysmal AF 72%) were consecutively included (86 for the fixed AI group and 70 for the tailored AI group). The tailored AI group showed a significantly lower rate of segments with acute PV reconnection than the fixed AI group (8% vs. 5%, p =.007). The tailored AI group showed a trend for shorter ablation time for PVI. One‐year AF/atrial tachycardia free survival rate was similar in two groups (87.2% in the fixed AI group and 90.0% in the tailored AI group, p =.606). Conclusion: Applying tailored AI based on the LAWT was a feasible and effective strategy to reduce acute PV reconnection after PVI. [ABSTRACT FROM AUTHOR]

Introduction: To investigate the optimal range of quantitative ablation index (AI) value during superior vena cava (SVC) electrical isolation by radiofrequency catheter ablation (RFCA). Methods: First, in a development cohort of patients with atrial fibrillation (AF), the RFCA with 40 W was performed to complete SVC isolation guided by the conduction breakthrough point from the right atrium to SVC. Then, the range of AI value was calculated by offline analysis on different segments of SVC. Lastly, for the validation of AF patients, the safety and effectiveness of SVC isolation with the optimized target range of AI value were evaluated with an additional adenosine test. Results: A total of 101 patients with AF were included in the study (44 patients in the development cohort/57 in the validation cohort). The segmental ablation strategy was applied in 70% of the patients. According to the offline analysis of the AI values in the development cohort, the target AI value range was set as 350–400. The success rate of SVC isolation in the validation cohort was significantly higher than that in the exploration cohort (100% vs. 90.9%, p =.02), and no complications occurred in the exploration cohort. During the adenosine test, the recovery rate of electrical conduction in SVC was significantly lower than that in the pulmonary vein (3.5% vs. 17.5%). Conclusion: The target AI value with a range from 350 to 400 is safe and effective for high‐power RFCA to complete SVC isolation. [ABSTRACT FROM AUTHOR]

Introduction: The IMPACT study established the role of controlled esophageal cooling in preventing esophageal thermal injury during radiofrequency (RF) ablation for atrial fibrillation (AF). The effect of esophageal cooling on ablation lesion delivery and procedural and patient outcomes had not been previously studied. The objective was to determine the effect of esophageal cooling on the formation of RF lesions, the ability to achieve procedural endpoints, and clinical outcomes. Methods: Participants in the IMPACT trial underwent AF ablation guided by Ablation Index (30 W at 350–400 AI posteriorly, 40 W at ≥450 AI anteriorly). A blinded 1:1 randomization assigned patients to the use of the ensoETM® device to keep esophageal temperature at 4°C during ablation or standard practice using a single‐sensor temperature probe. Ablation parameters and clinical outcomes were analyzed. Results: Procedural data from 188 patients were analyzed. Procedure and fluoroscopy times were similar, and all pulmonary veins were isolated. First‐pass pulmonary vein isolation and reconnection at the end of the waiting period were similar in both randomized groups (51/64 vs. 51/68; p = 0.54 and 5/64 vs. 7/68; p = 0.76, respectively). Posterior wall isolation was also similar: 24/33 versus 27/38; p = 0.88. Ablation effect on tissue, measured in impedance drop, was no different between the two randomized groups: 8.6Ω (IQR: 6–11.8) versus 8.76Ω (IQR: 6–12.2; p = 0.25). Arrhythmia recurrence was similar after 12 months (21.1% vs. 24.1%; 95% CI: 0.38–1.84; HR: 0.83; p = 0.66). Conclusions: Esophageal cooling has been shown to be effective in reducing ablation‐related thermal injury during RF ablation. This protection does not compromise standard procedural endpoints or clinical success at 12 months. [ABSTRACT FROM AUTHOR]

Background: Ablation index (AI) is a novel technology of ablation lesion quality to help improve homogeneity of lesion size and continuity. In this study, we aim to evaluate whether AI‐guided PVI improves clinical outcomes compared to CF‐guided PVI in patients with paroxysmal AF (PAF). Methods: Patients undergoing first‐time radiofrequency ablation for PAF were randomized in a 2:1 ratio to two groups: AI‐guided PVI and CF‐guided PVI. In the AI group, AI ≥500 was recommended at the anterior/superior/inferior walls, 350–400 at the posterior wall, and inter‐lesion distance ≤4 mm. The primary endpoint is the freedom from atrial arrhythmia recurrence during 12 months follow‐up, without antiarrhythmic drug therapy (ADT). The key secondary endpoints include intra‐procedural efficiency and peri‐procedural complications. Results: Two hundred twenty five patients were randomized (AI group [n = 149] and CF group [n = 76]). First‐pass isolation rate in AI group was significantly higher than that in CF group (58.3% vs. 43.4%, p =.035). After a median follow‐up of 12.2 months, 154/225 (68.4%) of patients were free from atrial arrhythmia recurrence without ADT, which was higher in AI group compared with CF group, but without significant difference (71.1% vs. 63.2%, p =.253). The incidence of peri‐procedural complications is low and without difference between two groups. Conclusions: AI‐guided ablation provided higher acute efficacy than CF‐guided ablation in PV isolation for patients with paroxysmal AF. The long‐term success rate in AI group was higher than CF group, but did not reach statistical significance. [ABSTRACT FROM AUTHOR]

