Electroanatomical Voltage Mapping Research Articles

The importance of scar border zone size in VT presentation and recurrence in post MI patients

Abstract Introduction Available mapping data in post-myocardial infarction patients describe ventricular tachycardia (VT) re-entry circuit characteristics of slow VT, that are typically related to transmural scars. Fast VTs with cycle lengths close to the refractory period may be related to functional re-entry in the scar border zone. Functional re-entry related border zone VTs may be difficult to control by ablation. Purpose The aims of this study are (1) to describe electroanatomical voltage map (EAVM) characteristics in post myocardial infarction (MI) patients with spontaneous and inducible fast VTs and (2) to assess the relation between scar border zone size and ablation outcomes. Methods Consecutive post-MI patients undergoing VT ablation at a tertiary referral center from January 2012 to November 2018 were included. Fast VT was defined as a VT cycle length (VTCL) = ventricular refractory period + max. 30ms. Areas of scar border zone (using 0.5 – 2.1mV/3.0mV cut-offs (according to LV remodeling stage; LVEF<47% and LV end-systolic volume index of >50 ml/m2)) were measured on the EAVM and correlated with clinical outcomes. Results In total, 138 patients were included (86% male; left ventricular ejection fraction 35±10%; 86% remodeled LV). Twenty-three patients (17%) had ≥1 fast VT (mean VTCL 275±52ms) at presentation, mean VTCL of the remaining patients 397±88ms). The median scar border zone size was 27% [IQR 20-38] of the left ventricular endocardial surface. Patients who presented with a spontaneous fast VT had a larger border zone than patients with slower VT (32% [IQR 28 – 41] vs. 25% [IQR 16 – 36], p=0.01). After ablation, 79 (57%) patients remained inducible for any VT, including 59/79 (75%) for a fast VT (median VTCL fast VT 260ms [IQR 236 -280]). Patients who remained inducible for fast VTs had a larger border zone than patients who remained inducible for slower VTs (35% [IQR 27 – 44] vs. 26% [IQR 20 – 36], p<0.001). During a median follow-up of 26 months [IQR 8 – 47], 45 patients (33%) had a VT recurrence (mean VTCL 357±98ms). Patients with a below median (27%) scar border zone area had a lower VT recurrence rate compared to patients with an above median scar border zone area (recurrence rate: 16/66 (24%) vs. 29/72 (40%), p=0.03). Kaplan-Meier survival analysis showed better free VT survival in the below median border zone patients (Log-rank: p<0.05) (Figure 1). Conclusion Patients who present with spontaneous fast VTs or who remain inducible for fast VTs after ablation have larger scar border zones during EAVM compared to patients with presenting or remaining slower VTs. A larger border zone appeared to be associated with higher VT-recurrence rates. The scar border zone may play an important role as VT substrate for (fast) VTs and may not be easily targeted by current ablation techniques.VT-free survival stratified by median BZ

Volume-weighted unipolar voltage identifies diffuse fibrosis in patients with non-ischemic cardiomyopathy

Abstract Background Late-gadolinium enhanced cardiac magnetic resonance imaging (LGE-CMR) is currently used to identify non-ischemic scar. However, the distribution of non-ischemic fibrosis related to ventricular arrhythmia (VA) may vary between patients and cannot be accurately delineated by LGE-CMR. Myocardial extracellular volume fraction (ECV) is a promising tool to estimate the amount of diffuse fibrosis in non-ischemic cardiomyopathies (NICM). Novel intra-cardiac mapping derived tools, such as volume-weighted unipolar voltage (vwUV), may allow intraprocedural quantification of diffuse fibrosis. Purpose To evaluate the performance of vwUV to determine the segmental amount of non-ischemic fibrosis defined by whole-heart T1 mapping. Methods Consecutive patients with a left dominant NICM referred for ablation of VA, who underwent 3D LGE-CMR, whole-heart pre- and post-contrast T1 mapping and high density electroanatomical voltage mapping (EAVM) were included. CMR images were segmented and merged with the 3D EAVM data. The 16-segment AHA model was applied and vwUV and ECVs were determined per segment. Results Twenty-one patients (age 54 years [49-60], 18 males [87%], LVEF 47% [37-57%], LGE 7.7% (2.8-18.2%) of LV myocardium) were included and 305 segments analysed. The median ECV per patient was 30.3% (28.8-35.2%). The median segmental vwUV was 1.8mV (1.2-2.3mV). The basal septal and basal inferolateral segments tended to have higher ECV. However there was important variation between patients (figure 1). Of note, the segmental vwUV correlated well with segmental ECV (r = -0.53, p < 0.001) (figure 2). Conclusions For the first time, a segmental comparison has been performed between ECV and vwUV. There are important segmental variations of ECV between patients with a NICM referred for VA ablation. The novel intra-cardiac mapping-derived tool of vwUV can localize non-ischemic fibrosis and may facilitate substrate based ablation approaches in this challenging patient population.Figure 1.Segmental ECV valuesFigure 2.Segmental ECV and vwUV

Rhythm matters: sinus and pace rhythm map significantly differ in endo/epicardial 3D electroanatomic mapping

