Catheter Ablation Of Atrial Tachycardia Research Articles

Charge density mapping demonstrates superiority in catheter ablation of post-surgical atrial tachycardias.

Atrial tachycardia (AT) frequently occurs after cardiac surgery or surgical ablation procedures. The novel charge density-based mapping system (CDM) provides global chamber mapping and can detect crucial pathways of conduction; therefore, it has potential added value in catheter ablation (CA) of post-surgical ATs. We aimed to test the hypothesis that CDM-guided CA procedures are safe, feasible, and may improve outcome compared to conventional sequential 3D mapping (CARTO)-based CA. Consecutive patients undergoing CA for post-surgical AT guided by CDM or CARTO were enrolled. Procedural safety and efficiency were analyzed. Acute success, one-year outcome was assessed. A total of 35 patients (mean age 60.8 ± 10.6 years, 42.9% female) underwent CA of AT using CDM (n = 20) and CARTO (n = 15). A total of 61 ATs were mapped (35 in CDM and 26 in CARTO group). Four patients had focal ATs, 22 macro re-entrant, and 8 patients had ATs with both mechanisms. No differences were found in procedural complication (CDM 3 vs. CARTO 1 patient, p = 0.61). There were no differences in procedure duration (185.9 vs. 147.9 min, p = 0.09), fluoroscopy dose (165.0 vs. 155.0 mGy, p = 0.31), RF application number (28.0 vs. 18.0, p = 0.17) or duration (1,251.5 vs. 1,060.0 s, p = 0.54). Acute success was 95.0% in CDM and 73.3% in CARTO group (p = 0.14). Cumulative AT recurrence rates were lower in CDM group compared to CARTO group (10.0% vs. 46.7%, p = 0.02). The CDM system is feasible. Our data suggest that patients treated with CDM-guided CA developed fewer AT recurrences as compared to CARTO-guided procedures.

Catheter ablation for focal atrial tachycardias during pregnancy: A systematic review

ObjectivePregnancy can trigger maternal tachycardias, and the onset of recurrent or incessant focal atrial tachycardia (AT) can lead to tachycardia-induced cardiomyopathy. Medical interventions are commonly employed, but they carry potential fetal and maternal risks. Catheter ablation (CA), particularly with non-fluoroscopic navigation systems, may be considered as an alternative. This systematic review aims to explore the feasibility and outcomes of CA for focal AT during pregnancy. MethodsA thorough literature search was conducted until September 30th, 2023, on PubMed, Embase, and Cochrane databases. Included articles described maternal focal ATs diagnosed through electrophysiological studies and treated with CA. Data derived from these studies were organized into tables and subsequently analyzed. ResultsOut of 278 papers reviewed, 15 articles involving 24 patients were retrieved. CA, utilizing radiofrequency energy achieved acute success in 95.8% of cases. Sixteen patients (66.7%) underwent complete fluoroless procedures, with two adverse events directly related to the procedure reported. Long-term follow-up revealed minimal AT recurrences, with a 0.06% arrhythmia burden in one case. ConclusionFocal ATs during pregnancy can be incessant and refractory to medical intervention, precipitating an acute decline in left ventricular ejection fraction. In this setting, CA emerges as an efficacious treatment modality, particularly in cases of tachycardia-induced cardiomyopathies. Whenever feasible, it is advisable to perform these procedures with minimal or no fluoroscopy guidance. Larger studies are needed to establish the safety and the efficacy of CA for focal ATs during pregnancy, as current research consists of case reports or small case series.

Clinical and electrophysiological characteristics and long term outcomes of catheter ablation for right and left atrial tachycardias

