Low-voltage Areas Research Articles

Regional left atrial conduction velocity in the anterior wall is associated with clinical recurrence of atrial fibrillation after catheter ablation: efficacy in combination with the ipsilateral low voltage area

BackgroundLeft atrial (LA) conduction velocity (CV) is an electrical remodeling parameter of atrial fibrillation (AF) substrate. However, the pathophysiological substrate of LA-CV and its impact on outcomes after catheter ablation for AF have not been well evaluated.MethodsWe retrospectively evaluated 119 patients with AF who underwent catheter ablation and electroanatomical mapping during sinus rhythm. To measure regional LA-CV, we took triplet sites (A, B, and C) on the activation map and calculated the magnitude of the matched orthogonal projection vector between vector-AB and vector-AC, indicating two-dimensional CV. The median of the LA-CVs from four triad sites in both the anterior and posterior walls was set as the ‘model LA-CV’. We evaluated the impact of the model LA-CV on recurrence after ablation and relationship between the model LA-CV and LA-low voltage area (LVA) of < 0.5 mV.ResultsDuring the 12-month follow-up, 29 patients experienced recurrence. The LA-CV model was significantly correlated with ipsilateral LVA. The lower anterior model LA-CV was significantly associated with recurrence, with the cut-off value of 0.80 m/s having a sensitivity of 72% and specificity of 67%. Multivariable analysis revealed that the anterior model LA-CV (hazard ratio, 0.09; 95% confidence interval, 0.01–0.94; p = 0.043) and anterior LA-LVA (hazard ratio, 1.06; 95% confidence interval, 1.00–1.11; p = 0.033) were independently associated with AF recurrence. The anterior LA-LVA was mildly correlated with the anterior model LA-CV (r = -0.358; p < 0.001), and patients with both lower LA-CV and greater anterior LA-LVA based on each cut-off value had the worst prognosis. However, decreased LA-CV was more likely to be affected by the distribution pattern of the LVA rather than the total size of the LVA.ConclusionDecreased anterior LA-CV was a significant predictor of AF recurrence and was a useful electrical parameter in addition to LA-LVA for estimating AF arrhythmogenicity.

Treatment of Patients after Pulmonary Vein Isolation in Persistent Atrial Fibrillation - Combined Use of a High-Density Map and Robotic Navigation

Objectives and Background: Atrial fibrillation (AF) is still associated with higher recurrence rate. This is prospective study of Redo pulmonary vein isolation (PVI) combined with remote magnet navigation. We have done high density mapping and in retrospective Analysis we tried to find criteria for better Ablation success. Materials and Methods: 50 patients (male 36, female 14) with indication for Redo-PVI ware included. A 20 polig multielectrode catheter was used for mapping. Mapping data were collected bevor and after ablation and processed in terms of low-voltage areas bipolar (3 groups: 0.05-0.15 mV, 0.15-0.25 mV, 0.25-0.5 mV) and change in unipolar amplitude at the ablation lesions. The primary endpoint (symptom freedom at 12 months) was evidenced by follow-up examinations at 3, 6,9,12 months. Non-parametric statistical methods were used for variables with non-normal distributions. Trends in success rates were evaluated using the Kaplan-Meier methodology and compared using a log-ranking test. Results: In all analysed low-voltage bipolar groups occurs a change in the distribution after ablation in patients with AF. There are 3 parameters which related with endpoint: area of bipolar signals 0.05-0.15 mV (Me +32%, [95% CI: -10% to +167%], p&lt;0.001), the unipolar amplitude at the applied ablation lesions (Me -0.45mV [95% CI: -0.15 to -1], p&lt;0,001) and unipolar amplitude at the attached ablation lesions (lower amplitude was with recurrence associated, p=0.004). According to ROC analysis and logistic regression: failure to meet all 3 criteria accompanied with a 67% probability of symptomatic recurrence, if all 3 criteria are met, it is expected to have an approximately 81% success rate within the 12 months. Conclusion: Analysis of a high-density map including 3 criteria, help us to improve ablation success.

Validating left atrial fractionation and low-voltage substrate during atrial fibrillation and sinus rhythm-A high-density mapping study in persistent atrial fibrillation.

