Analysis of Similarities and Differences between Biatrial Remodeling Through Electro-Anatomic Mapping in Patients with Atrial Fibrillation.

Left atrium regional voltage analysis in sinus rhythm in patients undergoing atrial fibrillation ablation

BI-ATRIAL MAPPING AND ELEVATED HEART RATES IDENTIFY ABNORMAL ATRIAL SUBSTRATE IN ATRIAL FIBRILLATION PATIENTS WITHOUT LOW-VOLTAGE AREAS IN THE LEFT ATRIUM

BackgroundSubstrate ablation strategies in addition to pulmonary vein isolation (PVI) for the maintenance of sinus rhythm (SR) are still debated. Targeting low voltage areas (LVA) in addition to PVI may represent an efficient strategy for the ablation of persistent atrial fibrillation (AF).PurposeSCAR-AF study (ablation of LVA during sinus rhythm) was a multicenter, prospective, randomized trial, evaluating the effect of LVA ablation in addition to PVI for persistent AF on SR maintenance.MethodsFrom September 2019 to August 2021, patients with de novo persistent AF were included in the study. After LA mapping guided by a 3D mapping system, patients were divided according to the presence or absence of LVA. Patients without LVA were treated by PVI only (Group A). Patients with LVA were randomized to PVI only (Group B) or PVI + ablation of LVA (Group C). LVA was defined as voltage mapping with bipolar atrial voltage <0.5 mV. The primary endpoint was freedom from atrial arrhythmias, after a single ablation procedure.ResultsA total of 211 patients (Sex male: 73%, Mean Age 63.8+/-9.3 years, CHADS-VASC 2.1, long standing AF 33.5%). After 18 months FU, atrial-arrhythmia-free survival did not differ significantly between the 3 groups, 79% in Group A, 75.7% in Group B, 73.1% in Group C (Group A vs Group B: HR: 1.28; 95% CI: 0.64-2.55, p = .48, Group B vs Group C: HR 95%CI: 0.67-2.45; p = 0.45). Multivariate analysis showed that presence of LVA was associated with age (years) (HR 1.11 CI 1.06 – 1.16, p < 0.001) and inversely correlated with BMI (kg/m²) (HR 0.93, CI 0.87 – 0.99, p 0.029) and current smoking.ConclusionIn this randomized trial, PVI plus ablation of LVA did not significantly improved outcomes in patients with persistent AF. LVA may represent a marker of severe atrial cardiomyopathy.

Introduction Pulmonary vein isolation (PVI) is recommended during all atrial fibrillation (AF) catheter ablation procedures. In nearly half of patients with persistent AF, low voltage areas (LVAs), commonly defined as areas in left atrium (LA) with a bipolar electrogram amplitude of &amp;lt; 0.5 mV, could be documented during electrophysiological study (EP). The remaining presence of these areas in LA after a PVI-only catheter ablation procedure is identified as a risk factor for recurrence of AF. Targeting and ablating (substrate modification) these areas reduces recurrency of AF. Pre-procedural identification of patients with additional LVAs is thus very important, until date very challenging and not established. Many markers are evaluated but it remains elusive. Extensive adipose tissue in obese patients leads to LA enlargement and remodeling via different mechanisms, leading to higher incidence of AF. The link between obesity and presence of LVAs in LA other than of pulmonary veins (PV) is to our knowledge not yet evaluated. Aim of the study Is to evaluate role of body mass index (BMI) in the presence of low voltage areas in left atrium besides pulmonary vein by comparing the BMI in patients with persistent AF with and without LVAs in LA, thus eventually identifying BMI as a possible pre-procedural marker of the presence of these areas. Methodology We analyzed data from 91 consecutive patients with persistent AF undergoing first time LA catheter ablation from 09/2021 until 10/2023 inside of the Jen-PACE study. In all patients a high-density 3D endocardial voltage mapping was carried out using EnSite Precision™/ Ensite X™ and the Advisor™ HD-Grid Mapping Catheter. Results The mean BMI was 29.6 ± 4.8, mean LV-EF was 53,4% ± 9.7, 24 patients (27%) were females, average age was 67 years. Depending on the presence of low voltage areas, the patients underwent either PVI only when no such areas were documented (61 patients, 67%) or PVI and substrate modification (30 patients, 33%) with documentation of LVAs. There was no statistical difference in the BMI between the two groups (29.9 ± 4.9 in patients with PVI only vs 29.0 ± 4.8 in patients with PVI + substrate modification; p=0.37). Furthermore, in a subgroup analysis of only adipose patients with a BMI higher than 30 (44 patients; 48%; mean BMI 33.8 ± 3.0), there was no significant difference in BMI between the two groups (34.2 ± 3.3 in PVI only vs 33.2 ± 2.4 in patients with PVI and substrate modification; p=0.2) Discussion and conclusion Even though a high BMI is generally related to a higher incidence of AF, a higher BMI was not observed in patients having additional low-voltage areas in LA compared to patients in whom such areas could not be identified. Electric remodeling caused by obesity could be rather diffuse than localized in specific areas in LA. BMI is not a pre-procedural marker for the presence of additional low voltage areas in LA.

