Ablation Index Research Articles

Tailored Target Ablation Index Guided Pulmonary Vein Isolation in Treating Paroxysmal Atrial Fibrillation: A Single Center Randomized Study in Asian Population (AI-Asian-I).

ObjectiveTo evaluate the efficacy and safety of lower ablation indexes (AI) guided pulmonary vein isolation (PVI) in treating paroxysmal atrial fibrillation (AF).MethodsNinety patients with paroxysmal AF scheduled for radiofrequency ablation were randomly divided into three groups. The AI targets for PVI were as follows: In group A/B/C, 550/500/450 for roof and anterior wall, and 400/350/300 for posterior/inferior wall. The first-pass PVI rate, ablation time, complications and recurrence of atrial tachyarrhythmia (ATa) were compared.ResultsThe mean age was 62.5 years (male: 63.0%), mean body mass index (BMI): 24.35 ± 3.66 kg/m2. The baseline characteristics were comparable. There was no significant difference in the first-pass PVI rate among the three groups (left-sided-PV: 66.7% vs. 80% vs. 73.3%, P = 0.51; right-sided-PV: 70% vs. 83.3% vs. 73.3%, P = 0.64), also with similar gap rate during the procedural waiting time. At 1-year follow-up there was no significant difference in the recurrence rate of ATa among the three groups (10% vs. 13.3% vs. 13.3%, P = 1.00). The ablation time in the Group C was significantly less than that in the other two groups (47.8 min. vs. 47.0 min. vs. 36.6 min, P < 0.001). Higher AI seemed to link a non-significant trend toward higher rate of pericardial effusion (group A + B vs. group C:6.7% vs. 0%, P = 0.30), although the rate of overall complications was not different among the three groups.ConclusionThis randomized study shows that, a relatively lower target AI guided ablation may be similarly effective to achieve PVI with significantly reduced ablation time and obtain similar clinical outcome in treating paroxysmal AF in Asian population.Clinical Trial Registration[www.ClinicalTrials.gov], identifier [NCT:04549714].

Circumferential Pulmonary Vein Isolation Plus Low-Voltage Area Modification in Persistent Atrial Fibrillation: The STABLE-SR-II Trial.

Benefits of adjunctive ablation strategies beyond circumferential pulmonary vein isolation (CPVI) are uncertain in patients with persistent atrial fibrillation (PeAF). This study sought to compare clinical outcomes of CPVI plus low-voltage area (LVA) modification during STABLE-SR (SubsTrate ABlation in the LEft Atrium during Sinus Rhythm) vs circumferential pulmonary vein isolation (CPVI) alone in patients with PeAF. From March 2018 to August 2019, 300 patients with PeAF who underwent de novo ablation were recruited and prospectively randomized to either STABLE-SR group (n=150) or CPVI alone (n=150) group. In the STABLE-SR group, after CPVI, high-density voltage mapping of left atrium (LA) was performed during sinus rhythm, and additive ablation targeted LVA and complex electrograms, if any were present. All the ablations were titrated by ablation index. The primary endpoint was freedom from documented atrial arrhythmias lasting for≥30s without the use of antiarrhythmic drugs, after a single ablation procedure and blanking period of 3months. After 18months, atrial-arrhythmia-free survival did not differ significantly between STABLE-SR group and CPVI alone group (67.2% vs 67.4%; HR: 0.89; 95%CI: 0.55-1.36; P = 0.52). Only around one-half of the patients (50.2%) had abnormal LA substrate with a medium LVA burden of 4.6% (2.1%-9.5%). However, the success rate differs dramatically between patients with normal vs abnormal LA substrate (84.8% vs 60.9%; P< 0.001). Additional LVA ablation did not improve successful rates of CPVI in this PeAF cohort, of whom one-half had normal LA substrate. Voltage map could identify patients with PeAF with normal LA substrate who can achieve excellent rhythm control with CPVI alone. (CPVI Alone Versus CPVI Plus Electrophysiological Substrate Ablation in the LA During SR for the Treatment of Non-PAF [STABLE-SR_II]; NCT03448562).

Atrial Arrhythmia Ablation in Patients With D-Transposition of the Great Arteries and Atrial Switch.

Patients with D-transposition of the great arteries and atrial switch have a high incidence of atrial arrhythmias. We sought to analyze the arrhythmia substrate, ablation strategies, and outcomes for catheter ablation in this population. An in-depth analysis of all clinical and procedural data in patients with D-transposition of the great arteries, atrial baffles, and atrial arrhythmia ablation was performed. A cohort of 32 patients (72% male, mean age 38±7 years) underwent ablation for non-AV nodal reentrant tachycardia atrial arrhythmias, and 4 patients underwent AV nodal reentrant tachycardia ablation. Cavotricuspid isthmus flutter (CTI-flutter) was the most common arrhythmia, encountered in 75% of patients, followed by scar-related intraatrial reentrant tachycardia (non-CTI intraatrial reentrant tachycardia, 53%) and focal atrial tachycardia (focal atrial tachycardia, 6%). Among the 32 patients, 26 underwent 31 procedures at our institution. For patients with prior outside intervention, the index ablation at our institution revealed CTI-dependent flutter in 3/5 cases. However, redo ablation after an index ablation with demonstrated bidirectional CTI block revealed different/new arrhythmia substrates (80% non-CTI intraatrial reentrant tachycardia, 40% focal atrial tachycardia). Achieving bidirectional block across the CTI often required ablating on both sides of the baffle (retroaortic access, 81%; using a baffle leak, 11.5%; or transbaffle puncture, 7.7%). Combined approaches were necessary in 19% to reach the critical tissue. Acute procedural success was 81%, and recurrence was documented in 58% of patients. Despite recurrence, clinical arrhythmia burden was significantly reduced post-ablation (P<0.001), with rare episodes, amenable to antiarrhythmic therapy. Redo ablation was required in 5 (19%) patients and uncovered new arrhythmia substrates. AV nodal reentrant tachycardia ablation also required transbaffle approaches in 3/4 patients. CTI-dependent flutter was the most common arrhythmia in patients with Dextro-Transposition of the Great Arteries and atrial switch. Transbaffle approaches were often necessary, and, provided that bidirectional CTI block was achieved at the index ablation, late recurrence was due to different arrhythmia mechanisms. Despite recurrence, ablation was associated with significant clinical improvement.