Low-voltage-substrate (LVS)-guided ablation for persistent atrial fibrillation (AF) has been described either in sinus rhythm (SR) or AF. Prolonged fractionated potentials (PFPs) may represent arrhythmogenic slow conduction substrate and potentially co-localize with LVS. We assess the spatial correlation of PFP identified in AF (PFP-AF) to those mapped in SR (PFP-SR). We further report the relationship between LVS and PFPs when mapped in AF or SR. Thirty-eight patients with ablation naïve persistent AF underwent left atrial (LA) high-density mapping in AF and SR prior to catheter ablation. Areas presenting PFP-AF and PFP-SR were annotated during mapping on the LA geometry. Low-voltage areas (LVA) were quantified using a bipolar threshold of 0.5 mV during both AF and SR mapping. Concordance of fractionated potentials (CFP) (defined as the presence of PFPs in both rhythms within a radius of 6 mm) was quantified. Spatial distribution and correlation of PFP and CFP with LVA were assessed. The predictors for CFP were determined. PFPs displayed low voltages both during AF (median 0.30 mV (Q1-Q3: 0.20-0.50 mV) and SR (median 0.35 mV (Q1-Q3: 0.20-0.56 mV). The duration of PFP-SR was measured at 61 ms (Q1-Q3: 51-76 ms). During SR, most PFP-SRs (89.4 and 97.2%) were located within LVA (<0.5 mV and <1.0 mV, respectively). Areas presenting PFP occurred more frequently in AF than in SR (median: 9.5 vs. 8.0, p = 0.005). Both PFP-AF and PFP-SR were predominantly located at anterior LA (>40%), followed by posterior LA (>20%) and septal LA (>15%). The extent of LVA < 0.5 mV was more extensive in AF (median: 25.2% of LA surface, Q1-Q3:16.6-50.5%) than in SR (median: 12.3%, Q1-Q3: 4.7-29.4%, p = 0.001). CFP in both rhythms occurred in 80% of PFP-SR and 59% of PFP-AF (p = 0.008). Notably, CFP was positively correlated to the extent of LVA in SR (p = 0.004), but not with LVA in AF (p = 0.226). Additionally, the extent of LVA < 0.5 mV in SR was the only significant predictor for CFP, with an optimal threshold of 16% predicting high (>80%) fractionation concordance in AF and SR. Substrate mapping in SR vs. AF reveals smaller areas of low voltage and fewer sites with PFP. PFP-SR are located within low-voltage areas in SR. There is a high degree of spatial agreement (80%) between PFP-AF and PFP-SR in patients with moderate LVA in SR (>16% of LA surface). These findings should be considered when substrate-based ablation strategies are applied in patients with the left atrial low-voltage substrate with recurrent persistent AF.

Assessing the impact of blocking distal coronary sinus-left atrial muscular connection on inducible rate of atrial fibrillation and follow-up recurrence in persistent atrial fibrillation patients with different fibrotic degrees of left atrial: A retrospective study.

BackgroundThe musculature of the coronary sinus (CS), especially its distal connection with the post wall of the left atrial (LA), has been associated with the genesis and maintenance of atrial flutter (AFL) and atrial fibrillation (AF). However, the relative contributions of the distal coronary sinus (CSD)-LA connection to PersAF with various degrees of atrial fibrosis remain unknown.ObjectiveThis study aimed to explore the different roles of blocking the CSD-LA connection in the induction of acute AF and middle-term follow-up of recurrence among PersAF patients with various degrees of LA fibrosis.Methods and resultsA retrospective cohort of 71 patients with drug-refractory and symptomatic PersAF underwent ablation for the first time were studied. The population was divided into two groups according to disconnection of the CSD-LA or not. All patients enrolled accepted the unified ablation procedure (circumferential pulmonary vein isolation, non-pulmonary vein trigger ablation and ablation of the CSD-LA connection). Group A (n = 47) successfully blocked the CSD-LA electrical connection and Group B (n = 24) failed. Twenty-five patients could be induced into sustained AF in the Group A compared to 20 in the Group B (53.2 vs. 83.3%, p = 0.013). After a mean follow-up of 185 ± 8 days, 24 (33.8%) patients experienced atrial arrhythmia recurrences. The Group A had significantly fewer recurrences (25.5%) compared to Group B (50%). Meanwhile, in Group A, the ROC curve analysis suggested that in the case of blocking CSD-LA, low voltage area (LVA) of LA can act as a predictive factor for acute AF induction (AUC = 0.943, Cut-off = 0.190, P < 0.001) with sensitivity and specificity of 92.3 and 90.5%, and middle-term recurrence (AUC = 0.889, Cut-off = 0.196, P < 0.001) with sensitivity and specificity of 100 and 65.7%.ConclusionDisconnection of CSD-LA could reduce the inducible rate of acute AF and the recurrences of atrial arrhythmia during middle-term follow-up. The PersAF patients with CSD-LA muscular connection blocked, experienced a higher acute AF inducible rate with larger proportion of LVA of LA (≥19%) and a higher recurrent rate of atrial arrhythmias with a larger proportion of LA fibrosis (≥19.6%).