Introduction: Ablation of atrial fibrillation (AF) with high‐power‐short‐duration (HPSD) radiofrequency (RF) technology is emerging as a new standard of care in many electrophysiology laboratories. While procedural short‐term efficacy and efficiency is very promising, little is known about mid‐ to long‐term effects of HPSD ablation for pulmonary vein isolation (PVI) and left atrial substrate modification. Methods: In a single‐center registry, 412 AF procedures were performed in 400 individual patients using a standardized CLOSE protocol‐guided fixed 50 W HPSD ablation, aiming for an ablation index (AI) of 400 on the posterior and 550 on the anterior wall. Additional substrate‐tailored lines were performed when required. Results: After a mean clinical follow‐up of 337 ± 134 days, 15 patients suffered from AF recurrence beyond the blinding period. Twelve gave consent to the indicated reablation. Here, 11 of 12 patients had chronic isolation of all four pulmonary veins (PV). In three of six patients, a reconnection of additional left atrial ablation lines was revealed. Ten out of 12 patients showed progressive fibrous atrial cardiomyopathy and required additional left atrial substrate modification or reisolation of left‐atrial lines. During the follow‐up no clinical case of atrioesophageal fistula was registered. No PV stenosis after initial HPSD PVI was documented. Conclusions: Patients requiring reablation of AF or other atrial tachycardia after a fixed 50 W HPSD circumferential PVI and substrate modification predominantly suffer from progressive fibrous atrial cardiomyopathy, while PV reconnection appears to be a rare cause of AF recurrence. [ABSTRACT FROM AUTHOR]

Aims: To determine if adapting the ablation index (AI) to the left atrial wall thickness (LAWT), which is a determinant of lesion transmurality, is feasible, effective, and safe during paroxysmal atrial fibrillation (PAF) ablation.Methods and Results: Consecutive patients referred for PAF first ablation. Left atrial wall thickness three-dimensional maps were obtained from multidetector computed tomography and integrated into the CARTO navigation system. Left atrial wall thickness was categorized into 1 mm layers and AI was titrated to the LAWT. The ablation line was personalized to avoid thicker regions. Primary endpoints were acute efficacy and safety, and freedom from atrial fibrillation (AF) recurrences. Follow-up (FU) was scheduled at 1, 3, 6, and every 6 months thereafter. Ninety patients [60 (67%) male, age 58 ± 13 years] were included. Mean LAWT was 1.25 ± 0.62 mm. Mean AI was 366 ± 26 on the right pulmonary veins with a first-pass isolation in 84 (93%) patients and 380 ± 42 on the left pulmonary veins with first-pass in 87 (97%). Procedure time was 59 min (49-66); radiofrequency (RF) time 14 min (12.5-16); and fluoroscopy time 0.7 min (0.5-1.4). No major complication occurred. Eighty-four out of 90 (93.3%) patients were free of recurrence after a mean FU of 16 ± 4 months.Conclusion: Personalized AF ablation, adapting the AI to LAWT allowed pulmonary vein isolation with low RF delivery, fluoroscopy, and procedure time while obtaining a high rate of first-pass isolation, in this patient population. Freedom from AF recurrences was as high as in more demanding ablation protocols. A multicentre trial is ongoing to evaluate reproducibility of these results. [ABSTRACT FROM AUTHOR]