Abstract Background Atrial tachycardias (AT) are complex supraventricular tachycardias which are refractory to antiarrhythmic drugs that require catheter ablation. Purpose In this trial, we aimed to evaulate the outcomes of catheter ablation in patients with symptomatic atrial tachycardia, define the acute procedural success and the recurrence rates in long-term follow-up and determine the clinical and electrophysiological features that affect these outcomes. Methods A total of 666 [mean age: 55 ±16, gender: 344 (51.7%) female] symptomatic patients with AT were enrolled. Prior catheter or surgical ablation history for ATa was present in 199 (29.9%) and 18 (2.7%) of these patients, respectively. Activation mapping was performed during tachycardia in all patients as well as entrainment mapping when needed. Voltage mapping were performed in sinus rhythm in both atriums, late potential mapping was also performed in some patients. Low voltage areas and signals with continuous-fragmented morphology were tagged. Results Macroreentry was the primary mechanism in right and left atrium (70.2% and 52.8%, respectively). Cavotricuspid isthmus (CTI) dependent macroreentry was the most frequent mechanism in right ATs and perimitral reentry and roof-dependent macroreentry were the most common mechanisms in left ATs. A total of 59 (7.5%) complications were observed in 780 procedures.(2.1% major and 5.5% minor) Acute procedural success was 95.9%. Freedom from ATa was 72.8 % during a mean follow-up of 39±23 months. Freedom from ATa after index procedure was 82.3% at 12 months and 75.9 % at 24 months. After multiple procedures, freedom from ATa was 90% at 12 months and 86% at 24 months during the follow-up. In multivariate Cox regression analysis, atrial fibrillation (AF) [(HR) 2.43, 95% c(CI) 1.78-3.30; p<0.001] , history of cardiac surgery [(HR) 1.68, 95% c(CI) 1.22-2.30; p=0.001] and moderate to severe tricuspid regurgitation [(HR) 1.47, 95% c(CI) 1.08-2.01; p=0.014] were significant predictors of ATa recurrence. Conclusion Our findings demonstrated that tailored catheter ablation of ATs especially guided by high density mapping has a high acute success rate and favourable long-term outcomes in patients with symptomatic AT episodes.

Evaluating left atrial wall thickness: a new frontier in predicting atrial scar and reentrant tachycardia

Abstract Background and Objective Reentrant atrial tachycardias (AT) are commonly observed in patients with atrial scar. These scars form a substrate in the atrium, characterized by areas of slow conduction, crucial for initiating reentrant cycles. During these cycles, zones of slow conduction often act as critical isthmuses (CI), becoming prime targets for ablation. Late potential mapping is a technique used to identify these slow conduction zones. Moreover, recent advancements in imaging software now allow for the precise measurement of myocardial wall thickness, aiding in the identification of thin myocardial areas that could potentially have the CI of AT. Methods We conducted a retrospective study of patients who underwent catheter ablation for AT. The study focused on patients who either presented with AT or in whom it was induced and who had undergone late potential mapping of the left atrium. To identify deceleration zones (DZ), we created voltage maps and isochronal late activation maps (ILAM) during sinus or paced rhythm. Electrograms exhibiting a continuous-fragmented morphology were explicitly marked. Upon induction of AT, activation mapping was employed to pinpoint the CI of the tachycardia circuit. Additionally, the thickness of the left atrial (LA) wall and LA volume were measured using ADAS3D software. Results A total of 39 patients, with 25 (65.1%) being female, were enrolled in the study. The mean age of the participants was 62.5 ± 9.5 years. The average volume of the left atrium was measured at 124.8 ± 35.5 mL, and the mean thickness of the LA wall was 1.58 ± 0.2 mm. In most patients (16, 41.0%), the septal wall was the thinnest part of the left atrium. However, significant thinning of the LA wall was observed predominantly on the anterior wall in 29 patients (74.2%) and on the LA roof in 18 patients (46.2%). The sensitivity and positive predictive value (PPV) of thinning in the LA anterior wall in detecting late potentials were 74.1% and 68.9%, respectively. For detecting critical isthmuses, these values were 76.9% (sensitivity) and 66.7% (PPV). Regarding the LA roof, the diagnostic value for thinning in detecting late potentials and critical isthmuses showed a sensitivity of 57.1% and 57.9%, respectively, and a PPV of 57.1% and 52.4%, respectively. Conclusion Evaluating LA thickness represents a novel approach that can potentially identify LA scars and late potentials before the procedure, particularly in the LA anterior wall. While the observed positive predictive values are acceptable, the negative predictive values and specificity are relatively low. Future advancements in imaging software, along with the development of standardized cardiac computed tomography protocols, can potentially enhance these outcomes. Consequently, preprocedural computed tomography could become increasingly significant in managing and treating AF and AT beyond LA anatomy evaluation.TablesLeft Atrial Wall Thickness

Successful catheter ablation of atrial tachycardia initiated with orthodromic capture of superior vena cava potentials.

Acase of successful catheter ablation of paroxysmal atrial fibrillation and atrial tachycardia is reported. After pulmonary vein isolation, atrial tachycardia was induced by the use of isoproterenol and burst pacing from the catheter in the right atrium. An attempt was made to create athree-dimensional (3D) map of the atrial tachycardia, but the atrial tachycardia was terminated in the middle of the mapping. The 3D map was insufficient but indicated that the superior vena cava was involved in the circuit. When the intracardiac electrograms were reviewed, it was found that the atrial tachycardia was initiated with orthodromic capture of superior vena cava potentials and it was considered that the atrial tachycardia involved the superior vena cava-right atrium junction. Accordingly, superior vena cava isolation was performed. After that, atrial fibrillation and atrial tachycardias were not induced by the use of isoproterenol and burst pacing. In this case, an intracardiac electrogram at the time of induction of the tachycardia was helpful for understanding the circuit of the tachycardia.