Detection of endo-epicardial atrial low-voltage areas using unipolar and omnipolar voltage mapping

Background: Low-voltage areas (LVA) can be located exclusively at either the endocardium or epicardium. This has only been demonstrated for bipolar voltages, but the value of unipolar and omnipolar voltages recorded from either the endocardium and epicardium in predicting LVAs at the opposite layer remains unknown. The goal of this study was therefore to compare simultaneously recorded endo-epicardial unipolar and omnipolar potentials and to determine whether their voltage characteristics are predictive for opposite LVAs. Methods: Intra-operative simultaneous endo-epicardial mapping (256 electrodes, interelectrode distances 2 mm) was performed during sinus rhythm at the right atrium in 93 patients (67 ± 9 years, 73 male). Cliques of four electrodes (2 × 2 mm) were used to define maximal omnipolar (Vomni,max) and unipolar (Vuni,max) voltages. LVAs were defined as Vomni,max ≤0.5 mV or Vuni,max ≤1.0 mV. Results: The majority of both unipolar and omnipolar LVAs were located at only the endocardium (74.2% and 82.0% respectively) or epicardium (52.7% and 47.6% respectively). Of the endocardial unipolar LVAs, 25.8% were also located at the opposite layer and 47.3% vice-versa. In omnipolar LVAs, 18.0% of the endocardial LVAs were also located at the epicardium and 52.4% vice-versa. The combination of epicardial Vuni,max and Vomni,max was most accurate in identifying dual-layer LVAs (50.4%). Conclusion: Unipolar and omnipolar LVAs are frequently located exclusively at either the endocardium or epicardium. Endo-epicardial LVAs are most accurately identified using combined epicardial unipolar and omnipolar voltages. Therefore, a combined endo-epicardial unipolar and omnipolar mapping approach is favoured as it may be more indicative of possible arrhythmogenic substrates.

Low voltage area as a predictor of recurrence after a single pulmonary vein isolation procedure: results of the WAVE-MAP AF study

Abstract Background/Introduction Pulmonary vein isolation (PVI) is a recommended approach for atrial fibrillation (AF) ablation procedures. Substrate modification beyond PVI has mixed results but identifying and ablating low voltage zones and ablating those targets in addition to PVI may be beneficial. Electroanatomic mapping is critical to identify subjects that may require further substrate modification. Low voltage area may be predictive of optimal treatment approach. Purpose This was a prospective, multicenter, interventional study of a high-density grid-style mapping catheter (HD Grid) to characterize left atrial low voltage substrate during sinus rhythm (SR) and AF and identify associations with 12 month recurrence rates after a single de novo radiofrequency (RF) ablation using a PVI only approach. Methods This study (NCT03882021) enrolled 300 subjects at 18 centers in Europe and Israel. Subjects underwent de novo RF ablation for paroxysmal AF (PAF) (N=113), early persistent AF (PsAF; AF sustained 7 days to 3 months) (N=86) or non-early PsAF (AF sustained &amp;gt;3 months to 12 months) (N=101). High density voltage maps were collected with HD Grid. Two pre-ablation maps, in SR and AF, were created for each subject (N=196) followed by PVI only ablation. Low voltage area (using cutoffs of 0.1 mV to 1.5 mV) was investigated in SR and AF. Follow up visits were at 3, 6 and 12 months post-ablation, with a 24-hour Holter monitor at 12 months. A Cox proportional hazards model was used to identify associations between mapping data and 12 month AF/atrial flutter (AFL)/atrial tachycardia (AT) recurrence after a single PVI procedure. Results At 12 months, 75.5% of subjects were free from AF/AFL/AT recurrence. On average, PsAF subjects had more low voltage area than PAF subjects in SR and AF. However, while univariate analysis found no correlation between recurrence and PAF or PsAF diagnosis (p=0.1261), those with recurrence had a significantly larger percent left atrial low voltage area under 0.5 mV with simultaneous orthogonal bipole wave configuration (HDW) in both AF (p=0.0011) and SR (p=0.0210) than those without recurrence. Using HDW, low voltage area (identified as &amp;lt;0.5 mV) greater than 28% of the left atrium in SR (HR: 4.82, 95% CI: 2.08–11.18, p=0.0003) and greater than 72% in AF (HR: 5.66, 95% CI: 2.34–13.69, p=0.0001) were associated with a higher risk of AF/AFL/AT recurrence at one year. Conclusion(s) Using a standard cutoff of 0.5 mV, a larger percent low voltage area was associated with increased risk of recurrence in both SR and AF. Future analyses will explore optimal low voltage cutoffs and thresholds predictive of recurrence that may necessitate additional substrate modification beyond PVI. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): Abbott

Diagnostic value of electroanatomical mapping in patients with suspected arrhythmogenic cardiomyopathy