EE289 Ablation Index in Catheter Ablation of Atrial Fibrillation: A Cost-Utility Analysis in Belgium and Germany

Catheter ablation is a commonly used therapy for symptomatic nonvalvular atrial fibrillation (AF). VISITAG SURPOINT™ (Ablation Index/AI) is a module that allows annotation and tagging of ablation applications. Ablation with AI is associated with a significant reduction in atrial arrhythmia recurrence at 12 months versus ablation with catheters alone in meta-analyses. The objective of this study was to assess the cost-effectiveness of AI for catheter ablation versus ablation with catheters alone in adult patients with drug-refractory paroxysmal or persistent AF from the German and Belgium healthcare payer’s perspectives.

Assessment of the need of a waiting period after pulmonary vein isolation with the ablation index software.

Since the widespread availability of contact-force sensing catheters, the need for a waiting period after pulmonary vein isolation (PVI) has not been reassessed. We aim to evaluate whether a waiting period is still necessary after PVI guided by the ablation Index (AI). Prospective, multicenter, randomized study of consecutive patients referred for paroxysmal atrial fibrillation (AF) ablation from May 2019 to February 2020. Patients were randomized in a 1:1 ratio to PVI with versus without a waiting period of 20 min. Acute pulmonary vein (PV) reconnection after adenosine challenge was the primary endpoint. A per-protocol analysis was designed to determine whether a strategy of dismissing the waiting period after PVI was noninferior to waiting for 20 min for identifying acute PV reconnection. PVI was guided by tailored AI values and an interlesion distance ≤6 mm. During the enrollment period, 167 patients (56% males, mean age of 57 ± 14 years) fulfilled the study inclusion criteria - 84 patients (308 PV) in the waiting period group (Group A) and 83 patients (314 PV) in the group without a waiting period (Group B). Acute PV reconnection was identified in 3.8% (95% confidence interval [CI], 1.7%-5.9%) of PVs in the study group B compared to 2.9% (95% CI, 1.0%-4.8%) of PVs in the Group A (p = .002 for non-inferiority). At 1-year follow-up, there was no significant difference in arrhythmia recurrence between groups (9.5% in Group A vs. 9.6% in Group B, hazard ratio: 1.03 [95% CI, 0.39-2.73], p = .98). In paroxysmal AF patients submitted to ablation, a tailored PVI guided by the AI rendered a 20-minwaiting period unnecessary.

Shorter distance between the esophagus and the left atrium is associated with higher rates of esophageal thermal injury after radiofrequency ablation.

Esophageal thermal injury (ETI) is a known and potentially serious complication of catheter ablation for atrial fibrillation. We intended to evaluate the distance between the esophagus and the left atrium posterior wall (LAPW) and its association with esophageal thermal injury. A retrospective analysis of 73 patients who underwent esophagogastroduodenoscopy (EGD) after LA radiofrequency catheter ablation for symptomatic atrial fibrillation and pre-ablation magnetic resonance imaging (MRI) was used to identify the minimum distance between the inner lumen of the esophagus and the ablated atrial endocardium (pre-ablation atrial esophageal distance; pre-AED) and occurrence of ETI. Parameters of ablation index (AI, Visitag Surpoint) were collected in 30 patients from the CARTO3 system and compared with assess if ablation strategies and AI further impacted risk of ETI. Pre-AED was significantly larger in patients without ETI than those with ETI (5.23 ± 0.96 mm vs. 4.31 ± 0.75 mm, p < .001). Pre-AED showed high accuracy for predicting ETI with the best cutoff value of 4.37 mm. AI was statistically comparable between Visitag lesion markers with and without associated esophageal late gadolinium enhancement (LGE) detected by postablation MRI in the low-power long-duration ablation group (LPLD, 25-40 W for 10-30 s, 393.16 [308.62-408.86] vs. 406.58 [364.38-451.22], p = .16) and high-power short-duration group (HPSD, 50 W for 5-10 s, 336.14 [299.66-380.11] vs. 330.54 [286.21-384.71], p = .53), respectively. Measuring the distance between the LA and the esophagus in pre-ablation LGE-MRI could be helpful in predicting ETI after LAPW ablation.