Introduction: Radiofrequency (RF) atrial fibrillation (AF) ablation using a catheter dragging technique may shorten procedural duration and improve durability of pulmonary vein isolation (PVI) by creating uninterrupted linear ablation lesions. We compared a novel AF ablation approach guided by Grid annotation allowing for "drag lesions" with a standard point‐by‐point ablation approach in a single‐center randomized study. Methods: Eighty‐eight paroxysmal or persistent AF patients were randomized 1:1 to undergo RF‐PVI with either a catheter dragging ablation technique guided by Grid annotation or point‐by‐point ablation guided by Ablation Index (AI) annotation. In the Grid annotation arm, ablation was visualized using 1 mm³ grid points coloring red after meeting predefined stability and contact force criteria. In the AI annotation arm, ablation lesions were created in a point‐by‐point fashion with AI target values set at 380 and 500 for posterior/inferior and anterior/roof segments, respectively. Patients were followed up for 12 months after PVI using ECGs, 24‐h Holter monitoring and a mobile‐based one‐lead ECG device. Results: Procedure time was not different between the two randomization arms (Grid annotation 71 ± 19 min, AI annotation 72 ± 26 min, p =.765). RF time was significantly longer in the Grid annotation arm compared with the AI annotation arm (49 ± 8 min vs. 37 ± 8 min, respectively, p <.001). Atrial tachyarrhythmia recurrence was documented in 10 patients (23%) in the Grid annotation arm compared with 19 patients (42%) in the AI annotation arm with time to recurrence not reaching statistical significance (p =.074). Conclusions: This study shows that a Grid annotation‐guided dragging approach provides an alternative to point‐by‐point RF‐PVI using AI annotation. [ABSTRACT FROM AUTHOR]

Introduction: Successful pulmonary vein isolation (PVI) for atrial fibrillation (AF) depends on the formation of durable transmural lesions. Recently, novel indices have emerged to guide lesion delivery. The aim of the systematic review of literature was to determine AF recurrence following ablation guided by indices incorporating force, power and time, and compare acute procedural outcomes and 12-month AF recurrence with ablation guided by contact force (CF) guided only.Methods: PubMed, EMBASE, and Web of Science Core Collection databases were searched on 27 January 2020 using the keywords; catheter ablation, ablation index (AI), lesion size index (LSI), contact force, atrial fibrillation.Results: After exclusions, seven studies were included in the analysis. AI-guided catheter ablation was associated with a 91% (n=5, 0.91 95% CI; 0.88-0.93) and 80% (n=5, 0.80, 95% CI; 0.77-0.84) freedom from AF at 12 months with and without the use of anti-arhythmic drugs respectively. As compared to CF guided ablation, AI-guided catheter ablation was associated with a 49% increase in successful first pass isolation (n=3; RR: 1.49, 95% CI; 1.38, 1.61), a 50% decrease in number of acute reconnections (n=4; RR: 0.50, 95% CI; 0.39-0.65) and a 22% (n=4, RR: 1.22, 95% CI; 1.10-1.35) increase in AF freedom without anti-arrhythmic drugs at 12 months.Conclusions: Radiofrequency ablation guided by AI was associated with higher successful first pass isolation and lower rates of acute reconnection which translates to greater freedom from AF at 12 months [CRD42019131469]. [ABSTRACT FROM AUTHOR]

Aim: Reconnection of the pulmonary veins (PVs) is the most common reason for the recurrence of atrial fibrillation (AF). The ablation index is a marker of ablation lesion quality that achieves high percentages of first-pass isolation and improved AF ablation results. Most operators use a double transseptal approach with confirmation of PV isolation with a circular mapping catheter. In the present study we aimed to show that an ablation index-guided procedure using a single transseptal approach and ablation catheter only would achieve adequate PV isolation while demonstrating the critical role of the carina in PV isolation.Method: Sixty-six (66) consecutive patients with paroxysmal AF were included. Thirty-four (34) patients underwent wide antral circumferential ablation (WACA-only) and 32 underwent WACA+ (WACA + empiric carina isolation). All procedures were performed via single transseptal approach. Pulmonary vein isolation was confirmed with the use of a circular mapping catheter in both groups.Results: Compared to WACA-only, WACA+ increased the odds of PV isolation from 65% to 94% (p=0.011). In the WACA-only procedure, ablation of the carina was needed to achieve PV isolation. At the 18-month follow-up (interquartile range 15.2-20.8 months), freedom from AF was 84% for the entire cohort.Conclusions: Our study confirmed the high success rate of PV isolation using the ablation index and showed that this can be achieved via a single transseptal crossing. Our study confirmed the role of the carina in PV isolation. [ABSTRACT FROM AUTHOR]

Introduction: Ablation index (AI)‐guided radiofrequency ablation has been increasingly used for the treatment of drug‐resistant paroxysmal atrial fibrillation (AF)，but the optimal AI targets remain to be determined. We aimed to examine the efficacy and safety of catheter ablation guided by moderate AI values but more strict procedural endpoints in patients with paroxysmal AF. Methods: We conducted a retrospective review of a consecutive series of patients who received their first AI‐guided ablation for paroxysmal AF from 2017 to 2018. The standard procedural protocol recommends AI targets as follows: anterior: 400–450; posterior: 280–330; and roof/inferior wall: 380–430. After circumferential pulmonary vein isolation (PVI), we performed bipolar pacing along the ablation line, adenosine triphosphate (ATP)‐provocation, and waited for 30 min to verify PVI. The primary clinical outcome was the rate of freedom from AF recurrence at 12 months. Results: A total of 140 consecutive patients were included. The mean procedure and ablation times were 132.2 ± 30.2 min and 24.2 ± 7.9 min, respectively. The first‐pass isolation and final isolation rates were documented in 49.3% and in 100% of the patients, respectively. At 12 months, single‐procedure freedom from atrial tachyarrhythmias was observed in 92.1% of patients. No major procedure‐related complications were encountered. Conclusions: Moderate AI‐guided catheter ablation is highly effective for the treatment of drug‐refractory paroxysmal AF in real‐world settings. Over 90% of patients achieved single‐procedure arrhythmia‐free survival at 1 year. The outcome was obtained without major complications and the procedure involved relatively short procedure and ablation times. [ABSTRACT FROM AUTHOR]