Incidence of Atrial Fibrillation After Radiofrequency Catheter Ablation for Atrial Tachycardia in Congenital Heart Disease

BackgroundAtrial tachycardia (AT) and atrial fibrillation (AF) coexist in 30% of congenital heart disease (CHD) patients. Successful atrial tachycardia catheter ablation (ATCA) might prevent AF. Data on new-onset AF after ATCA in CHD is scarce. ObjectivesThis study aimed to evaluate the incidence of new-onset AF after ATCA and to assess clinical characteristics associated with new-onset AF after ATCA in CHD. MethodsCHD patients referred for ATCA to 3 European centers were included. New occurrence of AF was defined as electrocardiographic documentation of AF after any ATCA procedure in patients without history of AF. ResultsIn 277 CHD patients (median age 37 years [Q1, Q3: 23, 49 years], 58% men, 59 [21%] simple, 111 [40%] moderate, and 107 [39%] complex CHD), AF occurred in 25 patients (9%) a median of 8 months (Q1, Q3: 4, 27 months) after ATCA. New-onset AF was persistent in the majority of the patients (17 of 25 [63%]). Patients with new-onset AF were older (44 years [Q1, Q3: 29, 55 years] vs 36 years [Q1, Q3: 23, 49 years]; P = 0.009) and more frequently had simple CHD (13 of 25 [52%] vs 46 of 252 [18%], respectively; P < 0.0001). Acute ATCA success rates were similar in patients with and without AF (52% vs 48%; P = 0.429). Simple CHD was an independent predictor of new-onset AF during follow-up. ConclusionsIn our large cohort of patients with congenital heart disease, new-onset AF after ablation for AT occurred in only 9% of the patients. AF occurred without AT recurrence and was persistent in the majority of patients.

Electrophysiologic mechanism and ablation strategy for macroreentrant biatrial tachycardias after Cox-maze procedures

BackgroundDifferent types of recurrent atrial tachycardia (AT) after Cox-maze procedures have been reported, whereas biatrial tachycardia (BiAT) has not been systematically analyzed. ObjectiveIn this study, we retrospectively investigated the electrophysiologic characteristics of BiAT after Cox-maze procedures by use of an ultrahigh-density mapping system. MethodsOf a consecutive 76 patients who underwent catheter ablation of AT after Cox-maze procedures, 12 BiATs were identified. High-density activation mapping was performed in both the left atrium and right atrium in combination with entrainment pacing to confirm the circuit. ResultsWe classified these BiATs into 2 groups. In group 1 (7 patients), the bidirectional block of maze linear lesions to prevent the macroreentrant AT was achieved; the posterior interatrial connections were involved in the circuit. In group 2 (5 patients), the bidirectional block of maze linear lesions was not blocked, and the most common gap was located at the end of the linear lesion near the annulus. In group 1, all the ATs were terminated by targeting the corresponding left atrium end of the posterior interatrial connections. In group 2, the ATs were terminated by targeting the gap near the annulus. ConclusionThe optimal ablation strategy for BiATs after the maze procedure should be based on detailed demonstration of the circuit by high-density mapping.

Remote magnetic navigation catheter ablation for atrial tachycardia in a patient with d-transposition of the great arteries, atrial switch, and a mechanical valve in the tricuspid position.

Remote magnetic navigation catheter ablation for atrial tachycardia in a patient with d-transposition of the great arteries, atrial switch, and a mechanical valve in the tricuspid position.

Prognostic implications of baseline rhythm during catheter ablation for atrial tachycardia.

Atrial tachycardias (AT) occurring in patients after previous atrial fibrillation (AF) ablation are increasingly observed in clinical practice. Catheter ablation is the treatment of choice but an optimal workflow to improve patient outcome has not been defined. The purpose of this study was to assess procedural and clinical outcome depending on baseline rhythm at the beginning of AT ablation. A total of 380 patients (69 (61-75) years, 56.6% male) who underwent catheter ablation for consecutive AT after previous AF ablation were studied. At the beginning of the procedure, 140 patients (36.8%) presented in sinus rhythm (SR), 208 (54.7%) with AT and 32 (8.4%) with AF. Patients in SR or with AT underwent shorter procedures (173 (132-213) minutes vs. 161 (120-203) minutes vs. 226 (154-249) minutes; p = 0.002) with more frequent termination to SR (87.9% vs. 81.3% vs. 56.3%; p < 0.001) than patients with AF. Acute procedural success did not differ between patients in SR or with AT but was higher compared to those with AF (96.4% vs. 97.1% vs. 87.5%; p = 0.033). During a follow-up of 290 (181-680) days, patients in baseline SR experienced arrhythmia recurrences less often (36.4% vs. 49.5% vs. 68.8%; p = 0.002) than patients with AT or AF. Baseline rhythm during AT ablation predicts procedural and clinical outcome. Whereas acute procedural success does not differ between patients in SR or with AT, patients presenting in SR have a more favorable mid-term success rate.

