Low-voltage Areas Research Articles

Abstract 4124323: Extensive atrial cardiomyopathy indicated by left atrial low-voltage areas predicts subsequent stroke after atrial fibrillation ablation

Background: Atrial fibrillation (AF) is a leading cause of stroke. However, predictors of stroke after AF ablation have not been well clarified, therefore, evidences of anticoagulation therapy after the procedure have been limited. Although left atrial low-voltage areas (LVAs) reflects atrial cardiomyopathy, which is a potential cause of thromboembolism, there are few reports of an association between LVAs and stroke. The purpose of this study was to investigate the association between atrial cardiomyopathy assessed by LVAs and stroke in patients undergoing AF ablation. Methods: The study design was a single center, retrospective observational study. This study included 1,486 (age, 68 ± 10 years; female, 501 [34%]; persistent AF, 905 [61%]) consecutive patients who underwent initial AF ablation from December 2014 to March 2022. The definition of LVAs were areas with a bipolar voltage of <0.5 mV in the left atrium. The area of LVAs in the whole left atrium was divided into 3 groups, namely <5cm 2 , 5-20 cm 2 and ≥20 cm 2 . Stroke after AF ablation was followed for 60 months. Results: Of 1,486 patients, LVAs were found in 352 (24%) patients, and 25 (1.7%) patients developed stroke (hemorrhagic stroke, 4 [16%] patients; ischemic stroke 21 [84%] patients). Freedom from stroke was significantly lower in patients with LVAs than in those without (<5cm 2 : 98.3%, 5-20 cm 2 : 95.4%, ≥20 cm 2 : 88.8%, p<0.001). Additionally, LVAs ≥20 cm 2 was an independent predictor of the development of stroke after AF ablation (hazard ratio 4.9, 95% confidence interval: 2.0-12; p=0.001, adjusted by estimated glomerular filtration rate and AF recurrence after ablation). Conclusion: In patients with initial AF ablation, freedom from stroke after AF ablation was significantly lower in patients with LVAs ≥20 cm 2 than in patients with LVAs 5-20 cm 2 and in patients with LVAs <5cm 2 . Particularly, LVAs ≥20 cm 2 was an independent predictor of the development of stroke after AF ablation.

Abstract 4138733: Predictive Value of Serum Vasoactive Intestinal Peptide for Low-Voltage Areas in Atrial Fibrillation

Introduction: Identifying low-voltage areas (LVAs) within left atrium (LA) is crucial for predicting atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI). Animal studies have shown that the parasympathetic neurotransmitter vasoactive intestinal peptide (VIP) affects atrial electrophysiological remodeling. Hypothesis: Thus, we hypothesized that elevated serum VIP levels might contribute to the development of LVAs and that serum VIP concentrations could serve as a biomarker for LVA presence in AF patients. Aims: The aim of this study is to investigate the relationship between the blood levels of VIP and the presence of LVAs in AF patients with electroanatomical mapping (EAM). Methods: We conducted an observational, prospective cross-sectional study on AF patients undergoing PVI between 2021 and 2023. Blood samples for VIP were collected before atrial septal puncture, and EAM was performed using CARTO 3® before PVI. VIP concentrations were measured using an enzyme-linked immunosorbent assay kit. Patients were divided into two groups based on LVA presence (≥5% or <5%) as determined by EAM. Results: Among the 108 patients, 51 (47%) had LVA. VIP levels were significantly higher in patients with LVA compared to those without (median [interquartile range]: 335.1 [274.1-456.5] pg/mL vs. 247.7 [196.1-294.0] pg/mL, p<0.001). No difference was observed in VIP levels by LVA sites. Multivariate logistic regression identified VIP and sex as independent predictors of LVA (per 50 pg/mL, odds ratio [OR]: 1.44, 95% confidence interval [CI]: 1.13-1.83, p<0.001, OR: 4.67, 95% CI: 1.69-12.89, p=0.002, respectively). Females with high VIP had lower conduction velocity compared to other groups. (low VIP male: 0.9 [0.6-1.0] m/s, high VIP male: 0.9 [0.7-1.1] m/s, low VIP female: 0.8 [0.7-1.0] m/s, high VIP female: 0.7 [0.3-0.8] m/s, p=0.013). Incorporating VIP levels (≥288 pg/mL) into an existing predictive score (age ≥65 years, female, and LA volume index ≥57 mL/m 2 ) significantly improved LVA detection (area under the curve: 0.784 vs. 0.707, p<0.001). Conclusions: Serum VIP levels are higher in patients with LVAs, and VIP is a reliable predictor of LVA presence. Incorporating VIP levels into existing predictive models enhances the power for identifying LVAs in AF patients. Serum VIP measurement could be valuable for detecting LVAs, improving risk stratification, and tailoring strategies in AF management.