Abstract Background Case series suggested that low voltage areas (LVA) on invasive electroanatomical mapping (EAM) could identify arrhythmogenic cardiomyopathy (ACM) at an earlier stage as compared to late gadolinium enhancement (LGE) and fatty infiltration on cardiac magnetic resonance (CMR). Data comparing LVA with structural abnormalities on CMR are lacking. Purpose To report the prevalence of substrate abnormalities identified by EAM vs. CMR in a cohort of patients with suspected ACM. Methods We retrospectively identified 66 consecutive patients with suspected ACM, who underwent EAM following clinical onset with ventricular arrhythmias. The cutoff value for EAM-defined LVA was &amp;lt;0.5 mV bipolar, &amp;lt;8 mV unipolar. Data from a prior CMR, performed no more than 12 months before, were used for comparison. Results The study cohort (mean age 47 years, range 21–76; 83% males; mean left ventricular ejection fraction 53%, range 28–70%) was composed of patients with suspected ACM involving either the right (n=62) or the left ventricle (n=4) following presentation with sustained monomorphic ventricular tachycardia. EAM was obtained by isolated endocardial, epicardial, or combined approach, respectively, in 11 (17%), 15 (23%) and 40 (61%) patients. Overall, 61 patients (92%) had documented LVA, of whom 89% showed an epicardial localization. In the same population, CMR identified a lower prevalence of substrate abnormalities (LGE 65%; fatty infiltration 50%). In particular, there were 27 patients (41%) with EAM-defined LVA and absent substrate abnormalities on CMR. Based on the 2010 Task Force Criteria and the 2021 Padua Criteria, a definite diagnosis of ACM was missing for a total of 19 patients (29%): due to the uniform identification of LVA in the absence of CMR abnormalities, EAM helped to establish the most likely diagnosis of ACM in all of them (19/19). Conclusions Our data suggest that EAM is capable of identifying substrate abnormalities in a consistent proportion of patients with suspected ACM and absent abnormalities on CMR. In this setting, the implementation of LVA to the current diagnostic criteria could improve the diagnostic yield for ACM. Funding Acknowledgement Type of funding sources: None.

The left atrial low-voltage area and persistent atrial fibrillation treated with pulmonary vein isolation alone

Abstract Background There are limited data regarding the association between the burden of the left atrial low-voltage area (LVA) and the outcome of pulmonary vein isolation (PVI) alone in persistent atrial fibrillation (PeAF). Purpose The study aimed to investigate the impact of the burden of LVA on the patients with PeAF treated with PVI alone. Methods Using a retrospective cohort of PeAF patients who underwent PVI alone, both clinical and the left atrial voltage mapping data were reviewed. LVA was defined as an area of ≤0.5 mV (bipolar) when mapped during sinus rhythm and ≤0.2 mV during AF. The high burden of LVA was defined as a case when the LVA constitutes ≥10% of the total left atrial body area. The patients were categorized into either the high or low burden groups. The recurrence of any atrial tachyarrhythmia was followed up, and multivariable Cox's regression analysis was performed. Results A total of 50 and 25 patients were investigated for the low burden (LVA&amp;lt;10%) and high burden (LVA≥10%) groups, respectively. Compared to the low burden group, the high burden group had a significantly less male proportion (56.0% versus 78.0%), a higher CHA2DS2-VASc score (median 3 versus 2), more chronic kidney disease (16.0% versus 2.0%), and a higher burden of LVA (20±11% versus 5±3%). During the median follow-up of 9.5 (6.2–16.2)months, there were 30.0% and 48.0% ofrecurrences for the low and high burden groups, respectively. Compared to the low burden group, the high burden group was associated with higher risks of both early and late recurrences (HR [95% CI] =2.67 [1.15–6.18] and 2.08 [1.03–4.20], respectively) (Figure 1). The best cut-off of LVA to predict 2-year recurrence was 10.1% (Figure 2). Conclusion The high burden of LVA was significantly associated with an increased risk of recurrence among PeAF patients treated with PVI alone. Tailored ablation in addition to PVI would be needed to improve outcomes in patients with PeAF having a high burden of LVA. Funding Acknowledgement Type of funding sources: None.

Baseline profile and results of atrial fibrillation ablation in patients with arrhythmia-induced cardiomyopathy