Baseline rhythm during catheter ablation for atrial tachycardia predicts procedural and clinical outcome

Abstract Funding Acknowledgements Type of funding sources: None. Background Atrial tachycardias (AT) occurring after previous ablation in patients with a history of atrial fibrillation (AF) are increasingly observed in clinical practice. Catheter ablation is the treatment of choice but an optimal workflow to improve patient outcome has not been defined. The prognostic implications of baseline rhythm at the beginning of AT ablation are unknown. Purpose The aim of this study was to assess procedural and clinical outcome depending on baseline rhythm during AT ablation. Methods A total of 380 patients with a history of AF who underwent catheter ablation for consecutive AT after previous ablation were analysed. Results In our study population (69 (61–75) years, 56.6% male), 140 patients (36.8%) presented in baseline sinus rhythm (SR), 208 (54.7%) with AT and 32 (8.4%) with AF at the beginning of the procedure. Patients in SR or with AT underwent shorter procedures (SR: 173 (132–213) minutes vs. AT: 161 (120–203) minutes vs. AF: 226 (154–249) minutes; P=0.002) with more frequent termination to SR (SR: 87.9% vs. AT: 81.3% vs. AF: 56.3%; P&amp;lt;0.001) than patients with AF. Periprocedural AT cycle length was longer in patients presenting in SR than in those with AT or AF (SR: 320 (265–370) ms vs. AT: 270 (240–310) ms vs. AF: 245 (193–278) ms; P&amp;lt;0.001). Acute procedural success did not differ between patients in SR or with AT but was higher compared to those with AF (SR: 96.4% vs. AT: 97.1% vs. AF: 87.5%; P=0.033). During a median follow-up of 290 (181–680) days, patients in baseline SR developed arrhythmia recurrences less often (SR: 36.4% vs. AT: 49.5% vs. AF: 68.8%; P=0.002) compared to patients with AT or AF. Conclusions Baseline rhythm during AT ablation predicts procedural and clinical outcome. Whereas acute procedural success does not differ between patients in SR or with AT, patients presenting in SR have a more favourable mid-term success rate. Restoration of SR prior to ablation might improve long-term outcome by reducing the risk for recurrent arrhythmia.

Automated three-dimensional activation versus conventional mapping for catheter ablation of atrial tachycardia – A prospective randomized trial

BackgroundThe automated NavX Ensite Precision latency-map (LM) algorithm aims to identify atrial tachycardia (AT) mechanisms. However, data on a direct comparison of this algorithm with conventional mapping are scarce. MethodsPatients scheduled for AT ablation were randomized to mapping with the LM- algorithm (LM group) or to conventional mapping (conventional only group: ConvO), using entrainment and local activation mapping techniques. Several outcomes were exploratively analyzed. Primary endpoint was intraprocedural AT Termination. If AT termination with only automated 3D-Mapping failed, additional conventional methods were applied (conversion). ResultsA total of 63 patients (mean 67 years, 34 % female) were enrolled. In the LM group (n = 31), the correct AT mechanism was identified in14 patients (45 %) using the algorithm alone compared to 30 patients (94 %) with conventional methods. Time to termination of the first AT was not different between groups (LM group 34 ± 20 vs. ConvO 43.1 ± 28.3 min; p = 0.2). However, when AT termination did not occur with LM algorithm, time to termination prolonged significantly (65 ± 35 min; p = 0.01). After applying conventional methods (conversion), procedural termination rates did not differ between LM group (90 %) vs. ConvO (94 %) (p = 0.3). During a follow-up time of 20 ± 9 months, no differences were observed in clinical outcomes. ConclusionIn this small prospective, randomized study, theuse of the LM algorithm alone may lead to AT termination, but less accurate than conventional methods.