Aims: The safety of Ablation Index (AI)-guided 50 W ablation for atrial fibrillation (AF) remains uncertain, and mid-term clinical outcomes have not been described. The interplay between AI and its components at 50 W has not been reported.Methods and Results: Eighty-eight consecutive AF patients (44% paroxysmal) underwent AI-guided 50 W ablation. Procedural and 12-month clinical outcomes were compared with 93 consecutive controls (65% paroxysmal) who underwent AI-guided ablation using 35-40 W. Posterior wall isolation (PWI) was performed in 44 (50%) and 23 (25%) patients in the 50 and 35-40 W groups, respectively, P < 0.001. The last 10 patients from each group underwent analysis of individual lesions (n = 1230) to explore relationships between different powers and the AI components. Pulmonary vein isolation was successful in all patients. Posterior wall isolation was successful in 41/44 (93.2%) and 22/23 (95.7%) in the 50 and 35-40 W groups, respectively (P = 0.685). Radiofrequency times (20 vs. 26 min, P < 0.001) and total procedure times (130 vs. 156 min, P = 0.002) were significantly lower in the 50 W group. No complication or steam pop was seen in either group. Twelve-month freedom from arrhythmia was similar (80.2% vs. 82.8%, P = 0.918). A higher proportion of lesions in the 50 W group were associated with impedance drop >7 Ω (54.6% vs. 45.5%, P < 0.001). Excessive ablation (AI >600 anteriorly, >500 posteriorly) was more frequent in the 50 W group (9.7% vs. 4.3%, P < 0.001).Conclusion: Ablation Index-guided 50 W AF ablation is as safe and effective as lower powers and results in reduced ablation and procedure times. Radiofrequency lesions are more likely to be therapeutic, but there is a higher risk of delivering excessive ablation. [ABSTRACT FROM AUTHOR]

Aims: Ablation index (AI) is a marker of lesion quality during catheter ablation that incorporates contact force, time, and power in a weighted formula. This index was originally developed for pulmonary vein isolation as well as other left atrial procedures. The aim of our study is to evaluate the feasibility and efficacy of the AI for the ablation of the cavotricuspid isthmus (CTI) in patients presenting with typical atrial flutter (AFL).Methods and Results: This prospective multicentre non-randomized study enrolled 412 consecutive patients with typical AFL undergoing AI-guided cavotricuspid isthmus ablation. The procedure was performed targeting an AI of 500 and an inter-lesion distance measurement of ≤6 mm. The primary endpoints were CTI 'first-pass' block and persistent block after a 20-min waiting time. Secondary endpoints included procedural and radiofrequency duration and fluoroscopic time. A total of 412 consecutive patients were enrolled in 31 centres (mean age 64.9 ± 9.8; 72.1% males and 27.7% with structural heart disease). The CTI bidirectional 'first-pass' block was reached in 355 patients (88.3%), whereas CTI block at the end of the waiting time was achieved in 405 patients (98.3%). Mean procedural, radiofrequency, and fluoroscopic time were 56.5 ± 28.1, 7.8 ± 4.8, and 1.9 ± 4.8 min, respectively. There were no major procedural complications. There was no significant inter-operator variability in the ability to achieve any of the primary endpoints.Conclusion: AI-guided ablation with an inter-lesion distance ≤6 mm represents an effective, safe, and highly reproducible strategy to achieve bidirectional block in the treatment of typical AFL. [ABSTRACT FROM AUTHOR]