High-power short-duration ablation index–guided pulmonary vein isolation protocol using a single catheter

BackgroundCatheter ablation for atrial fibrillation (AF) is the most commonly performed electrophysiological procedure. To improve healthcare utilization, we aimed to compare the efficacy, efficiency, and safety of a minimalistic, streamlined single catheter ablation approach using a high-power short-duration ablation index–guided protocol (HPSD) vs. a control single-catheter protocol (SP).MethodsPulmonary vein isolation (PVI) with a single transseptal puncture without a multipolar mapping catheter was performed in 91 patients. Left atrial mapping was performed with the ablation catheter, only. Pacing maneuvers were used to confirm exit block. Procedural characteristics and success rates were compared using HPSD (n = 34) vs. a control (n = 57) ablation protocol. Freedom from recurrence was defined as a 1-year absence of AF episodes > 30 s, beyond the 3-month blanking period.ResultsUsing the HPSD protocol the median procedure and RF ablation time were significantly shorter compared to the SP, 84 (IQR 76–100) vs. 118 min (IQR 104–141) and 1036 (898–1184) vs. 1949s (IQR 1693–2261), respectively, p < .001 for all. First-pass PVI was achieved using the HPSD protocol in 88% and using the SP in 87% of patients, p = 1.0. No procedural complications were observed. High-sensitivity cardiac troponin levels were significantly higher in patients using the HPSD protocol compared to the SP. At 12 months follow-up, 87% patients remained free from AF with no differences between groups.ConclusionsA minimalistic, HPSD ablation index–guided PVI with a single-catheter approach is very efficient, safe, and associated with excellent clinical outcomes at 1 year.

Establishing safe, effective ablation in the diseased human ventricle: an analysis of generator impedance and electrogram attenuation

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Biosense Webster Inc Background Predictors of effective and safe lesion delivery in the human left ventricle have not been established. Generator impedance (GI) drop and electrogram (EGM) attenuation are indices which can be used as surrogates for ablation lesion parameters. Tissue pops are a complication of myocardial overheating preceded by a rise in GI and can have adverse consequences. Purpose To establish the relationships between Ablation Index (AI), Force Time Integral (FTI) and contact force with GI and EGM attenuation. To establish factors early in ablation that are predictive of a GI rise. Methods Patients undergoing ventricular tachycardia ablation were recruited. All ablations were performed with contact force sensing surround flow catheters. Electrograms were collected pre and post ablation, with GI, AI, FTI measured during. Ablations were divided into low (LVM, &amp;lt; 0.50mV), intermediate (IVM, 0.51 – 1.50mV) and normal voltage (NVM, &amp;gt; 1.50mV) based upon pre-ablation bipolar EGM amplitude. Ablations with a 5% rise in GI from maximal drop were noted and predictors of this explored. Results In 15 patients, 402 ablations were analysed. Filtered percentage GI drop correlated with AI and FTI, (p &amp;lt; 0.0005, Spearman’s ρ = 0.522 and 0.524) and reached a plateau at 763AI and 713gs, a filtered GI drop of 7.5% (Figure 1). Shallower curves occurred progressively from NVM to IVM to LVM, (p &amp;lt; 0.0005), (Figure 2) The bipolar EGM significantly attenuated with ablation, (median attenuation 0.14mV, [29.3%], p &amp;lt;0.0005), but percentage attenuation did not correlate with AI or FTI. Parameters associated with a GI rise during ablation were greater mean CF to maximum GI drop, (p = 0.002), greater initial percentage GI drop at 5 seconds, (p &amp;lt; 0.0005), power of 50W (p = 0.005), and perpendicular orientation, (p = 0.006). Percentage GI drop at 5 seconds was the best predictor of ablations with a GI rise, (AUCROC 0.773; 95% CI 0.708 – 0.838; optimal cut-off 2.44%). Mean contact force to maximum GI drop was a poor predictor of a GI rise (AUCROC 0.647; 95% CI 0.577 – 0.718, optimal cut-off 14.7g). Conclusion During left ventricular ablation, AI of 763 and FTI of 713gs should be targeted, with a lower impedance drop observed for more scarred myocardium. A GI drop of &amp;lt;2.5% at 5 seconds and contact force &amp;lt; 15g should be used to optimise ablation safety.

Characterization of high-power and very-high-power short-duration radiofrequency lesions performed with a new-generation catheter and a temperature-control ablation mode

Abstract Funding Acknowledgements Type of funding sources: None. Introduction High-power short-duration (HP-SD) and very high-power short-duration (VHP-SD) has recently emerged as an alternative ablation strategy to shorten application times while maintaining or improving the effectiveness and safety of atrial fibrillation ablation (1 - 2). Although usually performed with standard irrigated-tip catheters in a power-controlled mode, a novel dedicated catheter with a multi-thermocouple system capable of real-time temperature monitoring and optimized for temperature-controlled ablation by power and irrigation rate modulation has been developed for this scenario (3 - 4). Purpose We conducted an experimental ex-vivo study to analyse the differences between radiofrequency lesions obtained with this novel catheter (QDOT MICRO®) using HP-SD and VHP-SD. Besides, we also aim to compare them to HP-SD lesions obtained with a standard non-dedicated catheter (THERMOCOOL SMARTTOUCH®) and to conventional-powered lesions performed with either catheter. Methods 280 epicardial radiofrequency applications were performed on porcine left ventricle submerged in 37ºC saline: 40 VHP-SD (90W) with QDOT MICRO (4 sets of 10 using a contact force (CF) of 10 and 20 grams and an application time of 3 and 4 seconds); 80 HP-SD lesions (50W), 40 of them with QDOT MICRO and 40 of them with THERMOCOOL SMARTTOUCH (4 sets of 10 lesions using a CF of 10 and 20 and an ablation index (AI) of 400 and 550 with each catheter) and 160 conventional-power lesions (35 and 40W), 80 of them with QDOT MICRO and 80 of them with THERMOCOOL SMARTTOUCH (4 sets of 10 lesions using a CF of 10 and 20 and an AI of 400 and 550 for each catheter and power setting). After each application, lesions were cross-sectioned and measured. Volume vas calculated using a validated formula (5). Results In an intracatheter analysis, HP-SD lesions were bigger than VHP-SD ones, both when using parameters intended for posterior wall ablation (AI 400 in HP-SD or 3 seconds in VHP-SD), 98.1±11.7 vs 36.8±8.5 mm3, p&amp;lt;0.0001 with 10g CF, and 106.7±8.1 vs 52.3±9.8 mm3, p&amp;lt;0.0001 with 20g CF; and when using parameters intended for anterior wall ablation (AI 550 in HP-SD or 4 seconds in VHP-SD), 227.6±25.1 vs 61.0±7.8 mm3, p&amp;lt;0.0001 with 10g CF, and 186.6±23.3 vs 72.2±5.0 mm3, p&amp;lt;0.0001 with 20g CF (see figure). In an intercatheter analysis, conventional as well as HP-SD lesions were generally smaller with THERMOCOOL SMARTTOUCH than with QDOT MICRO, although less difference could be found when applying a CF of 20g instead of 10g (see figure and table). Conclusions VHP-SD lesions are smaller than HP-SD ones, which would allow for a safer and faster ablation. However, a HP-SD strategy would be preferable over VHP-SD if greater lesion volume is desirable.