Non-invasive electrocardiographic imaging for the characterization of complex atrial tachyarrhythmias

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This work was supported by the European Union NextGenerationEU/PRTR. Background – The non-invasive characterization of complex atrial tachyarrhythmias, including atrial flutter (AFL) and focal atrial tachycardia (AT) is challenging. Conventional 12-lead electrocardiogram (ECG) faces several limitations. Planning a precise and preprocedural strategy for complex tachyarrhythmias catheter ablation (CA) is not easy. Purpose To evaluate the diagnostic capacity of a novel electrocardiographic imaging (ECGI) system that does not require previous CT/MRI thoracic imaging. Methods – 42 patients (27 males, CHA2DS2-VASc score 2±1, LVEF 54.5 ± 11.0 % and LA area 31.3 ± 7.0 cm2) undergoing CA for focal AT or AFL were prospectively included in the study. A preprocedural ECGI was managed based on a 64-electrode vest, a torso reconstruction using a 3D real-time acquisition camera, and an artificial intelligence-based method to estimate the patient atrial geometry. The differential diagnostic capacities of non-invasive 12-lead ECG and ECGI were assessed compared with endocavity electroanatomical mapping (EAM) regarding three endpoints: 1) the identification of the involved atrial cavity, 2) the mechanism (focal/micro-reentry or macro-reentry), and (3) the ablation target site defined as the area where the earliest activation was located for focal/micro re-entrant arrhythmias, and the precise anatomical pathway for macro re-entrant tachyarrhythmias. Regarding the ECG, the three endpoints were assessed based on validated algorithms by 2 different observers blinded from the diagnosis. Results – 48 atrial tachyarrhythmias of which 59.5% occurred in the context of a history of CA were evaluated. The non-invasive characterization of complex atrial arrhythmias using this novel ECGI system was possible in 94% of the cases (Figure A): directly for 36 arrhythmias and after decreasing ventricular response using vagal maneuvers for 9. ECGI obtained global accuracy to identify the involved atrial cavity of 91.7%, the mechanism of 89.6%, and the ablation target of 83.3%. In challenging cases, such as in patients with history of CA for AF (n = 27) and in patients without a final diagnosis of counterclockwise typical AFL (n=38) the diagnosis capacity of ECGI is consistent compared to the whole study population. The ECGI diagnostic capacity significantly outclassed the ECG one regarding the identification of the involved cavity (p&amp;lt;0.001), the mechanism (p&amp;lt;0.05), and the ablation target (p&amp;lt;0.001). ECGI was able to prevent the totality of unnecessary transseptal punctures (n=7), representing 28% of the overall punctures. Conclusions (Figure B) – This novel non-invasive ECGI system that does not require CT/MRI thoracic imaging accurately characterizes complex atrial tachyarrhythmia and outclasses ECG, the current noninvasive diagnostic tool of reference.

PE-452787-3 INITIAL EXPERIENCE OF PULSED FIELD ABLATION OF ATRIAL FIBRILLATION AND ATRIAL TACHYCARDIA IN ADULT PATIENTS WITH CONGENITAL HEART DISEASE

Prevalence of atrial tachycardias (AT) and atrial fibrillation (AF) is increasing in adult patients with congenital heart disease (CHD) significantly contributing to morbidity. Catheter ablation of AT and AF in the adult CHD population is challenging and recurrence is significant. Pulsed field ablation (PFA) is a new, non-thermal energy source for catheter ablation of AF. Due to its inherent properties of creating effective ablation lesions without permanent affection of non-myocardial tissue, it is attractive for the use in the adult CHD population. To date, its use in the adult CHD population has not been reported. This study describes initial experience of PFA of AT and AF in adult CHD patients. Prospective enrollment of adult CHD patients with a history of recurrent AT/AF, who had prior radiofrequency (RFA)/cryoenergy (Cryo) ablation of AT/AF. A high-density map using a 3D mapping system (EnSite™ Precision; Abbott) in conjunction with a high-density catheter (Advisor™ HD Grid; Abbott) was performed prior and after PFA. PFA was performed using the FARAWAVE™ ablation catheter (Boston Scientific) and applying repeated 2 kV pulses (2.5 s each) to the respective substrate. Procedural success was defined as complete substrate ablation (residual atrial electrograms < 0.05 mV on voltage map). Four adult CHD patients with recurrent AT/AF despite repeated previous RFA/cryoablation were enrolled. 2/4 had interrupted inferior V. cava and a transhepatic access was used to get access to the left atrium. PFA of all pulmonary vein ostia and the left atrial posterior wall was performed in 3 subjects. Additional PFA of a septal low voltage area was achieved in one of these patients. In the fourth patient with Ebstein’s anomaly, PFA of the cavotricuspid isthmus (CTI) and of a conduction gap within the crista terminalis was performed. Complete procedural success was achieved in all patients. Transient, fully reversible spasm of the right coronary artery without ECG changes occurred after PFA within the CTI. No recurrence of AT/AF was observed during follow-up of 5 months. Herein, we report for the first time the use of PFA in adult CHD patients with recurrent AT/AF. PFA turned out to be effective and generally safe. When using it in proximity to the coronary arteries, one must be aware of reversible coronary artery spasm. PFA might be a valuable tool to improve mid- and long-term outcome of AT/AF ablation in the adult CHD population.