P1892Asymmetric and symmetric dimethylarginine in atrial fibrillation progression and recurrence

The novel P-Wave Area index predicts low voltage areas in patients undergoing pulmonary vein isolation for treatment of atrial fibrillation

Presence of low voltage area predicts atrial tachyarrhythmia inducibility with atrial burst pacing after pulmonary vein isolation

Background: Low voltage areas (LVAs) in the left atrium (LA) are associated with a higher likelihood of non-pulmonary vein triggers for atrial fibrillation (AF), and ablation of LVAs has been shown to reduce AF recurrence. This study aimed to assess the distribution and predictors of LVAs in a large cohort of patients undergoing AF ablation. Methods: This study included patients who underwent first AF ablation at the Hospital of the University of Pennsylvania between November 2020 and December 2022. Patients with prior LA ablation, cardiac surgery, sarcoidosis, or amyloidosis were excluded. All patients underwent voltage mapping with multipolar mapping catheters and pulmonary vein isolation. LVAs were defined as contiguous areas with a bipolar voltage &lt;0.5mV. The associations between preprocedure risk factors, echocardiographic findings, and LVAs were assessed using univariable logistic regression. All variables with a p value &lt;0.1 were entered in a stepwise, backward, multivariable model. Results: A total of 857 consecutive patients (mean age: 64.7 years, 34% women, 33% non-paroxysmal AF) were included. LVAs were identified in 132 (15.4%) patients, of whom 72% had LVAs in posterior wall, 47.7% in roof/anterior, 43.9% in septum, 24.2% in floor/inferior, and 16.7% in lateral wall. The multivariable model showed that age (OR per 1 year increase 1.05, 95% CI 1.03-1.08), heart failure/left ventricular cardiomyopathy (OR 2.1, 95% CI 1.4-3.3), sinus node dysfunction (OR 3.7, 95% CI 1.8-7.3), persistent/permanent AF (OR 3.2, 95% CI 2.1-4.9), and severe LA enlargement on echocardiography (OR 1.9, 95% CI 1.1-3.5) were independent predictors of LVAs. Conclusion: LVAs are identified in 15% of patients undergoing first AF ablation and are typically located along the posterior and anteroseptal LA. Presence of LVAs can be anticipated using a readily available preprocedure risk assessment. This information may influence preprocedure planning and choice of ablation strategy.

POSTER PRESENTATIONS

Background With regard to the recurrence rate after ablation, estimation of the extent of left atrial (LA) fibrosis is essential for planning the best treatment of persistent atrial fibrillation (AF). Currently, the only invasive measure available is electroanatomical mapping. The MRI examination is not yet sufficiently groundbreaking. Non-invasive tools provide tendencies for estimating fibrosis, but there is no summarizing score system so far. Purpose The aim of the study was to combine non-invasive tools to provide a better assessment of LA fibrosis. Methods Patients with persistent AF were examined using contrast-enhanced atrial-CT, TTE including LA strain and comprehensive P-wave analysis in sinus rhythm. Prior to ablation, electroanatomical mapping was performed in sinus rhythm if possible. Results Of the included patients, 19 of 90 (21%) patients had LA fibrosis defined as &amp;gt;10% low voltage area (LVA). Seven of these patients received substrate modification in addition to PVI. These patients were older (66 vs 69 years) and woman are more likely to have LVA (20% vs 47%). Neither pre-existing conditions nor LA characteristics from CT and TTE showed a correlation with the presence of LVA. Of the established P-wave parameters, only the P-wave voltage in lead I showed differences in the groups (0.05 mV vs 0.03 mV). It was striking that there were many patients with LVA&amp;lt;10% who nevertheless received substrate modification. These observations can be explained by the isolated LVA in the anterior and roof areas. After a more detailed analysis, 34 (37%) of the patients in the total cohort had LVA anterior and roof of &amp;gt;10% and 17 of these patients received substrate modification. In comparison, these patients are older (65 vs 69 years), female, have a larger atrium (LAVI 77 vs 86 ml/m²) and a worse LA strain (20 vs 14%). They are more likely to have COPD, renal insufficiency and at least moderate valve disease. Also in this group, only the voltage of the P-wave in lead I is associated with the extent of LVA anterior and roof. Interestinglythese patients have less tachycardia- induced myopathy compared to the global LA fibrosis group. Discussion In the subgroup of patients with persistent atrial fibrillation, characteristics from CT, TTE and ECG do not appear to be suitable for predicting global LA fibrosis. However, the LVA in the anterior and roof regions are particularly relevant with regard to necessary substrate modification. In this subgroup we see trends in some non-invasive parameters.