Areas of minimal generator impedance drop during the index atrial fibrillation ablation correlate with pulmonary vein reconnection sites despite adopting the CLOSE protocol

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulmonary vein (PV) isolation is the cornerstone of atrial fibrillation (AF) management. However, AF recurrence is extremely common after a single procedure. The CLOSE protocol, which is the standardisation of radiofrequency catheter ablation by delivering a point-by-point lesion set defined by ablation index (AI), has demonstrated 80% freedom of AF. Yet PV reconnection is still up to 38% in these patients (1). A small decrease in generator impedance (GI), which is not part of the AI algorithm, has been associated with recovery of PV conduction. Purpose The study aimed to identify whether lesions having a poor impedance drop (PID) after wide area circumferential ablation (WACA) are associated with PV reconnection, despite adopting to the CLOSE protocol. Methods 120 consecutive patients who had both the index (i-AFA) and redo AF ablations (r-AFA) due to AF recurrence at our centre from Jan 2018 to Jun 2021 were screened. 18 patients who had WACA around PVs using high power (40 to 50W) with a minimum AI of 400, whilst adhering the CLOSE protocol during the i-AFA, and who had evidence of PV reconnection during r-AFA, were included in the study. Ones who had left atrial (LA) substrate or cryoablation were excluded. GI was measured between the skin patch and ablation catheter. CARTO® system was used to create LA electroanatomical maps (EAMs) and register ablation lesions. Each WACA around PVs was divided into eight anatomical segments (Figure). PID was defined as an impedance change of &amp;lt;8Ω, based on previous studies (2). These lesions were identified and categorised to the relevant anatomical segment in the i-AFA. Locations of the discrete ablation lesions that re-isolated PVs during the r-AFA, were used as a surrogate to denote areas of PV reconnection. These were also spatially matched to the relevant anatomical segment. Each EAM was reviewed by two electrophysiologists. Results 30 out of the 36 WACAs (83%) and on average, at least 2 segments per WACA (2.6; 95% confidence interval (CI): 2.2-3.1) had reconnected. 54% of the reconnected segments had at least one lesion with PID. Having a lesion with PID in a PV segment in the i-AFA was significantly associated with evidence of PV reconnection in the same segment in the r-AFA (odds ratio: 2.1 [95% CI: 1.3-3.6; p&amp;lt;0.01]). Right posterior/inferior (56%) and left anterior/superior (50%) PV segments were the most common areas to reconnect and these areas were also associated with a higher incidence of PID lesions in the i-AFA (94% and 67%, respectively). Conversely, 80% of segments with all lesions having an impedance drop of ≥8Ω had no PV reconnection. Conclusion Lesions with PID in the i-AFA could impact PV reconnection, despite lesion contiguity and an adequate AI. Identifying and targeting these areas of PID, in addition to the CLOSE protocol, could potentially reduce AF recurrence. Prospective studies are needed to validate this hypothesis and its safety.

Pulmonary vein isolation with high power, short duration ablation leads to shorter procedure times associated with high success rates: a Prospective Randomized Trial

Abstract Funding Acknowledgements Type of funding sources: None. Background The single procedure success rates of durable pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (AF) varies between 85 and 90 %. This prospective, randomized study investigated the efficacy of high power, short duration ablation in a temperature-controlled mode versus standard power settings in terms of single-procedure arrhythmia-free outcome, safety and procedural time. Methods and results A total number of 176 patients undergoing de-novo catheter ablation for paroxysmal AF were randomized to two different treatment arms. In group-A patients, PVI was performed with RF-energy with standard power settings of 30 Watts in a temperature-controlled mode. The ablation procedure in group B was performed with RF-energy with higher power settings of 45 Watts. In both groups the ablation was performed with ablation index (AI) and following the CLOSE protocol (Biosense Webster Thermocool STSF). A total of 88 patients were randomized into each group without significant differences in baseline characteristics. During a mean follow-up of 12 ± 4 months after a single procedure, 79 (90%) patients of group A were free of arrhythmia recurrence versus 82 (93 %) patients in group B (p=ns). With regard to the procedural data, the procedure time was significantly shorter in group B (115.35 ± 15.38 versus 96.45 ± 17.19; p&amp;lt;0.01), the flouroscopy time and dose area were also significantly lower in Group B (9.66 ± 3.86 vs 5.45 ± 2.35; 330.84 ± 150.36 vs 202.51 ± 135.23) and total ablation times were significantly shorter in group B ((Table 1). Both procedures were performed with a low number of complications, no pericardial effusion was seen in either group, in both groups two patients had a significant hematoma of the groin with the need of surgical repair. Conclusions RF-ablation with high power (45 Watts) in combination with ablation index and following the CLOSE protocol leads to shorter procedure times, a lower total ablation time and a good safety profile.