Abstract Introduction Left ventricular substrate assessment utilizing ultra-high density multipolar catheters is frequently used to guide ablation procedures in patients with scar related ventricular tachycardia. However, 3D electroanatomic mapping is often performed during either sinus or paced rhythm. The effect of the modality (sinus vs. paced) used during mapping on substrate assessment remains elusive. Methods and Results We compared biventricular endo- and epicardial 3D high-density voltage and activation maps in sinus- and right ventricular-paced rhythm in domestic pigs. Data was acquired using a 20-polar mapping catheter with a cardiac tissue proximity filter based on catheter location and impedance measurements. Ventricular pacing (120 bmp) was performed with a permanent pacemaker electrode in right ventricular septal position, and high-density maps were acquired from the endo- and epicardium in sinus and paced rhythm (criterion for low voltage: <0.5 mV). Electroanatomical voltage and activation high-density (>6500 points per heart) mapping were performed with sufficient coverage in the right and left ventricles and the epicardium. The size of the low voltage area varied significantly between sinus and right ventricular-paced rhythm, particularly in epicardial mapping. In SR, the total low voltage was 7.2 ± 5.8%, while 11.1 ± 0.03% in paced rhythm. SR and paced maps revealed e.g. low voltage areas in the basal to apical anterior wall corresponding to the LAD regions, however, this was especially pronounced in sinus maps (e.g. pig 1: 64.2 cm²) compared to the paced rhythm map (e.g. pig 1: 32.8 cm²). Conclusion The extent of low voltage regions differed significantly in RV/LV, endo- and epicardially. Sinus maps showed the most accurate electrical representation of local voltage and corresponded correctly to local anatomical landmarks like e.g. the LAD with its surrounding epicardial fat tissue.3D biventricular epicardial voltage map

Substrate characterization and outcomes of ventricular tachycardia ablation in amyloid cardiomyopathy: a worldwide study

Abstract Background the electrophysiological substrate underpinning ventricular tachycardia (VT) in cardiac amyloidosis (CA) remains elusive, and outcomes of catheter ablation in this peculiar population are currently unknown. Purpose we sought to describe the electrophysiological substrate and clinical outcomes of VT ablation in a cohort of patients with CA. Methods we included 19 consecutive patients (mean age, 69±10 years; male sex, 89%) with CA (ATTR, n=13; AL, n=6) undergoing catheter ablation for VT/ventricular fibrillation (VF) between 2013 and 2023 in a retrospective, observational, international study, involving 7 referral European and North American electrophysiology units. The primary efficacy outcome was recurrent VT/VF during follow-up, while the primary safety outcome included major procedure-related adverse events. Results the indication for ablation was drug-refractory VT in 16 patients (84%), and PVC-initiated polymorphic VT/VF in 3 (16%). Catheter ablation was performed using endocardial (n=14, 74%) or endo-epicardial approaches (n=5, 26%). Complete endocardial electroanatomical voltage maps of the left and right ventricles were obtained in 14 (74%) and 6 (32%) patients, respectively. Each patient had evidence of low-voltage areas, most commonly involving the interventricular septum (n=12); late potentials were recorded in 13 patients (68%). A median of 1 (1-2) VTs were inducible per patient; in 10 subjects (43% of mappable VTs), activation mapping was consistent with septal VT origin. Complete procedural success was obtained in 13 patients (68%), at the expense of 4 (21%) major procedure-related adverse events. After a median follow-up of 36 (18-54) months, sustained VT/VF recurrence was observed in 9 patients (47%); survival free from VT/VF recurrence was 74% (95%CI, 56-96%) at 12 months, and 53% (95%CI, 34-94%) at 36-month follow-up; the majority of patients remained on antiarrhythmic drugs (Figure). Low-voltage QRS (HR,21.96; p=0.022) and complete procedural success (HR,0.08; p=0.029) were associated with recurrent VT/VF at multivariable analysis (Figure). Conclusions catheter ablation of VT/VF is associated with favorable acute and mid-term arrhythmia control, yet with substantial risk of procedure-related complications and long-term recurrences. Septal substrate and frailty challenge successful management of patients with CA and VT/VF.Multimodality evaluation of LV substrateMain Study Outcomes

Arrhythmic mitral valve prolapse with versus without prior mitral valve repair: clinical profiles, electrophysiological substrates, and long-term clinical outcomes

Abstract Background Arrhythmic mitral valve prolapse (AMVP) is characterized by an arrhythmogenic left ventricular substrate, with high prevalence of myocardial scar. Whether patients with prior mitral valve repair for mitral valve prolapse (MVP) and new-onset complex ventricular arrhythmias (VAs) after cardiac surgery have different electroanatomical substrate and arrhythmic outcomes compared with AMVP patients without prior mitral valve surgery is currently unknown. Purpose We sought to compare the electroanatomical substrate and long-term clinical outcomes of patients with new-onset complex VAs after mitral valve surgery to AMVP patients without prior surgery. Methods We conducted a multicenter, prospective, observational study, enrolling MVP patients with prior mitral valve repair and new-onset complex VAs (>1000 premature ventricular contractions [PVCs]/day, nonsustained ventricular tachycardia [NSVT], and sustained VT) after cardiac surgery (group A,n=9), and patients with MVP, complex VAs and no prior surgery (group B,n=20). Each patient underwent a comprehensive diagnostic workup, including left ventricular electroanatomical mapping. Clinical-imaging data, as well as the location and segmental extension of both low-voltage areas and late potentials were assessed and compared between the two groups. The primary outcome was the occurrence of sustained VT or ventricular fibrillation(VF) during follow-up. Results In group A, complex VAs were first diagnosed after a median of 30(8-56) months following mitral valve repair. The characteristics of patients from the two study groups are presented in the Table. Patients from group A were older, sustained VT was nonsignificantly more common at baseline, the PVC count nonsignificantly higher, and LVEF nonsignificantly lower. Mitral annular disjunction was never observed in group A, while it was found in 7 patients from group B (p=0.066). At LV electroanatomical voltage mapping, bipolar and unipolar low-voltage areas (LVAs) were equally common in the two groups overall, and typically involved basal perimitral regions. However, patients from group B had concomitant bipolar and unipolar LVAs 50% of times, with larger unipolar LVAs, while patients from group A mostly showed isolated bipolar LVAs. Over a median follow-up of 15 (12-41) months, patients from group A (n=3, 33%) had slightly higher incidence of sustained VT or VF (HR: 1.91; 95% CI, 1.06-42.65; log-rank p=0.02, Figure) than patients from group B (n=2, 10%). Conclusion Compared to patients with AMVP and no prior cardiac surgery, patients with new-onset complex VAs after mitral valve repair for MVP have a slightly different clinical profile and electroanatomical substrate, characterized by predominant bipolar LVAs in the perimitral region. The long-term risk of major ventricular arrhythmias appears slightly higher in MVP patients with prior mitral valve surgery, mandating at least an equally careful risk assessment in both groups.