Abstract 4140117: A novel risk score predicts the prevalence of left atrial low-voltage areas and rhythm outcome in patients undergoing long-standing persistent atrial fibrillation ablation

Background: Catheter ablation is a most common treatment for atrial fibrillation (AF), but rhythm outcome after AF ablation in long-standing persistent atrial fibrillation (LS-PerAF) is still poor. Left atrial low-voltage areas (LVAs) is associated with poor rhythm outcome after catheter ablation. However, the predictors of LVAs presence have not been fully elucidated in patients with LS-PerAF. Purpose: The purpose of this study was to establish a novel predictive score for the prevalence of LVAs in patients with LS-PerAF ablation. Methods: In total, 109 consecutive patients who underwent initial ablation for LS-PerAF were included. LS-PerAF was defined as AF whose duration was more than 1 year. LVA was defined as areas with bipolar peak-to-peak voltage of < 0.50mV. A clinical risk score was obtained as the total number of independent predictors analyzed by multivariate logistic regression analysis. AF recurrence after the catheter ablation was followed for 24 months. Results: Of 109 patients with LS-PerAF, LVAs existed in 26 (24%) patients. A novel predictive score, named DESK score, consisted of diabetes mellitus (odds ratio [OR] 3.7, [95% confidence interval {CI} 2.2–11], p = 0.02), age ≥ 70 years (OR 3.8, [95% CI 1.4-10], p = 0.007), female sex (3.0 [95% CI 1.04-8.4], p = 0.04), AF duration ≥ 3.7 years (44 months) (OR 3.7, [95% CI 1.3-11], p =0.02). LVAs were more frequently found in patients with a higher DESK score (OR, 3.5 [95% CI, 1.9–6.5], p < 0.001) (Figure 1A). On receiver operating characteristic curve analysis, DESK score was a moderate predictor of LVAs presence (area under the curve, 0.750; Figure 1B). The optimal cut-off of DESK score was 3 points, corresponding to a 38.5% sensitivity, 97.6% specificity, and 83.5% predictive accuracy. Freedom from AF recurrence was significantly lower in patients with DESK score ≥ 3 than in those with DESK score < 3 (10.4% vs. 43.5%, p = 0.008). Conclusions: In patients who underwent LS-PerAF ablation, the DESK score correlated with the prevalence of LVAs, and associated with poor rhythm outcome.

Abstract 4141438: Predictors of Left Atrial Low Voltage Areas Were Different among Age Groups in Patients with Atrial Fibrillation Ablation

Background: Catheter ablation is a well-established treatment for atrial fibrillation (AF). Left atrial low-voltage areas (LVAs) is associated with atrial remodeling following the progression of atrial cardiomyopathy, and poor rhythm outcome after catheter ablation. However, the predictors of LVAs presence have not been fully elucidated in different age groups. Purpose: The purpose of this study was to investigate predictors of the prevalence of LVAs in different age groups. Methods: 1,488 (age, 69 ± 10 years; female, 501 [34%]) consecutive patients who underwent initial ablation were included. Age groups were divided into three groups, namely <60 years old (younger age, n=272), 60-75 years old (intermediate age, n=864), ≥75 years old (older age, n=352). The definition of LVAs was areas with a bipolar voltage of <0.5 mV covering ≥5 cm2 of left atrial surface. Multivariate logistic regression analysis was performed to investigate the clinical predictors of LVAs. Results: Of 1,488 patients, LVAs existed in 352 (24%) patients. In the younger age group, C-reactive protein (odds ratio [OR], 4.5; [95% confidence interval {CI}: 1.5-13], p = 0.006) and previous history of heart failure (OR, 5.6; [95% CI: 1.2-26], p = 0.027) were the independent predictors of LVAs. In the intermediate age group, female (OR, 3.8; [95% CI: 2.6-5.7], p < 0.001), persistent AF (OR, 2.6; [95% CI: 1.7-4.1], p < 0.001), lower body mass index (OR, 0.93; [95% CI: 0.88-0.98], p = 0.004), lower hemoglobin (OR, 0.81; [95% CI: 0.72-0.93], p = 0.002), C-reactive protein (OR, 1.4; [95% CI: 1.0 1-2.0], p = 0.047), diabetes mellitus (OR, 1.8; [95% CI: 1.1-2,8], p = 0.01), left atrial diameter (OR, 1.04; [95% CI: 1.01-1.1], p = 0.007) were the independent predictors of LVAs. In the older age group, female (OR, 2.3; [95% CI: 1.4-3.7], p = 0.01), persistent AF (OR, 3.1; [95% CI: 1.8-5.2], p < 0.001) and lower hemoglobin (OR, 0.83; [95% CI: 0.71-0.97], p = 0.017) were the independent predictors of LVAs. Conclusion: In patients with atrial fibrillation ablation, the independent predictors of LVAs were different among age groups.