Fifty-fifty - a comparison of two 50 watts high power short duration protocols using temperature- versus power- controlled radiofrequency ablation for atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background Radiofrequency-guided catheter ablation (RFCA) is an established treatment option for atrial fibrillation (AF). New approaches applying higher than usual energy levels for shorter periods (high power short duration, HPSD) to improve lesion quality have been reported. The novel DiamondTemp (DT) catheter allows for temperature-guided high power RFCA. Data on a direct comparison of the two emerging RFCA approaches are lacking. Purpose This observational single center study aimed to compare the efficacy, safety and characteristics of the novel DT catheter to an ablation index (AI) guided 50 W high power short duration (HPSD) ablation protocol using a conventional force-sensing equipped ablation catheter with surround-flow. Methods A total number of 101 patients undergoing RFA for AF were included. 33 patients treated with the DT catheter (50 W, 9 sec), were compared to 69 consecutive patients undergoing AI-guided AF ablation (AI anterior 550; AI posterior 400) with an open-irrigated catheter adherent to a 50 W HPSD protocol. Procedural data and recurrence rates were documented. Follow-up examinations were scheduled after 3, 6 and 12 months. Results Acute procedural success was achieved in all patients (n=101, 100%). DT-guided AF ablation was associated with a significantly longer mean procedure duration (98.8±30.1min vs. 78.2±25.6, p=0.002*). PVI using the DT ablation catheter required significantly more RF applications (75.4±30.8min vs. 61.3±14.1, p=0.019*). Total RF duration was significantly lower in the DT group (792.1±311.2sec vs. 1035.5±287.2sec, p&amp;lt;0.001*) as well as fluoroscopy time (4.6±2.1min vs.5.5±2.5min, p&amp;lt;0.006*) and dose (183.8±178.1yGym2 vs. 295.8±247.5yGym2, p&amp;lt;0.013*). Procedure related mayor complications occurred in 1 patient from the DT group (acute stroke; 3%) and in no patients from the HPSD cohort. Early recurrence was reported from 4 patients treated with the DT catheter (12%) compared to 8 patients undergoing HPSD RFA (12 %) (p=1.000). Conclusion Temperature- and power- controlled AF ablation using 50 W was safe and effective. AI-guided HPSD ablation resulted in significantly shorter procedure times with significantly fewer RF applications for PVI, whereas total RF duration and fluoroscopy times were significantly higher in this cohort. Further studies are needed to confirm this initial observation.

Personalized persistent atrial fibrillation ablation guided by left atrial wall thickness: a multicenter study

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulmonary vein isolation (PVI) has been proven to be effective in treating persistent atrial fibrillation (PeAF), although long-term ablation outcomes have been significantly less satisfactory than in paroxysmal AF (1). A recent personalized PVI approach, aiming for contiguous lesions with ablation index (AI) titration according to the local left atrial wall thickness (LAWT) as per multidetector cardiac tomography (MDCT), has demonstrated to achieve an arrhythmia-free survival &amp;gt; 95% at 12 months in patients with paroxysmal AF (2). Purpose We sought to investigate the safety and clinical outcomes of this personalized PVI approach guided by LAWT in patients with PeAF. Methods Consecutive patients referred for PeAF first ablation were prospectively enrolled from three referral centers. PeAF was defined in the presence of at least one AF episode sustained beyond 7 days. LAWT three-dimensional maps were obtained from MDCT and integrated into the navigation system. LAWT was categorized into 1 mm layers and AI was titrated to the LAWT. The ablation line was personalized to avoid thicker regions (Figure 1) while encircling PV antrum. Follow-up was scheduled at 1, 3, 6, and every 12-months thereafter. Results One hundred twenty-seven patients [89 (70.6%) male, age 64 ± 10 years] were included. 68 (60.7%) patients were hypertensive, 10 (18%) patients suffered of type 2 diabetes, and mean CHA2DS2-VASc score was 2.3 ± 2.1. Mean procedure time was 61 ± 20 minutes and mean fluoroscopy time was 1.3 ± 2.2 minutes. Radiofrequency (RF) time was 9.0 ± 2.3 minutes for the right pulmonary veins with a first-pass isolation in 109 (85.8%) patients and 7.6 ± 1.9 minutes for the left pulmonary veins with first-pass in 110 (86.6%). No major complication occurred. The rate of survival free from AF recurrences at a mean follow-up of 12 ± 6 months was 82% (Figure 2). Conclusions Personalized Persistent AF ablation by wide circle PV isolation guided by LAWT, proved to be safe and highly efficient, requiring a low amount of RF delivery, procedure time, and fluoroscopy use, while obtaining a high rate of first-pass isolation and of freedom from AF recurrences.