Adding Electroanatomical Mapping to Cryoballoon Pulmonary Vein Isolation Improves 1-Year Clinical Outcome and Durability of Pulmonary Vein Isolation: A Propensity Score-Matched Analysis.

Background: Adding electroanatomical left atrial (LA) voltage mapping to cryoballoon ablation (CBA) improves validation of acute pulmonary vein isolation (PVI). Aims: To determine whether the addition of mapping can improve outcome and PVI durability. Methods: One-year outcome and PV reconnection (PVR) rate at first repeat ablation were studied in 400 AF patients in a propensity-matched analysis (age, AF type, CHA2DS2-VASc score) between Achieve catheter-guided CBA with additional EnSite LA voltage maps performed pre- and post-CBA (mapping group; N = 200) and CT- and Achieve catheter-guided CBA (control group; N = 200). Clinical success was defined as freedom of documented AF or atrial tachycardia (AT) > 30 s. PV reconnection patterns were characterized in repeat ablations. Results: At 1 year, 77 (19.25%) patients had recurrence of AF/AT, significantly lower than in the mapping group: 21 (10.5%) vs. 56 (28%), p < 0.001. Procedure time was shorter (72.2 ± 25.4 vs. 78.2 ± 29.3 min, p = 0.034) and radiation exposure lower (4465.0 ± 3454.6 Gy.cm2 vs. 5940.5 ± 4290.5 Gy.cm2, p = 0.037). Use of mapping was protective towards AF/AT recurrence (HR = 0.348; 95% CI 0.210-0.579; p < 0.001), independent of persistent AF type (HR = 1.723; 95% CI 1.034-2.872; p = 0.037), and LA diameter (HR = 1.055; 95% CI 1.015-1.096; p = 0.006). At repeat ablation (N = 90), persistent complete PVI was seen in 14/20 (70.0%) versus 23/70 (32.9%) in the mapping and conventional group, respectively (p = 0.03). Reconnection rate of the right inferior PV was lower with mapping (10.0% vs. 34,3%, p = 0.035). Conclusions: Adding electroanatomical LA voltage mapping to CBA improves 1-year clinical outcome and lowers both procedure time and radiation exposure. At repeat, use of mapping increases complete persistent PVI mainly by improving PVI durability of the RIPV.

High FABP4, associated with low-voltage areas, increases the epicardial fibrosis and its glucose metabolism

Abstract Background High plasma levels of FABP4 were associated with epicardial fat volume on persistent AF patients. FABP4 can be released by differentiated adipocytes and macrophages, which can be involved in fibrosis. Purpose Our main objective was to study the association between FABP4 and epicardial fibrosis, which can explain low-voltage areas (LVA) and atrial fibrillation (AF) recurrence. Material and methods Peripheral levels of FABP4 and Galectin-3 were analysed on AF patients undergoing pulmonary vein isolation (PVI) (n=299) and signed informed consent. During the intervention, LVA was evaluated by invasive electroanatomic voltage mapping (EAM). Epicardial (EAT) (n=6) and subcutaneous adipose tissue (SAT) (n=5) were obtained from undergoing open heart surgery patients. Stromal cells were isolated by collagenase digestion, cultured and treated with and without FABP4 100 ng/mL and/or galectin-3 30 ng/mL for 24 hours. The proliferation and migration rate were measured by wound healing assay; mitochondrial activity was studied by MTT assay; and glucose and lactate consumption were detected by colorimetric and fluorescence enzymatic assays, respectively. Gene expression levels were assessed by real-time PCR. Results Regression analysis determined that the main independent predictors of LVA were age, left atrial area and FABP4 levels. Preclinical "in vitro" studies have shown that FABP4 100 ng/mL induced fibrosis in epicardial stromal cells (p=0.0039) and subcutaneous stromal cells (p=0.0009), evidenced by wound healing assay and by the increment of associated fibroblast genes (COL1A2, VIM, TGF-β1). Moreover, the high FABP4 concentration modulates the protein levels and metabolic genes expression (CPT1, FASN, ATGL, related to transport, synthesis and degradation of fatty acids, respectively) on EAT stromal cells. Glucose metabolism without lactate production was also incremented after FABP4 treatment (p&amp;lt;0.0001). Even, on SAT cells, released lactate was reduced after FABP4 treatment (p=0.0218). Conclusions Plasma FABP4 was a predictor of LVA. Our results suggest that this association might be explained by the fibrotic and metabolic role of FABP4 in epicardial cells. Future studies will shed light on the benefits on atrial remodelling with FABP4 modulators.Figure 1Figure 2