Left Atrial Structure and Function Following Ethanol Infusion into Vein of Marshall (MR-SHALL Study).

Ethanol infusion into the vein of Marshall (EI-VOM) is an adjunctive therapy to pulmonary vein isolation (PVI), which improves the efficacy of persistent atrial fibrillation (AF) ablation procedures. It is unknown how EI-VOM scar formation impacts left atrium (LA) structure and function. To characterize scar formation after EI-VOM, and its impact on LA function, by cardiac magnetic resonance (CMR). Consecutive patients referred for persistent AF ablation, or any repeat procedure, were included. Ablation strategy included PVI, EI-VOM and linear lesions when deemed necessary. LA was assessed by late gadolinium enhancement (LGE) CMR at baseline and 3-month follow-up. CMR was post-processed off-line with dedicated software. The LA was regionalized into 17 segments, and global and regional scarring were calculated. Strain parameters were analyzed-including LA reservoir, conduit, and booster strain; LA ejection fraction; and LA passive and active emptying function. Follow-up LGE-CMR reconstruction was coregistered with the voltage map, ablation RF points, and fluoroscopy to compare the scar location with the VOM trajectory. This study included 21 patients (65 ± 8 years; 76% men; 57% ablation of persistent AF). After EI-VOM, 95% of patients presented new low-voltage areas, all of whom exhibited new LGE-CMR scarring at follow-up. Voltage map and LGE-CMR coregistration showed comparable scar areas (p = 0.287). LGE-CMR scarring frequently involved the whole VOM trajectory, predominantly affecting the LA ridge, mitral isthmus, and left posterior wall. LA volume was significantly reduced after ablation, without significant changes in LA functional parameters. EI-VOM causes permanent scarring at 3-month follow-up, with no adverse impact on CMR LA functional parameters.

β-Hydroxybutyrate and Citrate Synthase as Potential Diagnostic Biomarkers in Aging-Related Atrial Fibrillation.

The incidence of atrial fibrillation (AF) increases with age; however, the precise mechanisms by which aging elevates AF risk and the effective biomarkers for managing AF in elderly patients remain unclear. We analyzed plasma samples from 100 elderly AF patients, 100 young and 100 elderly patients without atrial fibrillation (NAF), along with left atrial tissues obtained from both AF and NAF patients following valve replacement. Our findings indicate reduced levels of β-OHB and citrate synthase (CS) activity in elderly AF patients compared to their NAF counterparts. Statistical analysis revealed a protective association between β-OHB and CS activity concerning the occurrence of elderly AF. Furthermore, atrial tissues from elderly AF patients exhibited mitochondrial dysfunction, structural remodeling, and low-voltage areas. These results suggest that dysregulation of β-OHB levels and CS activity may contribute to aging-related AF by affecting mitochondrial function and atrial remodeling, highlighting their potential as diagnostic biomarkers for this condition.

Unipolar electroanatomical mapping outperforms bipolar voltage in detecting LGE areas in the left atrium

Abstract Introduction In atrial fibrillation (AF) management, understanding left atrial substrate is crucial. While both electroanatomical mapping (EAM) and late gadolinium enhancement MRI (LGE MRI) are reliable methods in assessing atrial substrate and are associated with the ablation outcome, recent findings have highlighted significant discrepancies between bipolar low voltage areas (LVA) in EAM and LGE areas. Objective Explore the relationship between LGE areas and unipolar LVAs by utilizing multipolar high-density (HD) mapping. Methods Nineteen patients scheduled for AF ablation underwent pre-ablation LGE-MRI. Left atrial (LA) segmentation was conducted using a convolutional neural network, which subsequently generated a 3D mesh integrating the LGE data. HD-EAM was performed in sinus rhythm for each patient, capturing at least 4000 points. The EAM map and LGE MRI mesh were co-registered. LVA areas were defined using voltage cut-offs of 0.5 mV for bipolar and 2.5 mV for unipolar measurements. Correspondence between LGE areas and LVAs on the anterior and posterior LA wall was analyzed. Results Both bipolar and unipolar LVA demonstrated high precision in detecting LGE areas (100% and 88% respectively). However, unipolar LVA exhibited a remarkable accuracy of 81% for detecting LGE areas specifically, whereas bipolar LVA displayed a significantly lower accuracy of 28%. These findings were consistent across the different atrial walls. Conclusion Incorporating unipolar voltage data into electroanatomical mapping in the atrium may bridge the observed gap between LGE areas and bipolar LVAs. Our findings highlight the significance of unipolar voltage in evaluating the left atrial substrate, potentially offering a more comprehensive insight into the different layers of atrial walls, and opening the door for new approaches in AF therapy.