Aims: Radiofrequency catheter ablation (RFCA) represents an effective option for idiopathic premature ventricular contractions (PVCs) treatment. Ablation Index (AI) is a novel ablation marker incorporating RF power, contact force, and time of delivery into a single weighted formula. Data regarding AI-guided PVCs RFCA are currently lacking. Aim of the study was to compare AI-guided and standard RFCA outcomes in patients with PVCs originating from the right ventricle outflow tract (RVOT).Methods and Results: Consecutive patients undergoing AI-guided RFCA of RVOT idiopathic PVCs were prospectively enrolled. Radiofrequency catheter ablation was performed following per-protocol target cut-offs of AI, depending on targeted area (RVOT free wall AI cut-off: 590; RVOT septum AI cut-off: 610). A multi-centre cohort of propensity-matched (age, sex, ejection fraction, and PVC site) patients undergoing standard PVCs RFCA was used as a comparator. Sixty AI-guided patients (44.2 ± 18.0 years old, 58% male, left ventricular ejection fraction 56.2 ± 3.8%) were enrolled; 34 (57%) were ablated in RVOT septum and 26 (43%) patients in the RVOT free wall area. Propensity match with 60 non-AI-guided patients was performed. Acute outcomes and complications resulted comparable. At 6 months, arrhythmic recurrence was more common in non-AI-guided patients whether in general (28% vs. 7% P = 0.003) or by ablated area (RVOT free wall: 27% vs. 4%, P = 0.06; RVOT septum 29% vs. 9% P = 0.05). Ablation Index guidance was associated with improved survival from arrhythmic recurrence [overall odds ratio 6.61 (1.95-22.35), P = 0.001; RVOT septum 5.99 (1.21-29.65), P = 0.028; RVOT free wall 11.86 (1.12-124.78), P = 0.039].Conclusion: Ablation Index-guidance in idiopathic PVCs ablation was associated with better arrhythmic outcomes at 6 months of follow-up. [ABSTRACT FROM AUTHOR]

Background: Recent studies have shown the improvement in long‐term effectiveness with standardized pulmonary vein isolation (PVI) aimed at creating durable and contiguous lesions with VISITAG SURPOINT (VS) in paroxysmal atrial fibrillation (PAF). Objective: We aimed to assess efficacy of PVI alone strategy using VS in non‐PAF patients and evaluate factors associated with corresponding clinical outcomes. Methods: Consecutive patients who underwent PVI for persistent/long‐standing persistent AF between May 2017 to July 2019 were studied retrospectively. PVI was performed with 30–50 W guided by VS (posterior target: 400–500, anterior target: 500). Left atrial voltage maps were created during atrial pacing after PVI. Results: A total of 140 patients (119 males, age 62 ± 10 years, long‐standing persistent AF: 35) were included and followed for median of 454 days. No adverse events were reported in any patients during periprocedural and follow‐up period of up to 28 months. Kaplan–Meier analysis estimated that freedom from atrial tachycardia or AF (AT/AF) without antiarrhythmics at 1‐year was 70%. Radiofrequency delivery with higher power was associated with increased first‐pass isolation rate, but not with freedom from AT/AF. In multivariate analysis, long‐standing persistent AF and % low‐voltage zone (%LVZ) were independent predictors of clinical outcome. The best cut‐off value of %LVZ for predicting AT/AF recurrence was 3.24%. Freedom from AT/AF was 88% in patients with persistent AF and %LVZ < 3.24%, while 27% in those with long‐standing persistent AF and %LVZ ≥ 3.24%. Conclusions: PVI alone using VS was associated with excellent 1‐year success in patients with persistent AF and %LVZ < 3.24%, but was insufficient in those with long‐standing persistent AF and/or %LVZ ≥ 3.24%. [ABSTRACT FROM AUTHOR]

Background: Ablation index (AI) is a new lesion quality marker that has been demonstrated to allow a high single‐procedure arrhythmia‐free survival in single‐center studies. This prospective, multi‐center study was designed to evaluate the reproducibility of pulmonary vein (PV) isolation guided by the AI. Methods: A total of 490 consecutive patients with paroxysmal (80.4%) and persistent AF underwent first time PV isolation and were divided in four study groups according to operator's preference in choosing the ablation catheter (a contact force (ST) or contact force surround flow (STSF) catheter) and the AI setting (330‐450 or 380‐500 at anterior wall or posterior wall, respectively). Results: At 12 months a high rate of freedom from AF recurrences was observed in patients with both paroxysmal and persistent AF (91% vs 83.3%; P =.039). There was no difference in the rate of AF recurrence among the four study groups (4.5% in group ST330‐450, 12.2% in group ST 380‐500, 14.9% in group STSF330‐450, 9.4% in group STSF380‐500; P =.083). Recurrence was also similar between patients treated with a ST (8%) or STSF catheter (12.1%; P =.2), and within patients targeting an AI settings of 330 to 450 (10.9%) or 380 to 500 (10.3%; P =.64). In patients with paroxysmal AF, there was no difference (P =.12) in the 1‐year freedom from AF recurrence among 14 operators that performed ≥10 ablation procedure. Conclusions: An ablation protocol respecting strict criteria for contiguity and quality lesion resulted in high rate of 1‐year freedom from AF recurrence, irrespective of the ablation catheters, AI settings, and operator. [ABSTRACT FROM AUTHOR]