The electrophysiological substrate of biopsy-proven cardiac amyloidosis

Abstract Background Cardiac amyloidoses (CA) are an increasingly recognized group of infiltrative cardiomyopathies associated with high risk of major adverse cardiac events. Endomyocardial biopsy (EMB) may be required to differentiate the amyloid type (mainly, Immunoglobulin light chain [AL] versus transthyretin-related [ATTR]) in some cases. Purpose The aim of this study was to provide the first description of the right ventricular (RV) electroanatomical substrate of CA, and assess its association with EMB findings and clinical outcomes. Methods We enrolled ten consecutive patients undergoing EMB for suspected CA (median age, 68[63-77]; male, 50%) in a monocentric, observational, retrospective study. All patients had a clinical diagnosis of CA, but a diagnosis of CA type was hampered by the presence of inconclusive or discordant laboratory-imaging findings (abnormal serum free light chain assay and positive bone scintigraphy, n=5; ambiguous imaging results, n=4; abnormal serum free light chain assay and TTR gene mutation, n=1). Therefore, each patient underwent RV high-density electroanatomical voltage mapping (EVM) and EMB. The primary outcome was death or hospitalization at 1-year follow-up. We recorded electrogram features at EMB sampling sites and in the overall RV, and explored their correlations with histopathological findings and primary outcomes events. Results A final EMB-proven diagnosis of AL or ATTR CA was formulated in 6 and 4 patients, respectively. Electrogram amplitudes in the bipolar and unipolar configurations averaged 1.58±0.65 mV, and 5.38±1.41 in the overall RV. We found a significant inverse correlation between unipolar electrogram amplitude and amyloid burden at EMB (p&amp;lt;0.001); the unipolar voltage cutoff that best identified regions with &amp;gt;15% amyloid tissue infiltration according to Youden index was 9.1 mV (sensitivity, 43%; specificity, 100%; accuracy, 77%). At 1-year follow-up, 6 patients (60%) experienced a primary outcome event. Compared to subjects with uneventful follow-up, patients with a primary outcome event had larger unipolar low-voltage zones (32.3 [6.1] cm2 vs. 20.7 [6.5] cm2, p=0.043) and bipolar dense scar areas (6.1 [2.3] cm2 vs. 1.8 [0.7] cm2, p=0.005), and after pooling mapping points from all patients, unipolar electrogram amplitude was moderately associated with primary outcome events (AUC: 0.65 [95% CI, 0.64-0.65]). Conclusions In CA, electrogram amplitudes are around the lower limit of normal, yet disproportionately low compared to the increased wall thickness. We found evidence that unipolar electrogram amplitude may be a quantitative marker of amyloid burden, possibly associated with adverse clinical outcomes.EVM and EMB in ATTR cardiac amyloidosisEVM and EMB in AL cardiac amyloidosis

Biatrial flutters: unique circuits requiring a customized ablation approach

Abstract Introduction Atrial futters are macroreentrant tachycardias that typically involve several walls of a certain atrium, being the other atrium passively activated. Biatrial flutters (BAF) are peculiar macro-reentries associated with anterior/septal scars, involving both atria and using the interatrial connections. Purpose To characterize the mechanism of BAF a cohort of patients (pts) submitted to mapping and ablation. Methods Retrospective single-center study of pts with atypical atrial flutter submitted to ablation from 2015 to 2022. High resolution electroanatomical voltage and activation mapping were collected using Carto, Ensite or Rhythmia. Whenever the arrhythmia circuit was not fully displayed in a certain atrium, of the other atrium was mapped to fully characterize the reentrant circuit and establish the critical isthmus. Biatrial circuits were classified into 4 types: type 1, involving the mitral annulus and the tricuspid annulus, escaping the septal wall in both atria; type 2 using most of the mitral annulus and the right atrium (RA) septum; type 3, using both the left atrium (LA) and RA septum; and type 4, using most of the tricuspid annulus and the LA septum. Acute and long-term success was evaluated. Results From a total of 107 pts submitted to atypical flutter ablation, 5 pts presented BAF (3 male, median age: 55-yo), 4 of them previously submitted to cardiac surgery (CABG in 1, mitral valvuloplasty in 1, mitral+tricuspid valvuloplasty in 1 and surgical correction of aortic coarctation and ostium primum atrium septal defect in 1) and 1 had been previously submitted to pulmonary vein isolation (PVI), empirical roof line and cavotricuspid isthmus (CTI) ablation. A proximal-to-distal coronary sinus activation and extensive low-voltage areas at the septum were recognized in all these pts. The BAF mechanism was single loop in all of them, with a type 2 circuit in 2 pts, and types 1, 3 and 4 in one patient each. BAF types 1 and 4 were terminated with CTI ablation. BAF types 2 and 3 were terminated with linear ablations from the mitral annulus to the right superior PV, complemented with focal applications at Bachmann bundle insertion sites in the pts with type 2 BAF. Acute success was achieved in all pts. During a mean time of follow-up of 344±91 days, 1 pt had AFl recurrence. Conclusion BAF is a rare and complex arrhythmia, which is possible to ablate successfully by applying high-density mapping tools, a comprehensive analysis of the substrate/activation maps and a mechanism-tailored ablation strategy.