Photoplethysmography telemonitoring during the first week after atrial fibrillation ablation: Feasibility and clinical implications

Abstract Funding Acknowledgements Type of funding sources: None. The incidence of early atrial fibrillation (AF) recurrence within the first week after AF ablation and its predictive value for late AF recurrences are unclear. TeleCheck-AF is a remote on-demand mobile health (mHealth) infrastructure, which is based on a mobile phone app using photoplethysmography (PPG) technology (Fibricheck) allowing rate and rhythm monitoring through teleconsultations. The feasibility and clinical implications of PPG telemonitoring specifically during the first week after atrial fibrillation ablation is unknown. Methods Within the TeleCheck-AF project, the Medical University offered a total of 382 consecutive patients undergoing AF ablation (between June 1st 2020 and December 15th 2021) photoplethysmography (PPG) telemonitoring with "FibriCheck" during the first week after the ablation procedure. Patients received a QR code for activation of the software on their smartphone and were connected to the clinician’s telemedicine portal. They were instructed to perform rhythm monitoring three times per day and in case of symptoms. Clinicians assessed the tracings and contacted the patients if therapeutic steps were indicated. Results In total, 119 patients (31%) agreed to perform telemonitoring after ablation. Patients undergoing telemonitoring were younger compared to those who refused participation (58±10years vs. 62±10years, p&amp;lt;0.001). 34% were female, median CHA2DS2-VASc-Score was 1 (0-6). 62% of patients had paroxysmal AF and 37% had persistent AF. One of four patients (24%) had already undergone previous ablations. Most index ablations were radiofrequency ablations (89%; 7% cryo; 4% pulsed field ablation). Median follow up duration was 281 (16-620) days. 27% of patients had tracings suggestive of AF in the week following the index ablation. Telemonitoring resulted in clinical interventions ins 24% of patients: amiodarone was started in 8%, class I antiarrhythmic drugs were up titrated in 7%, cardioversion was scheduled in 5%, antiarrhythmic drugs were reduced due to symptomatic bradycardia in 3% of patients. During follow-up, 22% of patients had ECG-documented AF recurrences. PPG recordings suggestive of AF in the week after ablation were predictive of late recurrences (p&amp;lt;0.001). Conclusion Rhythm monitoring with a PPG-based mHealth application was feasible and often resulted in clinical interventions. Due to its high availability, PPG-based follow-up actively involving patients after AF ablation may close a diagnostic and prognostic gap and increase active patient-involvement. Figure 1: Schematic overview of the telemonitoring process. After the ablation, the patient measures PPGs for one week, dashboard view for clinician shows regular rhythm (green, atrial fibrillation (red) and unclear tracings (blue).

Endocardial ablation of ventricular tachycardia ablation in arrhythmogenic right ventricular cardiomyopathy aiming epicardial late potential abolition

Abstract Funding Acknowledgements Type of funding sources: None. Background Catheter ablation is frequently needed to treat ventricular tachycardia (VT) in ARVC patients. Ablation aiming non-inducibility (NI) and late potential (LP) abolition has been shown to be effective1. Simultaneous endo-epicardial mapping demonstrate epicardial involvement in most VT2. However epicardial fat and vicinity of coronary artery may prevent effective epicardial ablation. Aims (a) evaluate endocardial-only ablation guided by epicardial late-potential recording (EA-ELP) to achieve LP abolition (LPA) and NI; (b) measure ablation-index(AI) values allowing epicardial LP suppression by endocardial ablation, as a surrogate for transmurality. Methods From 2019 to 2021 the authors (XW, EG) evaluated EA-ELP in ARVC patients patient referred for ablation. Our ablation protocol was previously described3. Endo and epicardial voltage mapping of the right ventricle (RV) were performed in sinus rhythm using 0.5-1.5 mV threshlods for endocardial scar and 0.5-1 mV for the epicardial. All LP were manually tagged. Programmed ventricular stimulation (PVS) was performed till S4 from the RV apex and other sites, all inducible tolerated VT were mapped. Endocardial ablation was performed with an irrigated tip catheter positioned in front of epi-LP recorded by a multi-electrode catheter aiming to eliminate or delay epi-LP as a surrogate for transmurality. For each lesion fulfilling the «transmurality criteria», the AI values were recorded. Remap was performed to validate LPA and NI was tested. Patient follow-up (FU) rely on telemonitoring in ICD-carriers and holter/exercise test for the others. Results 11 patients were enrolled (9M/2F, mean age 45 years), 9 for VT recurrence (3 redo) and 2 for de novo VT. The median ICD therapy before ablation was 5/patient (mean 1.7). The clinical VT originated from the RV outflow tract (RVOT) in 5 patients, peritricuspid (PT) in 2, RV free wall (RFW) in 4. Substrate were more extended in the epicardium compared to the endocardium: epi-LP and scar surfaces were 42.5 cm2/118 cm2 versus 24.5 cm2/25.5 cm2 for the endocardium. In one patient, additional epicardial lesion was necessary to achieve LPA. The mean ablation duration was 3377 s. Remap showed LPA in all patients and PVS was negative in all (not tested in one due to hemodynamic instability). One patient presented retrosternal hematoma after ablation with spontaneous favorable outcome. Endocardial AI values allowing epi-LP abolition were 595 for the inferior wall, 625 in the RVOT, 604 for PT and 639 for RFW. During a mean FU of 12 months (median 16.5 mths), only one patient had VT recurrence. Conclusion Based on this case-series, EA-ELP appeared as a safe and effective method to treat VT in ARVC. EA-ELP ablation allowed VT suppression in 91 % of patients after an mean FU of 12 mths. The RV endocardial AI needed to suppress epi-LP ranged was between 595-639 and could be used as surrogate for transmurality in ARVC.