Abstract Background Atrial fibrillation (AF) is known to trigger a reversible dilated cardiomyopathy referred as arrhythmia-induced CM (AiCM). However, it remains unclear why some patients are more prone to develop AiCM than others and there is scarce information about their clinical outcomes after AF ablation. Purpose We ought to find clinical and analytical predictors for the development of AiCM and recovery of LVEF in patients referred for AF ablation. Methods A prospective multicenter study of consecutive patients undergoing point-by-point radiofrequency (RF) catheter ablation between September 2016 and November 2021 was conducted. The low voltage areas and left atrial (LA) volume were analyzed offline on high density electroanatomical maps collected prior to RF ablation. Peripheral blood sample for biomarker analysis (Gal-3, FABP4 and sRAGE) were obtained at the time of the procedure. Results 803 consecutive patients were included, median age was 61 and 240 (30,81%) were women. AF pattern was paroxysmal in 254 (32,60%) and persistent in 534 (68,55%; of whom, long-standing persistent in 113 (14,51%) patients). The median follow-up period was 23.83 months [IQR 9 to 36]. The multivariate analysis revealed LA area, width of QRS segment, persistent AF and chronic kidney disease (CKD) as independent predictors for AiCM. Recurrence-free survival was not different amog both cohorts (Figure 1). The median increase in LVEF from baseline to the 6-month follow-up visit in patients with AiCM was 16% (CI 14.31–18.47) without changes in the non-AiCM group. The median LVEF previously to CA from patients in the AiCM group was 38% (IQR 30–45%) and after the procedure 57% (IQR 50–60%) [see figure 2]. Conclusions AiCM is characterized to have a particularly complex pathophysiology not fully understood thus far. Pulmonary vein isolation in patients is safe and suitable for patients that suffered from tachycardiomyopathy. We found that persistent AF and chronic kidney disease play a key role in its development. Neither peripheral blood biomarkers nor left atrial samples showed relevant association with its occurrence. Funding Acknowledgement Type of funding sources: None.

Electrophysiological insights into left atrial conduction times and regional velocities in atrial fibrillation patients with and without fibrotic atrial cardiomyopathy

Abstract Background Although considerable progress has been made in understanding the process of arrhythmogenesis in atrial fibrillation (AF) patients and the role of atrial substrate, little is known about atrial conduction characteristics in different grades of fibrotic atrial cardiomyopathy (FACM) and specific left atrial (LA) regions. Purpose The aim of this study was to evaluate left atrial conduction times (LACT) and -velocities (CV) in electroanatomical high density maps during sinus rhythm in AF patients with and without signs of atrial fibrosis. Methods Before radiofrequency catheter ablation electroanatomical high density mapping was performed in 41 AF patients (n=38 persistent, n=3 paroxysmal) using a 10-polar circular mapping catheter and the CARTO3 V7 navigation system (Biosense Webster, Diamond Bar, CA). We evaluated the size of low voltage areas (LVA ≤0.5mV), LACTs and local CVs at the anterior and posterior wall in low voltage areas and normal voltage areas (NVA ≥1.5mV). The latter were specifically calculated in the direction of wave-front propagation (coherent algorithm) by using 3-dimensional coordinates and local activation times of triads of sites. Results 20 FACM and 21 non-FACM maps were analysed (1823±1031 points, n=16 low grade FACM I+II, n=4 high grade FACM III+IV, EF 57.24±6,18%, LAVI 43.01±15,63 ml/m2). The mean total size of LVA in FACM patients was 12.06 cm2 (anterior wall 9.51 cm2, posterior wall 2.55 cm2). LACT was 109.15±25.30 ms in our AF population, whereby LACT was shown to be longer (118.79ms, +18%) in FACM patients compared to patients without substrate (100.40 ms, p=0.01), particularly pronounced in high grade FACM (III–IV) (146 ms, +46%, p=0.001). The extension of LVA fairly strong correlated with LACT duration (Spearman ρ= 0.76). Conduction velocities in LVA revealed significantly lower (−55%) than those in NVA (0.61±0.11m/s vs. 1.34±0.30m/s, p=0.000). When comparing the anterior to the posterior wall, anterior conduction appeared slower than posterior conduction, which was significant in NVA (−12%, 1.02 vs. 1.16 m/s, p=0.0053) and failed to reach statistical significance in LVA (−11.6%, 0.61 vs. 0.069 m/s, p=0.39). See Figure 1 and Table 1 for more clinical and electrophysiological characteristics in FACM vs. non FACM patients. Conclusion Total LACT is significantly prolonged in FACM patients and seems to correlate with LVA size. Compared to areas with a normal bipolar voltage (≥1.5mV) LVAs (≤0.5mV) show a 55% CV reduction. Furthermore, regional CVs were shown to differ between the anterior and the posterior LA wall. Those findings might have an impact on developing substrate-based ablation strategies in catheter ablation of FACM patients. Funding Acknowledgement Type of funding sources: None.

Correlations between endocardial voltage mapping, diagnosis and genetic in patients with arrhythmogenic right ventricular cardiomyopathy