Characteristics and Clinical Value of Electroanatomic Voltage Mapping in Cardiac Amyloidosis

BackgroundCardiac amyloidoses (CAs) are an increasingly recognised group of infiltrative cardiomyopathies associated with high risk of adverse cardiac events. We sought to characterise the characteristics and clinical value of right ventricular (RV) electroanatomic voltage mapping (EVM) in CA. MethodsFifteen consecutive patients undergoing endomyocardial biopsy (EMB) for suspected CA (median age 75 years, 1st-3rd quartiles 64-78 years], 67% male) were enrolled in an observational prospective study. Each patient underwent RV high-density EVM using a multipolar catheter and EMB. The primary outcome was death or heart failure hospitalisation at 1-year follow-up. We recorded electrographic features at EMB sampling sites and electroanatomic data in the overall RV, and explored their correlations with histopathologic findings and primary outcomes events. ResultsA final EMB-proven diagnosis of immunoglobulin light chain or transthyretin CA was formulated in 6 and 9 patients, respectively. Electrogram amplitudes in the bipolar and unipolar configurations averaged 1.55 ± 0.44 mV and 5.14 ± 1.50 mV, respectively, in the overall RV, with lower values in AL CA patients. We found a significant inverse correlation between both bipolar and unipolar electrogram amplitude and amyloid burden according to EMB (P = 0.001 and P = 0.025, respectively). At 1-year follow-up, 7 patients (47%) experienced a primary outcome event; the extent of bipolar dense scar area at RV EVM was an independent predictor of primary outcome events at multivariable analysis (odds ratio 2.40; P = 0.037). ConclusionsIn CA, electrogram amplitudes are around the lower limit of normal yet disproportionately low compared with the increased wall thickness. Out data suggest that RV electrogram amplitude may be a quantitative marker of amyloid burden, and that RV EVM may have prognostic value.

Electroanatomical voltage mapping with contact force sensing for diagnosis of arrhythmogenic right ventricular cardiomyopathy

BackgroundThree-dimensional electroanatomical mapping (EAM) can be helpful to diagnose arrhythmogenic right ventricular cardiomyopathy (ARVC). Yet, previous studies utilizing EAM have not systematically used contact-force sensing catheters (CFSC) to characterize the substrate in ARVC, which is the current gold standard to assure adequate tissue contact. ObjectiveTo investigate reference values for endocardial right ventricular (RV) EAM as well as substrate characterization in patients with ARVC by using CFSC. MethodsEndocardial RV EAM during sinus rhythm was performed with CFSC in 12 patients with definite ARVC and 5 matched controls without structural heart disease. A subanalysis for the RV outflow tract (RVOT), septum, free-wall, subtricuspid region, and apex was performed. Endocardial bipolar and unipolar voltage amplitudes (BVA, UVA), signal characteristics and duration as well as the impact of catheter orientation on endocardial signals were also investigated. ResultsARVC patients showed lower BVA vs. controls (p = 0.018), particularly in the subtricuspid region (1.4, IQR:0.5–3.1 vs. 3.8, IQR:2.5-5 mV, p = 0.037) and RV apex (2.5, IQR:1.5–4 vs. 4.3,IQR:2.9–6.1 mV, p = 0.019). BVA in all RV regions yielded a high sensitivity and specificity for ARVC diagnosis (AUC 59–78%, p < 0.05 for all), with the highest performance for the subtricuspid region (AUC 78%, 95% CI:0.75–0.81, p < 0.001, negative predictive value 100%). A positive correlation between BVA and an orthogonal catheter orientation (46°-90°:r = 0.106, p < 0.001), and a negative correlation between BVA and EGM duration (r = −0.370, p < 0.001) was found. ConclusionsEAM using CFSC validates previous bipolar cut-off values for normal endocardial RV voltage amplitudes. RV voltages are generally lower in ARVC as compared to controls, with the subtricuspid area being commonly affected and having the highest discriminatory power to differentiate between ARVC and healthy controls. Therefore, EAM using CFSC constitutes a promising tool for diagnosis of ARVC.

Endomyocardial substrate of ventricular arrhythmias in patients with autoimmune rheumatic diseases.

Delayed enhancement-magnetic resonance imaging (DE-MRI) has demonstrated that nonischemic cardiomyopathy is mainly characterized by intramural or epicardial fibrosis whereas global endomyocardial fibrosis suggests cardiac involvement in autoimmune rheumatic diseases or amyloidosis. Conduction disorders and sudden cardiac death are important manifestations of autoimmune rheumatic diseases with cardiac involvement but the substrates of ventricular arrhythmias in autoimmune rheumatic diseases have not been fully elucidated. 20 patients with autoimmune rheumatic diseases presenting with ventricular tachycardia (VT) (n = 11) or frequent ventricular extrasystoles (n = 9) underwent DE-MRI and/or endocardial electroanatomical mapping of the left ventricle (LV). Ten patients with autoimmune rheumatic diseases underwent VT ablation. Global endomyocardial fibrosis without myocardial thickening and unrelated to coronary territories was detected by DE-MRI or electroanatomical voltage mapping in 9 of 20 patients with autoimmune rheumatic diseases. In the other patients with autoimmune rheumatic diseases, limited regions of predominantly epicardial (n = 4) and intramyocardial (n = 5) fibrosis or only minimal fibrosis (n = 2) were found using DE-MRI. Endocardial low-amplitude diastolic potentials and pre-systolic Purkinje or fascicular potentials, mostly within fibrotic areas, were identified as the targets of successful VT ablation in 7 of 10 patients with autoimmune rheumatic diseases. Global endomyocardial fibrosis can be a tool to diagnose severe cardiac involvement in autoimmune rheumatic diseases and may serve as the substrate of ventricular arrhythmias in a substantial part of patients.