Catheter ablation of atrial arrhythmias by using a multipolar grid-patterned high density mapping catheter in patients with congenital heart disease: a single-center experience

Abstract Objective Catheter ablation of arrhythmias in patients with congenital heart disease (CHD) remains challenging and time-consuming. A novel diagnostic catheter with a multipolar grid-patterned electrode configuration for high density mapping may reduce mapping time and enhance ablation success. Here we describe our experience of catheter ablation by using a multipolar grid-patterned mapping catheter in patients with CHD suffered from atrial tachycardia. Methods All patients with CHD underwent catheter ablation for atrial tachycardia by using multipolar grid-patterned high density mapping catheter between 04/2018 and 12/2021 were enrolled. Primary success was defined as non-inducibility of atrial tachycardia. Only the first catheter ablation was included in the study. Results A total of 37 consecutive patients (median age 34.2±33.0 years (range 7–65), female n=20) underwent 37 ablation procedures with initial high density mapping. The underlying heart defects were s/p ASD-closure (n=2), ASD-closure and corrected partial anomalous pulmonary venous return (n=2), corrected unroofed coronary sinus (n=1), pulmonary valve commissurotomy (n=2), repaired Tetralogy of Fallot (n=2), tricuspid and pulmonary valve replacement in PA/IVS (n=1), mitral valve replacement (n=1), Hypoplastic right heart syndrome (n=1), atrial switch procedure for dTGA (n=7), TA with Glenn shunt (n=1), Ross operation (n=1), Fontan palliation (tricuspid atresia n=6, DILV n=5, HLHS n=1, DORV n=1, dTGA n=1, criss-cross heart n=1, single ventricle n=1). A history of previous ablation was positive in 8 patients. During mapping of the cardiac chambers, the mean value of total collected points and used points were 32657.8±46171 and 3851.6±3295.5 respectively. Mean mapping and fluoroscopy time were 62.1±40.7 minute (range 3–178) and 11.4±8.5 minutes (range 0–32.2), respectively. There were 69 atrial tachycardia substrates in the 37 patients (median 2, range 1–4 per patient). All tachycardia substrates were completely ablated in 33/37 (89.2%) patients and partially in 4/37 (11.8%) patients. Acute success was achieved with successful ablation of 65 of 69 (94.2%) atrial substrates. During a median follow-up time of 20 months (range 5–49), recurrence rate was 5/65 (7.7%) atrial substrates in 5/37 (13.5%) patients. Comparison of 16 patients with Fontan palliation to the 23 patients without Fontan operation showed higher partially success rate in the patients with Fontan palliation (4/16 vs. 0/21, p=0.028). Conclusion In this series, high density mapping allowed elucidation of the tachycardia mechanism in all patients with a high primary ablation success, a limited radiation exposure and a low rate of arrhythmia recurrence. Funding Acknowledgement Type of funding sources: None.

Catheter ablation of atrial tachycardia originated from the left atrial epicardium.

A patient was referred with frequent atrial tachycardia (AT) attacks. Activation mapping showed that the left atrium (LA) roof was earlier activated with a broad region, and right atrial activation was delayed. The far-field A wave corresponding to the pulmonary artery area was advanced with failed ablation. Therefore, the AT could be left atrial epicardial origin, which was further confirmed by the successful ablation at earliest activated site at the epicardium.

Early recurrences after catheter ablation for atrial tachycardia: do we need a blanking period?