Abstract Background The relations between voltage mapping and diagnosis or genetic background of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) have not been investigated so far. Objective To investigate if diagnosis or genetic background were linked to voltage mapping in ARVC. Method 97 patients with proved or suspected ARVC undergoing 3D endocardial mapping and genetic testing have been retrospectively included. Presence, localisation and extension of low voltage areas were correlated to ARVC diagnosis and presence of a culprit mutation. Results 68 patients (70%) fulfilled ARVC diagnosis according to the Task Force criteria and 43 (44%) had ARVC-causal mutations. 78 (80%) presented with some bipolar or unipolar endocardial scar. 60/ 78 patients with endocardial scar (77%) fulfilled the criteria for a definitive ARVC diagnosis versus 8/19 patients without scar (42%) (p=0.003). In the 68 patients with a definitive diagnosis of ARVC, the presence of endocardial scar was similar whether an ARVC-causal mutation was present or not (35/40 vs 25/28, p=ns). While there was slightly more infero-lateral scars in patients carrying a pathogenic genetic variant (34/40 vs 18/28, p=0.04), there was no difference for right ventricular outflow tract (24/40 vs 17/28) and apical scars (12/40 vs 11/28) or for multiple scars (26/35 vs 14/25 patients with scars). Scar extension was greater in patients with pathogenic variants (bipolar 12±10 vs 6±10%, p=0.02, and unipolar 22±13 vs 12±15%, p=0.01). Conclusion 3D endocardial mapping could have an important role for refining ARVC diagnosis. Trends for larger and more infero-lateral scars were observed in mutated patients, without difference according to the mutated genes. Funding Acknowledgement Type of funding sources: None.

Electroanatomic mapping and radiofrequency catheter ablation of atrial fibrillation or atrial tachycardia in patients with pulmonary hypertension. Ancillary analysis

Abstract Background Atrial fibrillation (AF) and related atrial tachycardias (ATs) are common arrhythmias in patients with pulmonary hypertension (PH). They are currently assessed in a multicentre randomized trial investigating extensive radiofrequency catheter ablation of the arrhythmogenic substrate on top of selective ablation of clinical arrhythmia alone. Purpose Irrespective of the randomization scheme, we compared clinical and procedural characteristics in patients with AF versus those with right-sided ATs. Methods Out of 74 patients with combined post- and pre-capillary or isolated pre-capillary PH, two study subgroups were composed: AF group included 40 patients and AT group included 31 patients: 24 with typical atrial flutter (AFL) and 7 with other right-sided ATs (2 upper loop reentry ATs, 2 focal ATs from coronary sinus ostium, 1 focal AT from terminal crest, and 2 polymorphic ATs from high right atrium). Three patients with inducible AV nodal reentrant tachycardia were excluded from this analysis. Biatrial electroanatomic mapping was performed in all patients. The data are presented as medians (interquartile range) and compared by the Mann-Whitney U test. Results The clinical and procedural characteristics of AF and AT groups are shown in Table. Cycle length (CL) of both induced and spontaneous AFL was 302 (267; 324) ms. Non-CTI-dependent ATs had CL 425 (350; 480) ms. In patients with AF, the dominant CL was 183 (152; 221) and 191 (154; 210) ms in right and left atrial appendage, respectively. In the whole cohort, pulmonary vein isolation was done in 49 (66%), left atrial substrate ablated in 23 (31%), cavotricuspid isthmus block achieved in 46 (62%), superior vena cava isolation completed in 28 (39%), intercaval line ablated in 26 (36%), and right atrial substrate or focal activity ablated in 8 (11%) cases. The procedure was technically successful in 72 (97%) patients. Conclusion Patients with right-sided ATs had expectedly more dilated right atrium. This was not, however, associated with a higher prevalence of right atrial low-voltage areas. Left atrial electroanatomic remodelling in AF patients was concordant with that frequently observed in non-PH patients with AF. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of Health of the Czech Republic.

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

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

Automatic identification method of topology structure of low-voltage distribution station area based on multi-point measurement data

In order to improve the accuracy and success rate of the identification results of the topology structure of the station area, an automatic identification method of the topology structure of the low-voltage distribution station area based on multi-point measurement data is proposed. LoRa technology is used to obtain multi-point measurement data, and with the help of protocol compression technology, the acquisition of massive high-density measurement data is completed. A current-based identification model for the affiliation of equipment in the station area is constructed, and the affiliation between the primary branch and the secondary branch, and the affiliation between the secondary branch and the user energy meter cluster set are obtained by using the model. Finally, the DTW distance and cluster analysis are used to analyze the distribution terminal and the collected measurement data. So as to realize the automatic identification of the topology structure of the low-voltage distribution station area. The experimental results show that the identification results of the proposed method are more accurate, and the success rate is also effectively improved.

Correlation between Cardiac MRI and Voltage Mapping in Evaluating Atrial Fibrosis: A Systematic Review.