"Abnormal Voltage in Electro-Anatomical Voltage Mapping of Left Atrial Appendage Absence: Case Report and Review of the Literature"

"Abnormal Voltage in Electro-Anatomical Voltage Mapping of Left Atrial Appendage Absence: Case Report and Review of the Literature"

Quantification of atrial cardiomyopathy disease severity by electroanatomic voltage mapping and cardiac magnetic resonance imaging

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): The authors acknowledge the support of the British Heart Foundation Centre for Research Excellence Award III (RE/18/5/34216). SEW is supported by the British Heart Foundation (FS/20/26/34952). Background Atrial late gadolinium enhancement (Atrial-LGE) and electroanatomic voltage mapping (Atrial-EAVM) quantify the anatomical and functional extent of atrial cardiomyopathy. Prior studies provide conflicting information relating to the level of agreement between these modalities for the assessment of atrial cardiomyopathy disease severity. Purpose We aimed to explore the relationships between, and outcomes from, these contrasting measures of atrial cardiomyopathy disease severity in patients with atrial fibrillation undergoing ablation. Methods Atrial-LGE and Atrial-EAVM was performed in patients undergoing first-time ablation for atrial fibrillation. Atrial cardiomyopathy disease severities were quantified using CEMRGApp and OpenEP[1] for Atrial-LGE and Atrial-EAVM, respectively. Correlations between modalities, their relationships with clinical features and their relationships with arrhythmia recurrence were assessed. Results Atrial-LGE and Atrial-EAVM quantification of atrial cardiomyopathy disease was performed In 123 atrial fibrillation patients (60±10 years, paroxysmal (n=58), persistent (n=65)) (Figure 1, panel A). Atrial-EAVM was moderately correlated with Atrial-LGE (r=0.41, P&amp;lt;0.001), with a mean fibrosis burden of 32.4±21.8% (Figure 1, panel B). The strength of the correlation was dependent on the thresholds chosen to define abnormal atrial tissue. The thresholds yielding the strongest correlation were IIR &amp;gt;0.97 (for Atrial-LGE) and voltage &amp;lt;1.17 mV (for Atrial-EAVM). Using these thresholds, agreement between modalities was strongest amongst patients in the highest tertile of fibrosis burden (mean of differences 5.9% (95% CI -30.4% to 42%)). Fibrosis burden was greater for Atrial-LGE than Atrial-EAVM (46.4±7.48% versus 13.7±7.13%, P&amp;lt;0.005) for patients in the lowest tertile of fibrosis burden (Figure 1, panel C). These patients were younger, had smaller atria and a greater frequency of paroxysmal atrial fibrillation than patients in the higher tertiles of fibrosis burden (Figure 2). Atrial cardiomyopathy disease severity was greater in patients with arrhythmia recurrence for both Atrial-EAVM (39.3±23.1% versus 28.5±20.2%, P=0.010) and Atrial-LGE (58.69±11.60 versus 53.33±9.63, P=0.011). In multivariable analysis, Atrial-LGE (OR 1.04 (95% CI 1.00-1.09), P=0.037) was independently associated with arrhythmia recurrence. Conclusions We demonstrate for the first time that the level of agreement between Atrial-EAVM and Atrial-LGE is dependent on the level of atrial cardiomyopathy disease severity. The functional consequences of atrial cardiomyopathy are most evident in patients with the highest anatomical extent of disease. This explains variations in prior studies and will inform future clinical applications of these techniques.

Electroanatomical voltage mapping with a force-sensing technology catheter for diagnosis of Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Invasive three-dimensional electroanatomical mapping (EAM) can be helpful to diagnose arrhythmogenic right ventricular cardiomyopathy (ARVC). Contact force sensing catheters (CFSC) represent the gold standard to verify adequate tissue contact during EAM. However, normal reference values for right ventricular (RV) EAM as well as substrate characterization in patients with ARVC using CFSC have not been systematically investigated, which was the aim of this prospective study. Methods EAM of the RV during sinus rhythm was performed with the Thermocool SmartTouch catheter via a long sheath in the CARTO3 system in 11 patients with definite ARVC and 5 age- and gender-matched control subjects without structural heart disease. Only points with a mean contact force of ≥4G were analyzed. To account for differences due to RV anatomy, it was divided into 5 segments: RV outflow tract (RVOT), septum, free wall, sub-tricuspid region and apex. Endocardial bipolar and unipolar voltages, signal characteristics and signal duration were analyzed. The impact of catheter orientation on endocardial signals was also assessed. Results A median of 227 (IQR:120-364) endocardial RV points were analyzed. Median bipolar voltage in healthy controls was 3.8mV (range 3.6-4.6, IQR 2.7-5.4), with lower values in the RVOT and higher values in the RV septum. ARVC patients showed significantly lower bipolar voltages as compared to controls (repeated measures ANOVA; between-subjects effect: F=6.443,p=0.024), showing significantly lower bipolar voltage values in the sub-tricuspid region (1.8±1.9vs.4.6±2.9mV,p=0.031) and in the RV apex (2.9±1.4vs.7.2±5.2mV,p=0.024), Figure 1c. Bipolar voltage values in all RV regions yielded a high sensitivity and specificity for ARVC diagnosis (AUC62-78%,p&amp;lt;0.001 for all), with the highest performance for the sub-tricuspid region (AUC78%,95%CI0.75-0.81,p&amp;lt;0.001). A bipolar voltage value &amp;lt;1.5mV in the sub-tricuspid region yielded a sensitivity of 98% and a specificity of 53% for ARVC diagnosis (Figure 1a-b, showing the typical RV free wall "C-scar" in ARVC and normal values for the RV apex in less advanced disease stages). A positive correlation between bipolar voltage values and an orthogonal catheter orientation (46°-90°: r=0.106,p&amp;lt;0.001) as well as a higher catheter contact force (r=0.054,p=0.008), and a negative correlation between bipolar voltage values and QRS duration (r=-0.370,p&amp;lt;0.001) was found. Conclusions For the first time a systematic analysis of RV endocardial low voltage areas in ARVC patients as compared to controls by using CFSC was performed, and confirmed that RV voltages are generally lower in ARVC as compared to controls, with the sub-tricuspid area showing the lowest values and highest discriminatory power vs controls.