Abstract Funding Acknowledgements Type of funding sources: None. Background A blanking period after catheter ablation for atrial fibrillation is widely accepted. The clinical implications of early recurrences (ER) after ablation for atrial tachycardia (AT) in patients with a history of atrial fibrillation have not been analysed so far. Purpose To characterise ER and their relationship with late recurrences (LR) after AT ablation. Methods Acute and long-term outcome was studied in a total of 250 patients undergoing catheter ablation for consecutive AT. ER were defined as any documented atrial arrhythmia &amp;gt;30 s within 3 months after ablation. Results In our study population (66.5±0.7 years, 57.6% male), ER were detected in 80 patients (32.0%), with 74.0% of episodes occurring during the first month post-ablation. Patients with ER had a longer history of any atrial arrhythmia (9.1±0.9 years vs. 6.5±0.4 years; P=0.0283), a larger left atrial diameter (65.7±3.1 mm vs. 49.4±1.4 mm; P=0.0163) and a lower left ventricular ejection fraction (50.8±1.1% vs. 56.6±0.6%; P&amp;lt;0.0001) than those without ER. In patients with ER, AT were more often found to be mitral isthmus-dependent (16.5% vs. 6.2%; P=0.0048) or located at the crista terminalis (3.7% vs. 0.4%; P=0.0343). ER were associated with a 6.0-fold (95% CI 3.27-10.81; P&amp;lt;0.0001) and a 4.3-fold (95% CI 1.72-10.72; P=0.0023) increase in the risk of developing LR after a single or multiple ablation procedures, respectively (Figure). After a mean follow-up of 570±23 days, LR were detected in 78.0% vs. 76.9% vs. 50.0% of patients experiencing the first ER during the first, second or third month (P=0.2266). Among these groups, the first LR occurred after 188.7±20.2 days vs. 259.6±59.1 days vs. 400.8±55.5 days (P=0.0459). Conclusions ER after AT ablation are a predictor of LR and clinical as well as procedural risk factors are associated with the occurrence of ER. The prevalence of LR does not differ among patients with early vs. late ER. These findings underline the prognostic importance of ER and challenge the concept of a blanking period after catheter ablation for AT in patients with a history of atrial fibrillation.

Ablation index predicts outcomes of catheter ablation of focal atrial tachycardia: results of a multicenter study

Abstract Funding Acknowledgements Type of funding sources: None. Background Ablation index (AI) is a radiofrequency energy lesion quality marker integrating power, contact force, and time, which was recently shown to be linked to successful catheter ablation (CA) of atrial fibrillation, atrial flutter, and premature ventricular complexes. The possible role of AI as a predictor of outcomes after CA of focal atrial tachycardia (AT) has not been explored so far. Purpose To evaluate the role of AI as a predictor of arrhythmia-free survival after CA of focal AT. Methods We retrospectively enrolled forty-five consecutive patients undergoing CA for focal AT in four referral Italian electrophysiology laboratories. Clinical and procedural information were collected. For each patient, maximum and mean (by averaging maximum AI values for each radiofrequency ablation lesion) values of AI were measured. Focal AT-free survival was the primary outcome, and was assessed with repeated Holter monitors or cardiac implantable electronic devices, when available. The Shapiro-Wilk’s test was used to check continuous variables for normality; non-normal variables were expressed as median (1st-3rd quartile), whereas categorical variables were reported as counts and percentages. The primary outcome was assessed in a time-to-event fashion, with the Kaplan-Meier method, and the role of AI as a predictor of focal AT recurrence was tested with univariable Cox proportional hazard regression. Furthermore, differences in AI values between patients experiencing a primary outcome event and patients not experiencing a primary outcome event were analyzed with the Student t test. Discrimination ability of AI was measured with area under the receiver operating characteristic curve, and the optimal AI cutoff value was identified with Youden’s index. An alpha level &amp;lt;0.05 was considered statistically significant, and the software RStudio (RStudio Inc., Boston, MA) was used for statistical analysis. Results CA was acutely effective in every patient; however, 20% (n=9) of the study population had a focal AT recurrence over a median follow-up of 288 (160-560) days. Both maximum and mean AI values were significantly higher among patients without AT recurrences (maximum AI=568±91, mean AI=426±105) than in patients with AT relapses (maximum AI=447±142, mean AI=352±76, p=0.036 and p=0.028, respectively). All other procedural parameters were similar between the two groups. In a time-to-event analysis, only maximum AI was significantly associated with survival free from AT recurrence (p=0.001, Figure), whereas mean AI was not (p=0.08). By receiver operating characteristic (ROC) curve analysis, the optimal maximum AI cutoff for predicting effective CA according to Youden’s index was 461 (sensitivity, 0.89; specificity, 0.56). Conclusion We observed a strong association between maximum AI and outcomes, suggesting that maximum AI may be regarded as a quantitative marker of successful CA of focal AT.