Long term success of cavotricuspid isthmus ablation guided by the ablation index: results of the FLAI registry

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Cavotricuspid isthmus ablation (CTIA) is an effective treatment for typical atrial flutter (AFL) with a recurrence rate of about 10%. A prospective multicentric registry (FLAI registry) has recently shown that a protocol including ‘point by point’ CTI ablation targeting an a quality lesion marker (Ablation Index AI) ≥ 500 and a maximum inter-lesion distance (ILD) measurement of ≤6 mm allowed an acute success rate of 98.3%. In this study, we aimed to describe the incidence and predictors of recurrence of both AFL and atrial fibrillation (AF) in a long-term follow-up of the patients enrolled in the FLAI registry. Methods The FLAI registry was a multicentric non-randomized study that enrolled 412 consecutive patients (mean age 64.9±9.8; 72.1% males; 27.7% with structural heart disease). Patients with typical AFL underwent an AI-guided cavotricuspid isthmus ablation. The procedures targeted an AI of 500 and an ILD measurement of ≤ 6mm. The primary endpoints were CTI ‘first pass’ block and persistent block after a 20-minute waiting period. The CTI bidirectional "first pass block" was reached in 355 patients (88.3%), whereas CTI block at the end of the waiting period was achieved in 405 patients (98.3%). No complications were reported. The mean time of follow-up was 21±4.24 months and it was available for 397 patients. The FU included outpatient clinical evaluation, ECG and 24-h Holter ECG at three, six- and 12-months post-ablation, followed by an annual clinical evaluation and ECG. Documented ECG Atrial fibrillation events, in follow up, were also included in the data set. Results Atrial flutter recurrence: 22 AFL events were observed (5.5%) at 34 months. According to the Kaplan Meier analysis, the growth of recurrence rate was constant between 6 and 12 months, after 19 months recurrences were unlikely. At the univariate analysis predictors of AFL recurrence were: absence of bidirectional block after the waiting time period (p= 0,001); failure of the CTIA index procedure (p=&amp;lt;0,0005); ablation line lengths &amp;gt; 32 mm (p=0.,018), number of automatic ablation lesion tags (VISITAG) &amp;gt; 20 (p=0,.005) and At the increathe reported numbers of ‘g"gap’" in the ablation line lengths: the more the gaps increase the more the probability of AFL recurrence in FU increases (p=0.,037). In the Multivariate aAnalysis, the independent predictors of AFL recurrence were: the procedural success and the number of VISITAG (OR =1.062) Atrial fibrillation recurrence: 45 patients developed atrial fibrillation after CTI ablation (11.3%). In the multivariate analysis, the major independent predictor was a documented pre-procedural Afib and the risk increases with the younger age (&amp;lt; 53 yo). Conclusions The FLAI protocol is safe, reproducible and effective in the follow-up, with a long term success of 94,5%. The reported incidence of atrial fibrillation in FU was 11,3%

Durability of pulmonary vein isolation following cryoballoon ablation: lessons from a large series of repeat ablation procedures

Abstract Funding Acknowledgements Type of funding sources: None. Background The cryoballoon technology has been widely proven to be effective in achieving acute pulmonary vein (PV) isolation and favorable clinical outcome. To date, little information is still available about occurrence of late PV reconnection after cryoballoon ablation. Purpose To assess the rate of durable PV isolation following cryoballoon ablation of atrial fibrillation in the setting of repeat procedures. Methods and Results A total of 154 consecutive patients (90 male, 58.4%; mean age 60.6±12.6 years) underwent a repeat procedure, after a mean 21.5±12.4 months (median 14 months), after index ablation using the 28-mm second-generation cryoballoon. All repeat ablations were performed using a 3-dimensional electro-anatomical mapping system. Among all 590 PVs, including 26 left common ostiums (LCOs), 99 (16.8%) showed a PV reconnection in 86 patients (1.15 per patient). Persistent PV isolation could be documented in 491 of 590 PVs (83.2%). In 68 of 154 patients (44%), all PVs were electrically isolated. In the multivariable analysis, balloon nadir temperature (p&amp;lt;0.01) and time to PV isolation (P=0.02) independently predicted late PV reconnection. Conclusions The rate of late PV reconnection after second-generation cryoballoon ablation was low (1.15 PVs/patient). Globally, the rate of durable PV isolation assessed during repeat procedures was 83.2%. The balloon nadir temperature and faster time to isolation were independently associated with durable PV isolation.