To provide an overview of existing literature on the association between late gadolinium enhancement (LGE) cardiac MRI and low voltage areas (LVA) obtained with electroanatomic mapping (EAM) or histopathology when assessing atrial fibrosis. A systematic literature search was conducted in the PubMed, Embase, and Cochrane Library databases to identify all studies published until June 7, 2022, comparing LGE cardiac MRI to LVA EAM and/or histopathology for evaluation of atrial fibrosis. The study protocol was registered at PROSPERO (registration no. CRD42022338243). Two reviewers independently evaluated the studies for inclusion. Risk of bias and applicability for each included study were assessed using Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) criteria. Data regarding demographics, electrophysiology, LGE cardiac MRI, and study outcomes were extracted. The search yielded 1048 total results, of which 22 studies were included. Nineteen of the 22 included studies reported a significant correlation between high signal intensity at LGE cardiac MRI and LVA EAM or histopathology. However, there was great heterogeneity between included studies regarding study design, patient samples, cardiac MRI performance and postprocessing, and EAM performance. Current literature suggests a correlation between LGE cardiac MRI and LVA EAM or histopathology when evaluating atrial fibrosis but high heterogeneity between studies, demonstrating the need for uniform choices regarding cardiac MRI and EAM acquisition in future studies.Keywords: Cardiac, MR Imaging, Left Atrium Supplemental material is available for this article. © RSNA, 2022.

Integration of 3D nuclear imaging in 3D mapping system for ventricular tachycardia ablation in patients with implanted devices: Perfusion/voltage retrospective assessment of scar location.

The identification of low-voltage proarrhythmic areas for catheter ablation of scar-mediated ventricular tachycardia (VT) remains challenging. Integration of myocardial perfusion imaging (single-photon emission computed tomography/computed tomography; SPECT/CT) and electroanatomical mapping (EAM) may improve delineation of the arrhythmogenic substrate. To assess the feasibility of SPECT/CT image integration with voltage maps using the EnSite Precision system (Abbott) in patients undergoing scar-mediated VT ablation. Patients underwent SPECT/CT imaging prior to left ventricular (LV) EAM with the EnSite Precision mapping system. The SPECT/CT, EAM data, and ablation lesions were retrospectively co-registered in the EnSite Precision system and exported for analysis. Segmental tissue viability scores were calculated based on SPECT/CT perfusion and electrogram bipolar voltage amplitude. Concordance, specificity, and sensitivity between the 2 modalities as well as the impact of SPECT/CT spatial resolution were evaluated. Twenty subjects (95% male, 67 ± 7 years old, left ventricular ejection fraction 36% ± 11%) underwent EAM and SPECT/CT integration. A concordance of 70% was found between EAM and SPECT/CT for identification of cardiac segments as scar vs viable, with EAM showing a 68.5% sensitivity and 76.4% specificity when using SPECT/CT as a gold standard. Projection on low-resolution 3D geometries led to an average decrease of 38% ± 22% of the voltage points used. The study demonstrated the feasibility of integrating SPECT/CT with EAM performed retrospectively for characterization of anatomical substrates during VT ablation procedures.

Evaluation of Isolation Area, Myocardial Injury and Left Atrial Function Following High-Power Short-Duration Radiofrequency or Second-Generation Cryoballoon Ablation for Atrial Fibrillation.

This randomized study aims to compare the left atrial (LA) lesion size, function, and tissue damage following pulmonary vein isolation (PVI) by high-power short-duration (HPSD) radiofrequency (RF) and second-generation cryoballoon (CB2) ablation. We enrolled 40 patients with paroxysmal atrial fibrillation who underwent PVI by HPSD RF (n = 21) or CB2 (n = 19). Every patient underwent LA CT angiography and transthoracic echocardiography (TTE) to assess the LA anatomy and function. Biomarker levels (hs-cTnT, hs-CRP, LDH) were compared pre- and post-procedurally. Pre- and post-ablation high-density mapping (HDM) was performed. The isolation area was defined under 0.2 mV bipolar voltage (low voltage area, LVA). We calculated the post-PVI LVA/LA surface ratio using LA CT-HDM merge images. At 3-month follow-up, TTE was performed to assess the changes in LA function. Post-ablation hs-cTnT level was significantly higher in the RF group (RF: 1249 ± 469 ng/L, CB2: 995 ± 280 ng/L, p = 0.024). Post-PVI hs-CRP (RF: 9.53 ± 10.30 mg/L, CB2: 12.36 ± 5.76 mg/L, p = 0.034) and LDH levels (RF: 349.9 ± 65.6 U/L, CB2: 451.6 ± 91.3 U/L, p < 0.001) were significantly higher following CB2 ablation. Post-PVI LVA/LA surface ratios were 8.37 ± 6.42% in the RF group and 13.58 ± 8.92% in the CB2 group (p = 0.022). LA function did not change significantly after the PVI procedure. Our data indicate that second-generation cryoballoon ablation produces a significantly larger LA lesion size compared to “point-by-point” HPSD radiofrequency. Both techniques preserve LA function. The myocardial component of tissue loss appears to be higher using HPSD radiofrequency ablation, with less collateral damage.

The Role of Fatty Acid-Binding Protein 4 in the Characterization of Atrial Fibrillation and the Prediction of Outcomes after Catheter Ablation.