P1 ATRIAL TACHYCARDIA IN PATIENT WITH TRANSFUSION–DEPENDENT BETA THALASSEMIA AND SEVERE HEMOCHROMATOSIS: A CASE REPORT

Abstract Background Beta thalassemia is the most common inherited disease and it’s characterized by the reduced synthesis of the beta–globin chains of the hemoglobin. Patients usually need long life transfusions since the disease leads to chronic hemolytic anemia. Iron chelation therapy is essential to prevent the chronic iron overload, which is responsible for heart failure, supraventricular and ventricular arrhythmias up to sudden cardiac death. Case Report A 31 year old female patient suffering from transfusion–dependent beta thalassemia has rarely taken iron chelation therapy during the years. Because of that, she developed a severe iron overload and heart failure. Furthermore, she started suffering from several episodes of supraventricular tachycardia and she was referred to our cardiological institution for medical help. She was initially treated with a pharmacological rhythm control strategy, which was ineffective. Then, even if the cardiac iron overload wasn’t completely resolved, we decided to perform an electrophysiological study and catheter ablation of atrial tachycardia. After the ablation, the patient had no more relapses during the follow up and she started to be more adherent with the iron chelation therapy. Discussion Cardiovascular complications are among the main causes of morbidity and mortality in patients suffering from beta thalassemia. Despite the wide use of iron–chelation therapy, today it’s still possible to find patients with severe iron overload. Furthermore, thalassemic patients have a high arrhythmic burden, especially for supraventricular arrhythmias. The best rhythm control treatment is represented by iron chelation therapy but there are still many doubts and open questions about the optimal pharmacological and interventional strategy. This clinical case shows how the interventional approach with catheter ablation can be an useful tool for rhythm control during the acute phase, even when the cardiac iron overload is still present.

Repeat radiofrequency catheter ablation of atrial tachycardias in patients with congenital heart disease.

Atrial tachycardias (AT) in patients with congenital heart disease (CHD) are significantly contributing to morbidity and mortality. Aim of this study was to evaluate the long-term course of CHD patients requiring repeat ablation procedures (RAP) of AT. All 144 patients with CHD who had undergone ablation of AT at our center between January 2003 and October 2018 were enrolled. Patients were classified according to the complexity of CHD: complex CHD (cCHD), moderate CHD (mCHD), and simple CHD (sCHD). A total of 101 RAP were performed in 64 patients. One RAP was performed in n = 40, two in n = 13, three in n = 10, and five in n = 1. Acute success rate was 82% (83/101) and was not associated with the complexity of CHD (p = 1.0). Number of procedures was lower in patients with sCHD than in patients with mCHD and cCHD (sCHD 1.3 ± 0.6, mCHD 1.8 ± 1.0, and cCHD 1.8 ± 1.1, p = .04). RAP were most frequent in patients after Fontan palliation or Atrial switch procedure (2.0 ± 1.1 [n = 41] vs. 1.6 ± 0.9 all others, p = .016) and in patients with multiple unstable AT's (2.5 ± 1.1 [n = 11] vs. 1.7 ± 1.0, p = .008). Major complications occurred in 4/101 procedures. Complete follow-up was available in 125 patients. Since last RAP 73% of the patients were in sinus/atrial rhythm and 34/125 patients (27%) with AT recurrence did not require re-ablation with mean follow-up of 52 ± 40 months. Recurrences after ablation of AT in CHD patients were frequent. After RAP promising long-term results could be achieved. Data encourage repetitive ablation procedures in this patient population.

Ablation Index Predicts Successful Ablation of Focal Atrial Tachycardia: Results of a Multicenter Study.

A radiofrequency energy lesion transmurality marker incorporating power, contact force, and time (Ablation Index, AI) was shown to be associated with outcomes of catheter ablation (CA) of multiple arrhythmias, but was never systematically assessed in the CA of focal atrial tachycardias (AT). We aimed to evaluate the role of AI as a predictor of outcomes in focal AT CA, and therefore, retrospectively included 45 consecutive patients undergoing CA for focal AT in four referral electrophysiology laboratories. Clinical and procedural information were collected. For each patient, maximum and mean (by averaging maximum AI values for each radiofrequency ablation lesion) AI were measured. The primary outcome was focal AT-free survival, and was systematically assessed with periodical Holter monitors or cardiac implantable electronic devices. CA was acutely effective in each case; however, 20% (n = 9) of the study population experienced a focal AT recurrence over a median follow-up of 288 days. Both maximum and mean AI values were significantly higher among patients without AT recurrences (maximum AI = 568 ± 91, mean AI = 426 ± 105) than in patients with AT relapses (maximum AI = 447 ± 142, mean AI = 352 ± 76, p = 0.036, and p = 0.028, respectively). The optimal cutoffs associated with freedom from recurrences were 461 for maximum AI (sensitivity, 0.89; specificity, 0.56) and 301 for mean AI (sensitivity, 0.97; specificity, 0.44). In a time-to-event analysis, maximum AI was significantly associated with survival free from AT recurrence (p = 0.001), whereas mean AI was not (p = 0.08). In summary, maximum AI is the best procedural parameter associated with the outcomes of CA for focal AT, and may help standardize the procedural approach.