Utility of ST2 soluble biomarker in patients with atrial fibrillation and pulmonary veins isolation

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): No fundings related Background Atrial fibrillation (AF) is the more frequent arrhythmia in clinical practice and the efficacy of pulmonary vein ablation has being widely demonstrated. There is still a lack of information about the predictive value of electroanatomical voltage maps or biomarkers to predict recurrence. Purpose ST2 soluble (ST2S) biomarker has being previously analyzed by our group in patients with AF and electrical cardioversion demonstrating utility to predict recurrence . So we sought to analyze the clinical utility of ST2S biomarker in patients with AF that underwent to an electrophysiology study and pulmonary isolation (PVI) to compare the predictive value of this biomarker. Results This was a prospective, observational clinical trial that included a total of 156 patients with AF who were referred to our hospital for a PVI from September 2016 to September 2019. We also included 40 matched control patients for the initial analysis. All the patients with AF underwent an electroanatomical voltage map in sinus rhythm and PVI. From the 156 PVI: 68 had paroxysmal AF and 88 persistent. ST2S mean value in AF patients was of (13178.5 pg/ml) and had no significant difference with matched controls (11016.2 pg/ml) in baseline analysis. There was no association of ST2S baseline values and recurrence in AF patients. When we analyzed by type of AF, persistent AF patients had a significantly higher level of the biomarker and there was also a significant elevation of the biomarker according to heart rate (&amp;gt;100 bpm) (p 0.038). We observed an elevation of the ST2S levels at 3 and 6 months follow-up with no difference according to recurrence. The levels of ST2S were lower in the cases with a lower voltage map area and in the cases with a wider lower map area but there was no a significant association nor with recurrence. In multivariant analysis only AF rhythm and LA index volume was a significant predictor or recurrence at 3 months follow-up. Conclusions We consider that even though there is an association with AF patients and ST2S biomarker levels, specially in those with persistent AF, in patients undergoing an PVI, ST2S values had a generalized elevation at follow-up probably related to inflammation and were not predictive of recurrence.

Pulsed-field ablation for redo procedures after failed radiofrequency or cryo ablation for atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulsed-field ablation (PFA) has recently been introduced for pulmonary vein isolation (PVI). It might also be of potential value for redo procedures after failed radiofrequency or cryo ablation for atrial fibrillation (AF). Purpose To describe our initial experience using a multipolar PFA catheter for redo procedures after failed AF ablation. Methods Consecutive patients undergoing a redo procedure for recurrent atrial arrhythmias at our institution using a multipolar PFA catheter from Mai 2021 until October 2022 were included. A 3D electro-anatomical bipolar voltage map was generated to identify pulmonary vein (PV) reconnection, quantify the level of isolation (antral vs. ostial isolation), and characterize the extent of extra-PV low-voltage tissue. In case of PV reconnection, re-isolation was performed using PFA, with at least four applications in both basket and flower configuration. In case of only ostial PV isolation, additional PFA applications in flower configuration were delivered to widen the isolation to a more antral level. If all veins were already isolated on an antral level and/or if low-voltage areas were found on the posterior wall, a posterior wall ablation was added with the same PFA device at the discretion of the operator. Results We identified 170 patients (mean age: 64 ±11years, 45 (27%) women), undergoing a redo procedure using PFA. The median number of previous ablations was 1 (range 1-6), the most recent ablation was performed using radiofrequency in 122 (72%), cryo in 42 (25%), and surgery in 5 (3%) patients. In 104 (61%) patients, at least one reconnected PV was found. In total, 244 of 680 PV (36%) showed reconnection. In addition to PV reisolation, additional antral applications were delivered in 205 of 436 still isolated veins (47%). Posterior wall ablation was added in 112 (66%) patients (43% in paroxysmal AF, 78% in persistent AF, Figure). Median procedure duration was 101 minutes (IQR 80-137). There was no cardiac tamponade, no stroke, and no esophageal fistula observed in this cohort. Conclusion For patients with recurrence after catheter ablation of atrial fibrillation, re-ablation using PFA is feasible and safe. Most common ablation targets were the pulmonary veins and the posterior wall. Whether the complementary effect of a different technology improves outcome needs further investigation.

PO-03-069 COHERENT SINE BURST ELECTROPORATION (CSE) FOR PULSED FIELD ABLATION: PRELIMINARY CLINICAL OUTCOMES FOR TREATMENT OF PAROXYSMAL AND PERSISTENT AF IN THE BURST-AF TRIAL