Impact of left atrial stiffness measurement as a pre-procedural predictor of an extensive left atrial low-voltage area

Abstract Background The presence of a left atrial (LA) low-voltage area (LVA) after pulmonary vein isolation for atrial fibrillation (AF) is a strong predictor of recurrence and LVAs are often an additional ablation target. However, predicting the presence of an LVA before the procedure remains challenging. Purpose To assess the LA stiffness index as a preprocedural predictor of an extensive LVA. Methods We prospectively evaluated 74 patients who underwent catheter ablation for AF and high-density bipolar LA voltage mapping during sinus rhythm or high right atrial pacing. "LVA" was defined as an area with bipolar electrograms (<0.5 mV), while "extensive LVA" was defined as the presence of an LVA that covered more than 15% of the LA surface. Echocardiographic measurements, including the LA volume index (LAVi), E/e' ratio, LA reservoir strain (LASr), and LA stiffness index, calculated as the ratio of E/eʹ to LASr, were performed prior to catheter ablation in all patients. Results Overall, 17 patients (23.0%) had an extensive LVA. Patients with extensive LVAs were older (73 ± 7 vs. 66 ± 8 years; P=0.003), predominantly female (59% vs. 23%; P=0.01), and more frequently showed persistent AF (59% vs. 30%; P=0.04) in comparison to patients without extensive LVAs. According to a receiver operating characteristic curve analysis, the LA stiffness index was more accurate than the LAVi or LASr for predicting extensive LVAs (Figure), allowing using a cutoff value ≥0.6 with 73% sensitivity and 91% specificity. A multivariate logistic regression analysis revealed that the LA stiffness index was an independent predictor of an extensive LVA (odds ratio [OR], 44.11; 95% CI 3.83–507.47, P=0.002). Conclusion The LA stiffness index was a robust predictor of the extent of LVAs in AF patients and thus could be useful for the preprocedural selection of candidates for catheter ablation and to determine the most effective ablation strategies.

Severity of anemia is correlated with the prevalence of left atrial low-voltage areas in patients with atrial fibrillation ablation

Abstract Background Although left atrial low-voltage areas (LVAs) are well-known indicator of atrial fibrosis and atrial fibrillation (AF) recurrence after catheter ablation, the association between anemia and prevalence of LVAs has not been clarified. We hypothesized that LVAs were more frequently found in patients with anemia than in those with normal hemoglobin levels. Purpose The purpose of this study was to investigate the association between hemoglobin levels and the prevalence of LVAs in patients with AF ablation. Methods In total, 1,473 (age, 68±10 years; female, 492 [33%]; persistent AF, 895 [61%]; CHA2DS2-VASc score, 2.5±1.5 points) consecutive patients who underwent initial AF ablation were enrolled in this study. Hemoglobin levels were measured before the ablation procedure, and anemia was defined as hemoglobin levels < 13.5 g/dL in male and < 12.0 g/dL in female. LVAs was defined as areas with bipolar voltage of <0.5 mV covered ≥5 cm² of left atrial surface area. Results Of 1,473 patients, LVAs existed in 348 (24%) patients. Hemoglobin levels was significantly lower in patients with LVAs than those without (13.4 ± 1.7 vs. 14.2 ± 1.5 g/dL, p <0.001). On classification by gender, only in male, hemoglobin levels were significantly lower in patients with LVAs than those without (Figure 1). The prevalence of LVAs increased with decreasing hemoglobin levels (Figure 2). On multivariate analysis including gender as a variable, anemia was an independent predictor of LVAs (odds ratio, 1.6; 95% confidence interval: 1.1–2.3; p=0.03). Conclusions The prevalence of LVAs increased with decreasing hemoglobin levels in patients with AF ablation. In particular, hemoglobin levels < 13.5 g/dL in male and < 12.0 g/dL in female was an independent predictor of LVA presence.Hemoglobin levels and LVAs presenceHemoglobin and the prevalence of LVAs