Research Needs and Priorities for Catheter Ablation of Atrial Fibrillation

Characterization of Low-Voltage Areas in Patients With Atrial Fibrillation: Insights From High-Density Intracardiac Mapping

Introduction Atrial fibrosis plays a significant role in the development of atrial arrhythmias, both in atrial fibrillation (AF) and atypical (left) atrial flutter (AAFL). While predisposing factors for AF and AAFL somewhat overlap, the differences in the substrate are still not well known. Low voltage areas (LVA), assessed using bipolar voltage mapping, are considered a surrogate for local fibrosis. In this study, we used LVA quantification in order to compare the amount of atrial fibrosis in patients with persistent AF and AAFL. Purpose To examine whether AAFL patients would have a higher percentage of atrial fibrosis than Persistent AF patients, representing a more complex fibrotic substrate. Methods This retrospective single-center study included consecutive patients who underwent ablation for AF and AAFL using the Biosense Webster CARTO mapping system from 2023 to 2024 and had bipolar voltage maps amenable to analysis. Measurements of very low voltage (0-0.2mv), low voltage (0-0.5mv), and normal (&amp;gt;0.5mv) areas were made using the CARTONET's (Biosense Webster) voltage histogram. Detailed voltage analysis was performed for the entire left atrium and specifically segmented for anterior and posterior walls. Statistical comparisons were conducted using the Mann-Whitney U test. Results Twenty AF patients and twelve AAFL patients were included in the study. The mean age was 70 and 67 in the AF and AAFL groups. Rate of left atrial enlargement (moderate or higher) was 61% and 54.5%, respectively. Preserved left ventricular systolic function rate was 65% and 83%, respectively. Mean low voltage and very-low voltage areas were significantly higher in AAFL, comparing AF with 6041.66mm2 vs. 2928.25mm2 (p=0.0005) and 3299.12mm2 vs. 1163.42mm2 (p=0.0003) respectively. The percentage of low-voltage and very-low-voltage areas was 52.63% and 28.64% in the AAFL group and 24.16% and 9.33% in the AF group (p=0.0007, p=0.0001, respectively). Significantly larger low and very low-voltage areas were also measured in a separated analysis of the anterior and posterior walls. Conclusion AAFL is associated with significantly more extensive areas of atrial fibrosis, represented by left atrial LVA, compared to persistent AF. This finding may represent a more progressive atrial disease in AAFL patients, and suggest the higher involvement of additional, non-fibrotic mechanisms in persistent AF.Table 1.Measurements of low-voltage area Figure 1.Voltage Map. A – AAFL; B - AF

Funding AcknowledgementsType of funding sources: None.BACKROUNDLeft atrium (LA) fibrosis has been shown to be an important factor associated with atrial fibrillation recurrence after catheter ablation (CA). Morphological features of the P wave have been related to the extent of atrial fibrosis as identified with electroanatomic mapping (EAM) in patients with paroxysmal atrial fibrillation (PAF) undergoing catheter ablation (CA). The ability to assess, by means of non-invasive markers, the electroanatomical substrate of the LA and the likelihood of PAF recurrence after CA, could be very useful in PAF management, patient selection for CA and improving outcomes.PurposeIn the current prospective cohort study we aimed at establishing a pathophysiological basis of beat-to-beat (B2B) P-wave morphological and wavelet analysis, showing that it is associated with areas of considerable fibrosis, as identified with EAM in patients with PAF.Methods44 patients with symptomatic paroxysmal AF, diagnosed at least 6 months before, were enrolled. 12-lead electrocardiogram (ECG) recordings, as well as 12 min vectorcardiogram (VCG) recordings were obtained from all patients, while EAM of left atrium (LA) was performed in all patients before radiofrequency CA. B2B P-wave morphological and wavelet analysis was performed according to a methodology described in previous publications.ResultsThe 35 patients who were valid for statistical analysis were divided into 2 groups: in Group A the total low-voltage (<0.5 mV in EAM) area was greater than the median value of 5.55% (large low-voltage area), while in Group B the total low-voltage area was <5.55% (small low-voltage area). From the correlation between standard P-wave indices derived from 12-lead ECG and low-voltage areas only P-wave duration was significantly different between the two groups. From orthogonal ECG parameters analysis X axis was the most representative of low-voltage areas. B2B P-wave analysis revealed 3 features which showed a statistically significant difference between the 2 groups and no collinearity (Table 1). Logistic regression analysis of the non correlated variables for the prediction of low-voltage areas is shown in Table 2. It seems that a longer distance between the P-wave peak and the P-wave end, as well as a more «flattened» P-wave (small area with long duration) is associated with larger low-voltage areas and consequently more extensive LA fibrosis.ConclusionsIn patients with PAF and no overt atrial myopathy, B2B wavelet analysis may be a useful non-invasive tool for the prediction of low-voltage areas, representing fibrosis in the LA. Further studies in larger cohorts of patients are needed in order to confirm these findings and enable the use of B2B wavelet analysis in clinical practice.

Long-term prognosis in patients undergoing atrial fibrillation ablation