Pulsed field ablation (PFA) has a promising safety profile for treatment of atrial fibrillation. PFA is currently implemented using square waves and varying circular, multi-spline, focal, or basket catheter designs. Coherent Sine Burst Electroporation (CSE) is a novel PFA platform that uses phased sine waves delivered via a configurable catheter to produce linear, circular, or focal lesions. Investigate the acute safety and efficacy of CSE for pulmonary vein isolation (PVI), posterior wall isolation (PWI), and cavo-tricuspid isthmus (CTI) ablation in patients with paroxysmal (PAF) and persistent AF (PersAF). BURST-AF is a first-in-human, non-randomized, multicenter, single-arm trial of PAF and PersAF ablation (NCT05572047). CSE was delivered with sine waves of amplitude 2400–2900V (standard-energy) and 3000–3500V (high-energy) using a multi-configurable 7F ablation catheter (Arga MedTech Inc, San Diego, CA, USA). After informed consent and under general anesthesia, ICE-guided transseptal puncture was performed. An 8.5F deflectable sheath guided the ablation catheter into the left atrium (LA). Electro-anatomic anatomy and voltage maps were created. A minimum of 3 applications of ablation per vein including rotation were applied at each PV ostium to achieve PVI. In patients (pts) with PersAF, the linear configuration was used for PWI and CTI. PV entrance and exit block was assessed after 20-min waiting period. ICE was used to assess microbubble formation. Re-map will be performed 60-days post procedure to evaluate lesion durability. The first 5 pts were enrolled in Oct 2022. Acute safety was observed for all pts (age 62.6 ± 7.56 yrs, F/M = 80/20%, BMI 32 ± 5.7). No serious adverse events occurred. First-pass acute electrical isolation was achieved in 100% of PVs (n=20) and also in the PersAF pt for PWI and CTI. PVI duration (from 1st to last lesion) was 46.6 ± 28.5min (range 28 - 95). PVI LA dwell time was 58.6 ± 37.7min and fluoro time was 20.4 ± 6.8 min. Initial findings of CSE PFA demonstrated acute first-pass efficacy for PVI, PWI, and CTI. Additional pts and re-map data for durability assessment will be available at time of presentation. CSE allows application of high energy protocols (up to 3500V) with no microbubble formation and minimal to no muscle stimulation. The CSE Ablation Catheter facilitates focal, linear, and circular ablations, comprising a highly versatile tool for cardiac arrhythmias.

Clinical Impact of Cardiac Fibrosis on Arrhythmia Recurrence after Ablation in Adults with Congenital Heart Disease

Adults with congenital heart disease (ACHD) are often affected by cardiac arrhythmias requiring catheter ablation. Catheter ablation in this setting represents the treatment of choice but is flawed by frequent recurrencies. Predictors of arrhythmia relapse have been identified, but the role of cardiac fibrosis in this setting has not been investigated. The aim of this study was to determine the role of the extension of cardiac fibrosis, detected by electroanatomical mapping, in predicting arrhythmia recurrencies after ablation in ACHD. Consecutive patients with congenital heart disease and atrial or ventricular arrhythmias undergoing catheter ablation were enrolled. An electroanatomical bipolar voltage map was performed during sinus rhythm in each patient and bipolar scar was assessed according to the current literature data. During follow-up, arrhythmia recurrences were recorded. The relationship between the extent of myocardial fibrosis and arrhythmia recurrence was assessed. Twenty patients underwent successful catheter ablation of atrial (14) or ventricular (6) arrhythmias, with no inducible arrhythmia at the end of the procedure. During a median follow-up period of 207 weeks (IQR 80 weeks), eight patients (40%; five atrial and three ventricular arrhythmias) had arrhythmia recurrence. Of the five patients undergoing a second ablation, four showed a new reentrant circuit, while one patient had a conduction gap across a previous ablation line. The extension of the bipolar scar area (HR 1.049, CI 1.011-1.089, p = 0.011) and the presence of a bipolar scar area >20 cm2 (HR 6.101, CI 1.147-32.442, p = 0.034) were identified as predictors of arrhythmia relapse. The extension of the bipolar scar area and the presence of a bipolar scar area >20 cm2 can predict arrhythmia relapse in ACHD undergoing catheter ablation of atrial and ventricular arrhythmias. Recurrent arrhythmias are often caused by circuits other than those previously ablated.

Pulmonary Vein Myocardial Sleeve Length and its Association With Sex and 4q25/PITX2 Genotype

BackgroundExperimental evidence suggests genetic variation in 4q25/PITX2 modulates pulmonary vein (PV) myocardial sleeve length. Although PV sleeves are the main target of atrial fibrillation (AF) ablation, little is known about the association between different PV sleeve characteristics with ablation outcomes. ObjectivesThis study sought to evaluate the association between clinical and genetic (4q25) risk factors with PV sleeve length in humans, and to evaluate the association between PV sleeve length and recurrence after AF ablation. MethodsIn a prospective, observational study of patients undergoing de novo AF ablation, PV sleeve length was measured using electroanatomic voltage mapping before ablation. The sentinel 4q25 AF susceptibility single nucleotide polymorphism, rs2200733, was genotyped. The primary analysis tested the association between clinical and genetic (4q25) risk factors with PV sleeve length using a multivariable linear regression model. Covariates included age, sex, body mass index, height, and persistent AF. The association between PV sleeve length and atrial arrhythmia recurrence (>30 seconds) was tested using a multivariable Cox proportional hazards model. ResultsBetween 2014 and 2019, 197 participants were enrolled (median age 63 years [IQR: 55 to 70 years], 133 male [67.5%]). In multivariable modeling, men were found to have PV sleeves 2.94 mm longer than women (95% CI: 0.99-4.90 mm; P < 0.001). Sixty participants (30.5%) had one 4q25 risk allele and 6 (3.1%) had 2 alleles. There was no association between 4q25 genotype and PV sleeve length. Forty-six participants (23.4%) experienced arrhythmia recurrence within 3 to 12 months, but there was no association between recurrence and PV sleeve length. ConclusionsCommon genetic variation at 4q25 was not associated with PV sleeve length and PV sleeve length was not associated with ablation outcomes. Men did have longer PV sleeves than women, but more research is needed to define the potential clinical significance of this observation.