Long-term prognosis in patients undergoing atrial fibrillation ablation

Abstract Aims The aim of the analysis was to assess the risk of atrial fibrillation (AF) recurrence in the long-term observation of contemporary patients undergoing pulmonary vein isolation (PVI), who did not have recurrence during the first year after catheter ablation. Methods Retrospective analysis has been performed. Inclusion criteria: (1) the patients undergoing their first PVI in years 2017–2022, (2) the electroanatomical system, contact force catheters and lesion indexes (Ablation Index or Lesion Size Index) were used, (3) no recurrences were observed during the first 12 months of follow-up, and (4) follow-up longer than 12 months was available. Demographic, clinical and echocardiographic data were collected. Follow-up was based on ambulatory visits with ECG/holter monitoring or implanted device interrogation, when available. Results A total of 247 patients were included. The median follow-up was 22 months (interquartile range, 16–31 months). After 24 months, ablation efficacy was 84%, and after 36 months, it was 72%. In the univariate Cox regression analysis, age, previous electrical cardioversion, glomerular filtration rate (eGFR) and the presence of coronary artery disease were linked to AF-free survival. Interestingly, nonparoxysmal AF, left atrial (LA) dimension, heart failure, hypertension or diabetes were not linked to the risk of long-term recurrences. In multivariate Cox regression analysis, presence of coronary artery disease and previous electrical cardioversion were independently linked to the risk of long-term recurrence. In 127 (51.4%) patients, information about the presence of low voltage areas (LVA) was available, and in 21 (16.5%) patients in this group, the presence of LVA was found. Survival of patients with LVA was strikingly worse than that of those without (Figure 1), log-rank test p <0.0001. Conclusions Patients who had no recurrences within one year after PVI, still have substantial risk of recurrence in the next 2 years. That concerns specially the patients who had LVA in the electroanatomical mapping.

Novel approach of slow pathway ablation in common atrioventricular nodal reentrant tachycardia by peak frequency map

Abstract Background It is difficult to visualize slow pathway in atrioventricular nodal reentrant tachycardia (AVNRT) even with recent high-density mapping. This could be because the slow pathway potential is buried by the potential of atrial working cells during sinus rhythm and tachycardia. In other words, it is extremely difficult for conventional 3D mapping systems to annotate slow pathway potential even though the histological run of slow pathway is known .[1], [2] Purpose The purpose of this study is to visualize the atrial myocardial junction of rightward inferior extension by the peak frequency map of Ensite X in common AVNRT and to evaluate whether relative high frequency (HF) sites in low voltage area extending from Koch's triangle to tricuspid annulus (TA) is effective targets of slow pathway ablation and the characteristics of junctional rhythm (JR) after radiofrequency application. Methods This study is single-center prospective cohort study. In 37 consecutive common AVNRT patients, novel approach and conventional approach of slow pathway ablation were performed in 17 and 20 patients, respectively. The conventional approach is anatomical and electrophysiological approach. Peak frequency map was performed during sinus rhythm with HD-grid catheter in novel approach patients. A frequency scanning is performed to locate relative HF sites on the tricuspid annulus. Radiofrequencey application is 30 W, 30-60 sec, and the end point was no inducibility or until one echo under load of isoproterenol. Results The success rate was 100 % with two approaches. The relative HF sites in low voltage area were distributed at the TA side from 4 to 5 o'clock in all novel approach patients, mean peak frequency in success site was 419 ± 87 Hz. The distance to His bundle from success site was farther (24.8 ± 4.9 vs. 12.8 ± 4.4 mm, p<0.001), JR was slower (93 ± 14 vs. 118 ± 10 bpm, p=0.013), time to JR occurrence was shorter (3.0 ± 1.3 vs. 7.6 ± 4.6 sec, p=0.003), and elimination rate of jump up (78 % vs. 40 %, p=0.06) was higher in novel approach. Conclusions The relative HF sites in low voltage area at TA side from 4 to 5 o'clock by peak frequency map could be novel target of slow pathway ablation with high success rate and sufficient safety and efficiency.peak frequency map

Exploring LGE areas in the atria: Insights from electroanatomical voltage mapping in AF patients

Abstract Introduction Late gadolinium enhancement MRI (LGE MRI) is a common method for the evaluation of the atrial substrate in atrial fibrillation (AF) patients. The extent of LGE is associated with atrial cardiomyopathy and ablation outcomes. However, previous studies have yielded inconsistent results in detecting low voltage areas (LVA) using bipolar electroanatomical mapping (EAM) in LGE regions. Objective Conduct a thorough analysis of the bipolar and unipolar voltage in LGE areas and its relationship with the voltage in non-LGE areas, utilizing high-density (HD) EAM generated by a multipolar HD-mapping catheter. Methods In this study, 20 patients undergoing AF ablation were examined using LGE-MRI. A 3D mesh integrating LGE data was generated. HD-EAM (> 4000 points) was performed in sinus rhythm. The EAM map and MRI mesh underwent manual alignment and registration. Using a nearest neighbor algorithm, EAM points nearest to LGE areas were identified, and the corresponding unipolar and bipolar voltage values, along with LGE voxel intensity, were exported for analysis. Results LGE areas exhibited a median bipolar voltage amplitude of 0.93 mV, median unipolar voltage of 1.73 mV. In contrast, areas without enhancement displayed median bipolar voltage of 2.33 mV, unipolar voltage of 3.58 mV. We observed a variation in voltage amplitudes across the different LGE areas: bipolar voltage ranged from 0.04 to 2.51 mV and unipolar voltage from 0.22 to 3.75 mV. This variation strongly correlated with voxel intensity in LGE areas (correlation coefficient r = -0.86 [p <0.001]). Irrespective of the voltage amplitude in the examined LGE areas, a significant voltage drop was observed, with an average reduction of 54% in bipolar and 51% in unipolar voltages, compared to the amplitudes in non-LGE areas within the same atria. Conclusion Variations in bipolar and unipolar voltage within LGE areas are significantly correlated with local voxel intensity. Despite the inconsistent overlap with the predefined bipolar threshold for LVA, LGE regions exhibit a pronounced and consistent reduction in both bipolar and unipolar voltage compared to non-LGE areas. This pattern suggests notable electrophysiological changes in these areas. These insights underscore the need for further investigation to better understand the implications and mechanisms underlying these alterations in LGE regions.