Introduction: Ablation Index, also known as VISITAG SURPOINT™, is a novel lesion-quality marker that improves outcomes in radiofrequency (RF) catheter ablation of atrial fibrillation (AF). There is no direct evidence on the comparative effectiveness of RF ablation with Ablation Index and cryoballoon (CB). The objective of the present study was to conduct a matching-adjusted indirect comparison (MAIC) using individual patient-level data (IPD) to compare the effectiveness of RF ablation with Ablation Index to that of CB on recurrence of atrial arrhythmias 12 months after catheter ablation in patients with paroxysmal AF (PAF).Methods: Individual patient-level data for RF ablation with Ablation Index were obtained from two studies: Solimene et al. [J Interv Card Electrophysiol 54(1):9-15, 2019] and Hussein et al. [J Cardiovasc Electrophysiol 28(9):1037-1047, 2017]. Comparable CB studies identified from a systematic literature review were pooled. Prognostic variables for adjustment were ranked a priori by several practicing electrophysiologists. In the absence of a common treatment arm between the Ablation Index and CB studies, an unanchored MAIC was conducted. Primary analysis compared the Solimene et al. study to pooled CB studies. A secondary analysis compared pooled RF ablation with Ablation Index studies to pooled CB studies. Several scenario and sensitivity analyses were conducted.Results: Primary analyses showed statistically significant reductions in the rate of arrhythmia recurrence with RF ablation with Ablation Index compared to CB in unmatched, unadjusted (HR 0.50, 95% CI 0.27-0.95) and matched (0.42, 0.21-0.86) analyses. Greater reductions in the rate of arrhythmia recurrence that favored RF ablation with Ablation Index were observed after matching and adjusting for age (0.41, 0.20-0.85), age and left ventricular ejection fraction (0.37, 0.16-0.88), and age, sex, and left ventricular ejection fraction (0.30, 0.13-0.71). Secondary and sensitivity analyses showed similar reductions.Conclusions: Radiofrequency ablation with Ablation Index was associated with reductions in recurrence of atrial arrhythmias at 12 months compared to CB in unmatched and unadjusted, matched, and matched and adjusted comparisons. [ABSTRACT FROM AUTHOR]

Backgrounds: Ablation index (AI) is useful to complete circumferential pulmonary vein isolation (CPVI) for atrial fibrillation (AF), but the role of radiofrequency power in AI‐guided CPVI remains to be elucidated. Methods: We investigated 60 patients with AF undergoing AI‐guided CPVI (mean age, 66 ± 9 years; nonparoxysmal AF in 16). The first 40 patients were randomly assigned to low‐power (LP; n = 20) and medium‐power (MP; n = 20) groups and the following 20 patients to high‐power (HP). In LP, radiofrequency (RF) application was done at 30 W at the anterior and 20 W at the posterior left atrial (LA) wall, while in MP, it was at 40 W at the anterior and 30 W at the posterior LA wall. In HP, 50 W was applied at the anterior, 40 W at posterior LA wall and 30 W on the esophagus. At each ablation point, target AI was 400 at the anterior, 360 at the posterior LA wall, and 260 on the esophagus. Results: The time to complete both‐side CPVI was shortest in HP (median, 40 minutes, interquartile range [IQR], 28‐63) followed by MP (58 [49‐83] minutes, P = .008 vs HP) and LP (84 [72‐93] minutes, P = .002 vs MP). Higher RF power application significantly increased first‐pass isolation rate (55% in LP, 80% in MP and 85% in HP, P = .002) and decreased LA‐PV reconnection rate (10% in LP, 8% in MP, and 0% in HP, P = .03). Conclusion: In AI‐guided PVI, the HP RF application can shorten the time to complete PVI with a high rate of first‐pass isolation and a low rate of LA‐PV reconnection. [ABSTRACT FROM AUTHOR]

Introduction: Ablation index (AI), a novel parameter defining energy application at single ablation lesions, calculated by integration of ablation time, energy, catheter stability, and contact force, has been documented to be associated with effective lesions and higher ablation efficacy. Using a prespecified target AI in addition to acute lesion efficacy may affect local collateral damage like esophageal thermal injury when used for guiding radiofrequency (RF) ablation at the posterior left atrial (LA) wall. Methods and Results: Consecutive patients undergoing first AF ablations using AI were included. Ablation energy was reduced to 25 W when ablating at posterior LA wall. Two different individually defined AI target values were used (300 and 350 for posterior wall ablation). Esophageal endoscopy (EE) was performed 1 to 3 days after ablation procedure to document and categorize endoscopically detected esophageal thermal lesion (EDEL). Two‐hundred and eleven consecutive patients with postprocedural EE were included. Incidence of EDEL was 14% (29 of 211 patients; mild category 1 lesions in 22 of 29 patients (76%) and severe category 2 lesions (ulcers > 5 mm) in 7 of 29 patients (24% of EDEL group, 3% of total group). Ablation time at posterior LA wall (9.5 vs 9.0 minutes [P = .67]) was comparable in patients with and without EDEL. Conclusion: LA posterior wall RF ablation adopting AI ≤350 was associated with 14% esophageal thermal injury including 3% of severe esophageal thermal ulcers. This incidence is comparable to historic control groups with non AI–guided AF ablation. [ABSTRACT FROM AUTHOR]