Aims: The utility of biomarkers in characterizing atrial cardiomyopathy is unclear. We aim to test the ability of biomarkers of fibrosis (galectin-3 (Gal-3)) and adiposity (fatty acid-binding protein 4 (FABP4) and leptin) to predict: (1) the presence of low-voltage areas (LVA) in the electroanatomic voltage mapping; and (2) the recurrence of atrial fibrillation (AF) after pulmonary vein isolation (PVI). Methods: Patients referred for PVI were enrolled. Areas of bipolar voltage < 0.5 mV were considered as LVA. An aggregate score incorporating AF pattern (paroxysmal, persistent and long-standing persistent) and peripheral levels of FABP4 (>20 ng/mL) was developed. Results: 299 patients were included. AF was paroxysmal in 100 (33%), persistent in 130 (43%) and long-standing persistent in 69 (23%). Multivariable analysis revealed age, left atrium area, and the proposed score as independent predictors of LVA. During a mean follow-up period of 972 ± 451 days, freedom from AF recurrence was 63%. The score incorporating AF pattern and FABP4 levels accurately predicted freedom from AF recurrence, stratifying risk into ranges from 28% (score of 1) to 68% (score of 3). Cox regression models identified the score including AF pattern + FABP4 as the best model for AF recurrence (hazard ratio 2.32; 95% CI, 1.19 to 4.5; p = 0.014). Conclusions: Traditional clinical classification of atrial cardiomyopathy may be improved by markers of adiposity (FABP4). The combination allows better prediction of the presence of LVA and AF recurrence post-PVI. Gal-3 provided no added predictive value.

Algorithm for determining the fibrosis stage using high-density mapping

Aims. To develop an algorithm for assessing the stage of fibrosis based on high-density endocardial mapping. To study the effect of the stage of left atrial (LA) fibrosis on the results of atrial fibrillation (AF) catheter ablation.Methods. The study included 64 patients with paroxysmal or persistent AF, who underwent high-density LA mapping and catheter ablation. After the intervention procedure, we analyzed the electroanatomical maps of the left atrium, assessed the prevalence of low-voltage areas according to the developed algorithm. Patients were divided into 4 groups depending on the prevalence of areas of low voltage based on the Utah score.Results. The follow-up period was 14.5 ± 6.7 months. AF recurrence developed in 18 (28.1%) patients after the ablation procedure. AF recurrence after ablation was more frequent in patients with a low-voltage area of more than 20% than in patients with a low-voltage left atrial area of less than 20%, 6 (15.4%) versus 12 (48%), p=0.02. A logistic regression analysis was performed to identify AF recurrence predictors in the postoperative period. As a result, only widespread areas of low-amplitude activity were an independent predictor of AF recurrence after the pulmonary veins isolation, this predictive model was significant (p=0.026). Significant statistical differences between groups I, II and III,I V are the ejection fractions and the duration of the P-wave. Patients with low-voltage regions have lower left ventricular ejection fraction (62.8±6.9% versus 58.1±5.7%, p=0.01), and longer P-wave duration (84.7±8,2 ms versus 101.5±11.0 ms, p=0.01).Conclusion. LA high-density mapping before AF ablation makes it possible to determine the prevalence of low-voltage areas. After regression analysis, it was proved that common low-voltage areas are an independent predictor of AF recurrence after pulmonary vein isolation. Patients with low-voltage areas of more than 20% of the LA surface have longer P-wave duration and lower left ventricular ejection fraction.

Efficacy and safety of low voltage area ablation for atrial fibrillation: a systematic review and meta-analysis.

Pulmonary vein isolation is the cornerstone of atrial fibrillation (AF) ablation. However, the recurrence rate of AF after pulmonary vein isolation (PVI) remains high. The efficacy and safety of low voltage area (LVA) ablation in the treatment of AF are uncertain. The studies comparing the efficacy and safety of LVA ablation and LVA non-ablation for AF were systematically reviewed and meta-analyzed. Outcomes of interest included recurrent event, procedure time, and fluoroscopy time. Continuous variables were evaluated with mean deviation (MD) and standard mean difference (SMD). Odds ratio (OR) values and its 95% confidence intervals (CI) were used in meta-analysis of binary variables. Fourteen studies were eligible for inclusion. The AF recurrence was similar between the two groups, with no statistical difference (25.7% (67/346) vs. 28% (63/225), P = 0.49). LVA ablation did not increase the incidence of AT (8.7% (20/231) vs. 14.5% (28/193), P = 0.66). Fluoroscopy time was longer in the LVA ablation group (31.4 ± 8.4min vs. 26.3 ± 7.8min, P < 0.05). Complication rates were similar between the two groups (26.6% (17/64) vs. 21.7% (13/60), P = 0.53). Patients with LVA had higher AT/AF recurrence (32.9% (213/647) vs. 24.2% (229/948), P < 0.05). Patients with left atrial LVA have a poor prognosis after catheter ablation. LVA ablation did not reduce the recurrence of AF nor did it increase the recurrence of atrial tachycardia.