Right atrial strain: the hidden proof of bi-atrial cardiomyopathy in AF patients?

Abstract Background Although assessment of left atrium (LA) abnormalities has been extensively studied in atrial fibrillation (AF), structural and functional changes in the right atrium (RA) have remained almost unexplored in this context. Purpose We investigated the role of bi-atrial strain in patients with AF undergoing catheter ablation (CA). Methods Fifty-six consecutive patients undergoing catheter ablation of AF were prospectively studied with speckle-tracking echocardiography and electrophysiological study, before and after CA (median follow-up: 7±3 months). A group of 32 subjects undergoing CA of paroxysmal atrioventricular node-reentrant tachycardia, without structural heart disease, served as control group. Results Patients with AF had worse LA, but also RA strain indexes compared to controls [RA strain parameters: peak RAS reservoir (pRASr): 22.1±12.6 vs 29.8±12.7%, p=0.009; RA dispersion: SD-regional-RA-time-to-peak (SD-regional-RA-TTP): 0.048±0.015 vs 0.038±0.009, p=0.020)]. Patients with persistent AF showed similar LA strain values, but worse RA strain indexes, compared to patients with paroxysmal AF (pRASr: 24.8±12.1 vs 15.9±11.7%,p=0.017; SD-regional-RA-TTP:0.043±0.023 vs 0.062±0.030, p=0.016). RA function showed a significant relation with both LA strain and volume indexes and with abnormal LA electroanatomical substrate (pRASr and pLASr, Pearson correlation: r 0.594, p< 0.001; pRASr and low-voltage LA area: -0.316, p=0.018). RA, but not LA, parameters were found significantly reduced in patients with AF recurrence post-CA compared to those who maintain sinus rhythm (pRASr: 14.1±11.7 vs 24.6±13.5, p=0.039; SD-regional-RA-TTP: 0.054±0.031 vs 0.032±0.010, p=0.002), while the only independent clinical predictor of AF recurrence remained cardiovascular risk profile (CHA2DS2 VASc Score: HR 1.47,CI 1.003-2.158, p= 0.048). Conclusion RA function, as assessed by strain imaging, resulted progressively impaired in worse subtypes of AF, showing a strong correlation with bi-atrial mechanical and electroanatomical parameters, and associated with AF recurrences post-ablation.Graphical Abstract

Atrial function after cardioversion in patients with persistent atrial fibrillation

Abstract Background After cardioversion for persistent atrial fibrillation (AF), restitution of normal left atrial (LA) function is said to need several days to recover. However, in previous studies, the evaluation of LA function was only used transesophageal or transthoracic echocardiography. During catheter ablation (CA) for AF, pulmonary venous (PV) blood flow can be measured accurately using an intracardiac echocardiogram (ICE). The atrial systolic PV regurgitation (PVa) wave measured by ICE is a good indicator of LA contractility because it reflects the active contraction of the LA. Purpose This study aims to investigate the LA function in the hyperacute phase and the factors which affect after cardioversion. Methods 40 AF patients (18 paroxysmal AF, 22 persistent AF) who underwent CA were enrolled. PVa wave was measured twice before RFCA and after the procedure using intracardiac ultrasound. Voltage map of the LV was obtained using the CARTO system at the end of the session, and the percentage of low voltage area which was determined area as less than 0.1mV in the mapped LA surface area (LVA%) was calculated. Results Preoperative PVa was 1.61 ± 0.09 m/sec in the paroxysmal AF group (PaAF), and no PVa was observed in the persistent AF group (PeAF). Postoperative PVa were comparable between PaAF (0.18±0.06 m/sec) and PeAF (0.18±0.07 m/sec). Then, the PeAF were divided into 2 groups based on LVA% in the anterior area, posterior area, and total LA area (cutoff 1,5 and 10%, respectively). In the anterior lower LVA% group, PVa were significantly increased (0.20 ± 0.07 m/sec) after defibrillation compared with the anterior higher LVA% group (0.14 ± 0.06 m/sec; P=0.02), whilst no difference was observed when it was divided in the posterior wall or overall. Conclusion Even in PeAF, LA function improves to the same degree as in the PaAF immediately after cardioversion, and the posterior wall LVA, including posterior wall isolation, may not affect LA function.