Background: Ablation index (AI) has been evaluated as guidance quality marker for pulmonary vein isolation, but not for linear ablation of the cavotricuspid isthmus (CTI) for typical right atrial flutter (AFL). We thus studied the feasibility and effectiveness of AI‐guided CTI for AFL. Methods: Procedural and 6‐month outcomes of ablation for AFL were retrospectively compared between consecutive patients undergoing either AI‐guided ablation of CTI (n = 43; AI target of 500 for anterior 2/3 segments and 400 for posterior 1/3 segments) or contact force (CF)‐guided ablation (n = 42) at a single center. Each Visitag dataset from all patients in each group was analyzed. Results: AI guidance vs CF guidance was associated with: higher first‐pass conduction block of CTI (93.0% vs 76.2%, P = .03) with similar ablation time; similar acute spontaneous CTI reconnection 2.3% vs 9.5%, P = .343); fewer radiofrequency (RF) applications (10.1 ± 2.8 vs 11.5 ± 3.0, P = .031) needed to achieve CTI directional block; significantly higher mean ablation time, impedance drop, force time integral and AI and similar mean CF and power of each VisiTag point. One inguinal hematoma and one pseudoaneurysm developed in the AI and CF groups, respectively. Recurrent AFL was recorded in two (4.7%) AI‐group patients and four (9.5%) CF‐group patients (P = .650). Conclusion: AI‐guided ablation of CTI line for AFL appears feasible and effective with similar ablation time, fewer RF applications, a higher rate of first‐pass conduction block, and no additional complications. [ABSTRACT FROM AUTHOR]

Background: Atrial fibrillation (AF) ablation outcome is still operator dependent. Ablation Index (AI) is a new lesion quality marker that has been demonstrated to allow acute durable pulmonary vein (PV) isolation followed by a high single‐procedure arrhythmia‐free survival. This prospective, multicenter study was designed to evaluate the reproducibility of acute PV isolation guided by the AI. Methods: A total of 490 consecutive patients with paroxysmal (80.4%) and persistent AF underwent first time PV encircling and were divided in four study groups according to operator preference in choosing the ablation catheter (a contact force [ST] or contact force surround flow [STSF] catheter) and the AI setting (330 at posterior and 450 at anterior wall or 380 at posterior and 500 at anterior wall). Radiofrequency was delivered targeting interlesion distance ≤6 mm. Results: The rate of first‐pass PV isolation (ST330 90 ± 16%, ST380 87 ± 19%, STSF330 90 ± 17%, STSF380 91 ± 15%, P = .585) was similar among the four study groups, whereas procedure (ST330 129 ± 44 minutes, ST380 144 ± 44 minutes, STSF330 120 ± 72 minutes, STSF380 125 ± 73 minutes, P <.001) and fluoroscopy time (ST330 542 ± 285 seconds, ST380 540 ± 416 seconds, STSF330 257 ± 356 seconds, STSF380 379 ± 454 seconds, P < 0.001) significantly differed. The difference in the rate of first‐pass isolation was not statistical different (P = .06) among the 12 operators that performed at least 15 procedures. Conclusions: An ablation protocol respecting strict criteria for contiguity and quality lesion results in high and comparable rate of acute PV isolation among operator performing ablation with different catheters, AI settings, procedure, and fluoroscopy times. [ABSTRACT FROM AUTHOR]