Amplitude of fibrillatory wave correlates with long-term maintenance of sinus rhythm after ablation in persistent atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Commission for Technology and Innovation (CTI), Switzerland Background Amplitude of fibrillatory wave (fWA) on surface ECG is regarded as a predictor of ablation outcome for atrial fibrillation (AF). Purpose We sought to investigate whether fWA and its changes during ablation predicts long-term maintenance of sinus rhythm (SR) after wide circumferential isolation of pulmonary veins (WPVI) in persistent AF (peAF). Methods 41 patients (63±10 y, sustained AF 11±7 months) underwent a de-novo WPVI. A second WPVI was performed in patients with recurrent AF in order to provide complete PV disconnection. We defined "success" as patients who remained in SR after one or two procedures, and "failure" otherwise. 60-sec ECG signals devoid of QRST waves were recorded during the index ablation at baseline and at the end of ablation (end_WPVI, before cardioversion or conversion of AF into SR). fWA was computed on leads V1 and V6b (placed on the pts’ back) as the average difference between the upper and lower envelope of atrial ECG signals. Results Over a mean follow-up of 33±9 months, 30 patients remained free from AF (success group), while 11 patients had AF recurrence after 2 WPVIs (failure group). The clinical characteristics (e.g. age, body mass index, left atrial volume or duration in sustained AF) were similar between groups (p &amp;gt; 0.05). The success group displayed significantly higher fWA values at baseline and end_WPVI than that of the failure group (p&amp;lt;0.05, Panel A and B). No significant difference was found between baseline fWA values and those measured at end_WPVI (p &amp;gt; 0.05). Conclusion As fWA is independent of PVs contribution, it is a marker of atrial body remodelling. Low fWA values identify patients with peAF unresponsive to WPVI.

Strategies for repeat ablation for atrial fibrillation: a multicentre comparison of non-pulmonary vein versus pulmonary vein target ablation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Approximately 18% of patients with atrial fibrillation (AF) undergo a repeat ablation within 12 months after their index ablation. Despite the high prevalence, comparative studies on non-pulmonary vein (PV) target strategies in repeat AF ablation are scarce. Purpose: This study aims to describe 12 months efficacy of non-PV and PV target ablations as a repeat ablation strategy. Methods A multicentre retrospective, descriptive study was conducted with data of 280 patients who underwent repeat AF ablation. Ablation strategy for repeat ablation was at the operators’ discretion. Non-PV target ablation (n=140) included posterior wall isolation, mitral line, roofline and/or complex fractionated atrial electrogram ablation. PV target ablation (n=140), included re-isolation and/or wide atrium circumferential ablation. Patients’ demographics and rhythm outcomes during 12-months follow-up were analysed. Results: Overall, the mean age was 63 ± 9 years, 64% were male, and body mass index was 27.1 ± 4.2. Patients undergoing non-PV target ablation had more frequently persistent AF (47.9% vs 14.3%, p &amp;lt; 0.001), and had a higher CHA2DS2 VASc (2.0 vs 1.3, p &amp;lt; 0.001). At 12 months, more atrial tachyarrhythmias were observed in the non-PV target group (48.6%) compared to the PV target group (29.3%, p=0.001). Similarly, a significantly higher AF and atrial tachycardia (AT) recurrence rate was observed after non-PV target ablation compared to PV target ablation (36.4% versus 22.1% and 22.9% versus 10.7%). After adjusting for several associated covariates, a significantly higher AT recurrence risk remained in the non-PV target group (adjusted OR 2.19 95% CI 1.18 – 4.42, p = 0.023) (Figure 1C). Sensitivity analysis was performed with inverse propensity weighting to assess the robustness of the multivariate model and demonstrated comparable outcomes. Both groups significantly de-escalated anti-arrhythmic drug use, de-escalation was more profound after PV target ablation. Patients with isolated PVs during non-PV target ablation had a significantly higher risk for AF recurrence than those with reconnected PVs (Figure 1B). Conclusion: Compared to PV target ablation, non-PV target repeat ablation did not improve outcomes after 12 months and was independently associated with a higher risk for AT recurrences.

Atypical atrial flutter in patients after cardiac surgery

Abstract Funding Acknowledgements Type of funding sources: None. Background Atypical atrial flutter (AFL) is often associated with cardiac surgery or extensive catheter ablation (CA) for the treatment of atrial fibrillation (AF) [1-2]. Therefore, the increase in the number of cardiac surgery procedures leads to the development of substrates for atypical AFL onset. Incisions after cardiac surgery are common substrates for macro re-entry tachycardia and one patient can suffer from several macro re-entry tachycardia mechanisms. Atrial flutter in this category of patients lead to heart failure. Objective The aim of our study was to access the effectiveness and safety of catheter ablation of atypical atrial flutter in patients after cardiac surgery. Methods 107 adult patients with AFL after cardiac surgery and catheter ablation were included in a single-center prospective study. The patient’s mean age was 57.8±11.1 years with the prevalence of male (56%). BMI was 27,8±5 kg/m 2. All patients underwent radiofrequency ablation (RFA) of atypical AFL with 3D navigation system Carto3 using the CLOSE protocol. The patients were discharged safely and were monitored for 12 months. Results According to basic characteristics of patients cardiac surgery performed in 19.6% for CABG, in 9.3% for congenital heart disease and in 58.9% for valvular heart diseases. RFA for pulmonary veins isolation (PVI) for AF was performed in 15.9% and cryoballoon isolation of PVI in 19.6%. The onset of atrial events after incision or catheter ablation was 12 (Q1-14; Q3-25) months. In 8.4% of patients, ejection fraction was less than 40%. The mean RFA time was 110,8±10,4 min, mean fluoroscopy time 2.2 min. There were two re-entry mechanisms in 22.4% of patients, three and more re-entry mechanisms in 8.4% of patients. During 12 months monitoring after RFA in 2 (1.9%) patients registered AFL and in 8 (7.5%) of patients noticed non-sustained palpitations. Conclusions RFA of AFL with the use of ablation index and CLOSE protocol lead to the high effect and safety in patients after cardiac surgery. AFL is most frequent in patients after valvular heart surgery and usually occurs 12 months after the surgery.