High-Density and Resolution Epicardial Mapping of the Atria: Translational Research with Clinical Impact.

The electrical arrhythmogenic substrate underlying the most common cardiac arrhythmia atrial fibrillation (AF) may consist of conduction disorders, low-voltage areas, or fractionated potentials. High-density and resolution epicardial mapping (HDREM) approaches have been introduced to quantify and visualize electrophysiological properties of the atria. These approaches are essential for obtaining innovative insights into arrhythmogenic substrates and identifying novel targets for therapy. The aim of this review is to summarize and discuss the (1) contribution of HDREM studies to the knowledge on atrial arrhythmogenesis and (2) future applications of HDREM of atria in daily clinical practice.

Left Atrial Low-Voltage Extent Predicts the Recurrence of Supraventricular Arrhythmias.

The incidence of left atrial (LA) supraventricular arrhythmias is increasing. Even after LA ablation, recurrence of these tachycardias is common. MRI studies show that LA cardiomyopathy is a significant risk factor for recurrence and correlates with low voltage areas detected via 3D electroanatomic mapping (EAM). There are limited data on the impact of low voltage extent detected by EAM on recurrence-free survival. Voltage thresholds defining low voltage vary across different studies. This study aims to investigate the impact of the extent of low voltage areas in the LA on recurrence-free survival and to assess whether defining low voltage areas using thresholds of 0.5, 0.4, or 0.3 mV offers better predictive performance. Patients with atrial arrhythmia who underwent LA EAM at Ulm University Heart Center between September 2018 and September 2022 were included from the ATRIUM registry. ROC analysis determined the voltage threshold for predicting recurrence-free survival. Kaplan-Meier and logistic regression models adjusted for patient variables were used to analyze recurrence-free survival. Of 1089 screened patients, 108 met the inclusion criteria. ROC analysis indicated that a 0.4 mV threshold for low voltage provided the best predictive performance. Logistic regression showed a 1.039-fold increase in recurrence risk per percent increase in LA low voltage area (odds ratio = 1.039, 95% CI 1.014-1.064). Low voltage extent in EAM correlates with 1-year recurrence rate after ablation of left atrial supraventricular arrhythmias. The threshold of 0.4 mV is the most suitable for predicting recurrences of those examined.

Efficacy and limitation of nonparoxysmal atrial fibrillation ablation in patients with heart failure with preserved ejection fraction.

Catheter ablation for atrial fibrillation (AF) reduces heart failure (HF) hospitalization in patients with HF with preserved ejection fraction (HFpEF). However, the long-term outcomes and subclinical HF after nonparoxysmal AF ablation in HFpEF patients have not been fully evaluated. One-hundred-ninety nonparoxysmal AF patients with left ventricular ejection fraction ≥50% who underwent first-time AF ablation were studied. HFpEF was diagnosed from a history of congestive HF and/or combined criteria of N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration and transthoracic echocardiogram parameters, including average septal-lateral E/e' and tricuspid regurgitation peak velocity. Ninety-five patients with HFpEF (HFpEF group) were compared with 95 patients without HF (CNT group). Low voltage area (LVA) was defined as an area with a bipolar electrogram of <0.5 mV covering >5% of the total left atrial surface. The primary endpoint was a composite of death from any cause or hospitalization for worsening HF. The secondary endpoint was subclinical HFpEF defined from NT-proBNP concentration and average septal-lateral E/e' or tricuspid regurgitation peak velocity at 6-12 months after the procedure irrespective of the rhythm. Kaplan-Meier curves showed that the primary composite endpoint did not differ between the two groups (mean follow-up period 707 ± 75 days, log-rank p = 0.5330). However, significantly more patients in the HFpEF group reached the secondary endpoint (42 [44%] vs. 13 [14%], p < 0.0001). Multivariate analysis revealed that a high preablation NT-proBNP (odds ratio [OR] 1.001, 95% confidence interval [CI] 1.001-1.002, p = 0.0040) and the existence of LVA (OR 5.983, 95% CI 1.463-31.768, p = 0.0194) independently predicted the secondary endpoint in HFpEF patients. After nonparoxysmal AF ablation, mortality of HFpEF patients was not inferior compared to patients without coexisting HF. However, subclinical HF occasionally persisted especially in HFpEF patients with a high preprocedure NT-proBNP concentration and LVA.