Background: Interlesion distance and ablation index (AI) have been proposed as parameters of radiofrequency (RF) lesion durability. This study analyzes the relationship between RF parameters of automatically acquired lesion tags and late reconnections in repeat pulmonary vein isolation (PVI) procedures. Methods: One hundred fifty‐seven patients underwent contact force (CF)‐guided PVI with automatic acquisition of RF lesions. During follow‐up, 21 patients underwent a repeat PVI procedure. The relationship between RF parameters (power, CF, impedance drop, and AI) of the initial PVI procedure and reconnections observed at repeat PVI was analyzed. Visual gap was defined as the existence of a discontinuity between two RF lesions automatically acquired in the initial PVI procedure. Regional values of AI associated with lesion durability were identified. Results: Twenty‐one patients were included. Three hundred thirty‐six segments and 2507 RF lesions were analyzed. The median interval between the initial and repeat PVI procedures was 17 (11‐24) months. All patients showed ≥1 reconnected segment. Sixty‐three segments (18.7%) were reconnected. Reconnected segments showed visual gaps more frequently than non‐reconnected segments (66.6% vs 17.6%; P < .001; negative predictive value 91.4%). The mean distance of visual gaps was 8 ± 2.8 mm. No differences were observed in power (31.4 ± 4.7 W vs 31 ± 4.1 W; P = .573), CF (14.4 ± 5.3 g vs 15.4 ± 5.4 g; P = .315), and impedance drop (6.9 ± 5.2 ohms vs 6.5 ± 3.8 ohms; P = .576) between reconnected and non‐reconnected segments. Among segments without visual gap, the minimum AI value was significantly higher in the non‐reconnected segments (325 ± 96.1 vs 204.7 ± 78.5; P < .001). No reconnections were observed in segments without visual gap and minimum AI ≥ 330/220 in anterior/posterior wall, respectively. Conclusions: Contiguity between automatically acquired RF lesions and minimum AI value are the main determinants of long‐term PVI durability. [ABSTRACT FROM AUTHOR]

Background: Pulmonary vein isolation (PVI) using high power delivered by SmartTouch Surround Flow (STSF) catheters guided by ablation index (AI) was evaluated in a multicenter registry. Methods: Patients with paroxysmal AF underwent PVI with STSF catheters using 30 W on the posterior wall and 40 W elsewhere. AI targets were 350 posterior walls and 450 elsewhere. Procedures were compared with controls using conventionally irrigated contact force‐sensing catheters using conventional powers (25 W posterior wall and 30 W elsewhere) guided by force‐time integral (no agreed targets). The waiting period of 30 minutes was observed before adenosine administration to assess acute pulmonary vein (PV) reconnection. Results: One hundred patients from four centers were included: 50 patients in the high power ablation index (HPAI) group and 50 controls. Procedure time was 22% shorter in the HPAI group (156 [133.8‐179] vs 199 [178.5‐227] minutes; P < 0.001). Duration of the radiofrequency application was 37% shorter in the HPAI group (27.2 [21.5‐35.8] vs 43.2 [35.1‐52.1] minutes; P < 0.001). Acute PV reconnection was reduced (28 of 200 [14%] vs 48 of 200 [24%] veins; P = 0.015). Reconnection was predicted by a largest interlesion distance greater than 6 mm, a lesion with impedance drop less than 2.5 Ω, contact force less than 6 g, or less than 68% of the regional AI target (all P < 0.001). Freedom from atrial arrhythmia at 1 year off antiarrhythmic drugs after a single procedure was 78% in the HPAI group vs 64% in the control group (P = 0.186). Conclusion: High‐powered ablation guided by AI was safe and led to shorter procedure times with reduced acute PV reconnection compared with conventional ablation. [ABSTRACT FROM AUTHOR]

Objective: Ablation index (AI) is an effective ablation quality marker. Impedance is also an important factor for lesion formation. The present study evaluated the influence of the baseline impedance in the effect of ablation for atrial fibrillation (AF) guided by AI.Methods: This was a retrospective study. 101 patients with paroxysmal AF (PAF) were enrolled. All patients underwent radiofrequency ablation guided by the same AI strategy. The ablation strategy was pulmonary vein (PV) isolation with non-PV triggers ablation. The baseline impedance of the ablation points was recorded. The patients were followed up every 3 months or so.Results: During a median follow-up of 12 (4-14) months, freedom from AF/atrial tachycardia recurrence were 82.2%. No difference existed in baseline characteristics between the success group and the recurrence group. The average baseline impedance was 124.3 ± 9.7 Ω. The baseline impedance of the ablation points in success group was lower compared to the recurrence group (122.9 ± 9.4 vs. 130.5 ± 8.8 Ω, P < 0.01). The ratio of impedance drop in the success group was higher than the recurrence group ([8.8 ± 1.4]% vs. [8.1 ± 1.2]%, P = 0.03). Multivariate analysis revealed that baseline impedance, PAF duration and AI were the independent predictors of AF recurrence. The cumulative free of recurrence rate of low-impedance group (≤ 124 Ω, n = 54) was higher than that of high-impedance group.Conclusion: Baseline impedance correlates with clinical outcome of radiofrequency ablation for PAF guided by AI. Higher impedance in the same AI strategy may result in an ineffective lesion which probably causes recurrence. [ABSTRACT FROM AUTHOR]