Clinical relevance of left atrial structural remodeling and non-pulmonary vein foci in atrial fibrillation.

The mechanistic role of left atrial (LA) structural remodeling as a non-pulmonary vein (PV) trigger in the initiation of atrial fibrillation (AF) remains uncertain. This study is aimed at prospectively evaluating the association between non-PV triggers and LA structural remodeling. A total of 517 patients undergoing catheter ablation for AF were included. After PV isolation, a standardized protocol was implemented to reveal non-PV triggers, which included burst pacing into AF followed by cardioversion during isoproterenol infusion. If pacing-induced atrial tachycardia (AT) was observed, mapping and catheter ablation were performed. The mean percentage of LA low-voltage area (LVA) < 0.5mV incrementally increased during right atrial pacing among the no induction (n = 470), AF (n = 21), and AT (n = 26) groups (2.6 ± 5.7%, 5.5 ± 6.4%, and 18.0 ± 21.5%, respectively; P < 0.001). In the AF induction group, non-PV foci originated from the left atrium in 13 of 25 foci (52%), and 8 of 13 LA non-PV foci (62%) were located in the septal region. All except 1 focus originated from the non-LVA < 0.5mV (8%), but 8 of the 13 LA foci originated from the LVA < 1.0mV (62%). There were no differences in AF recurrence among the groups (log-rank, P = 0.160). The majority of non-PV foci in the LA originated outside regions with advanced structural remodeling, thus suggesting the limited effectiveness of adjunctive ablation guided by the LVA < 0.5mV during sinus rhythm in eliminating non-PV triggers.

Dynamic Voltage Mapping of the Post-infarct Ventricular Tachycardia Substrate: A Practical Technique to Help Differentiate Scar from Borderzone Tissue.

During catheter ablation of post-infarct ventricular tachycardia (VT), substrate mapping is used when VT is non-inducible or poorly tolerated. Substrate mapping aims to identify regions of slowly conducting myocardium (borderzone) within and surrounding myocardial scar for ablation. Historically, these tissue types have been identified using bipolar voltage mapping, with areas of low bipolar voltage (<0.50 mV) defined as scar, and areas with voltages between 0.50 mV and 1.50 mV as borderzone. In the era of high-density mapping, studies have demonstrated slow conduction within areas of bipolar voltage <0.50 mV, suggesting that this historical cut-off is outdated. While electrophysiologists often adapt voltage cut-offs to account for this, the optimal scar-borderzone threshold is not known. In this review, we discuss dynamic voltage mapping, a novel substrate mapping technique we have developed, which superimposes data from both activation and voltage maps, to help delineate the post-infarct VT circuit through identification of the optimal scar-borderzone voltage threshold.

Ablation Strategies for Repeat Procedures in Atrial Fibrillation Recurrences Despite Durable Pulmonary Vein Isolation: The Prospective Randomized ASTRO AF Multicenter Trial.

Ablation strategies for patients with symptomatic atrial fibrillation and isolated pulmonary veins vary and their effects on arrhythmia recurrence remain unclear. A prospective randomized German multicenter trial sought to compare 2 ablation strategies in this patient cohort. Patients with atrial fibrillation despite durable pulmonary vein isolation were randomly assigned at 7 centers to undergo low-voltage area ablation using 3-dimensional mapping and irrigated radiofrequency current ablation (group A) or empirical left atrial appendage isolation (LAAI) using the cryoballoon followed by staged interventional left atrial appendage closure (group B). The primary end point was freedom from atrial tachyarrhythmias between 91 and 365 days after index ablation. The study was powered for superiority of LAAI compared with low-voltage area. Patients (40% women; mean age, 68.8±8 years) with paroxysmal (32%) or persistent atrial fibrillation (68%) were randomized to undergo low-voltage area ablation (n=79) or cryoballoon-guided LAAI (n=82). After a planned interim analysis, enrollment was halted for futility on January 10, 2023. In the LAAI group, 77 of 82 left atrial appendages were successfully isolated with subsequent left atrial appendage closure in 57 patients. Procedure-related complications occurred in 4 (5%) and 11 (13.5%) patients in group A and B, respectively (P=0.10). The median follow-up was 367 days (interquartile range, 359-378). The Kaplan-Meier point estimate for freedom from atrial tachyarrhythmias was 51.7% (CI, 40.9%-65.4%) for group A and 55.5% (CI, 44.4%-69.2%; P=0.8069) for group B. The current study did not detect superiority of cryoballoon-guided LAAI over low-voltage area ablation in patients with atrial fibrillation despite durable PVI. URL: https://www.clinicaltrials.gov; Unique identifier: NCT04056390.