Comparison of Unipolar and Bipolar Voltage Mapping for Localization of Left Atrial Arrhythmogenic Substrate in Patients With Atrial Fibrillation

Background: Presence of left atrial low voltage substrate in bipolar voltage mapping is associated with increased arrhythmia recurrences following pulmonary vein isolation for atrial fibrillation (AF). Besides local myocardial fibrosis, bipolar voltage amplitudes may be influenced by inter-electrode spacing and bipole-to-wavefront-angle. It is unclear to what extent these impact low voltage areas (LVA) in the clinical setting. Alternatively, unipolar electrogram voltage is not affected by these factors but requires advanced filtering.Objectives: To assess the relationship between bipolar and unipolar voltage mapping in sinus rhythm (SR) and AF and identify if the electrogram recording mode affects the quantification and localization of LVA.Methods: Patients (n = 28, 66±7 years, 46% male, 82% persistent AF, 32% redo-procedures) underwent high-density (>1,200 sites, 20 ± 10 sites/cm2, using a 20-pole 2-6-2 mm-spaced Lasso) voltage mapping in SR and AF. Bipolar LVA were defined using four different thresholds described in literature: <0.5 and <1 mV in SR, <0.35 and <0.5 mV in AF. The optimal unipolar voltage threshold resulting in the highest agreement in both unipolar and bipolar mapping modes was determined. The impact of the inter-electrode distance (2 vs. 6 mm) on the correlation was assessed. Regional analysis was performed using an 11-segment left atrial model.Results: Patients had relevant bipolar LVA (23 ± 23 cm2 at <0.5 mV in SR and 42 ± 26 cm2 at <0.5 mV in AF). 90 ± 5% (in SR) and 85 ± 5% (AF) of mapped sites were concordantly classified as high or low voltage in both mapping modes. Discordant mapping sites located to the border zone of LVA. Bipolar voltage mapping using 2 vs. 6 mm inter-electrode distances increased the portion of matched mapping points by 4%. The unipolar thresholds (y) which resulted in a high spatial concordance can be calculated from the bipolar threshold (x) using following linear equations: y = 1.06x + 0.26mV (r = 0.994) for SR and y = 1.22x + 0.12mV (r = 0.998) for AF.Conclusion: Bipolar and unipolar voltage maps are highly correlated, in SR and AF. While bipole orientation and inter-electrode spacing are theoretical confounders, their impact is unlikely to be of clinical importance for localization of LVA, when mapping is performed at high density with a 20-polar Lasso catheter.

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P605Correlation of left atrial phasic transport function and arrhythmogenic substrate in patients with atrial fibrillation: cardiac magnetic resonance feature tracking and bipolar voltage mapping

European Heart Journal ◽

10.1093/eurheartj/ehz747.0214 ◽

2019 ◽

Vol 40 (Supplement_1) ◽

Author(s):

R Schoenbauer ◽

J Tomala ◽

B Kirstein ◽

Y Huo ◽

T Gaspar ◽

...

Keyword(s):

Atrial Fibrillation ◽

Cardiac Magnetic Resonance ◽

Magnetic Resonance ◽

Left Atrial ◽

Strain Rates ◽

Transport Function ◽

Bipolar Voltage ◽

Voltage Mapping ◽

Arrhythmogenic Substrate ◽

Booster Pump

Abstract Background Bipolar voltage mapping is a widely accepted approach to identify areas of arrhythmogenic substrate in patients presenting for atrial fibrillation (AF) ablation. However, until now little is known about the correlation of left atrial (LA) bipolar voltage distribution and LA transport function. Purpose To study the impact of LA low voltage zones (LVZ) on LA transport function. Methods 107 consecutive patients presenting for ablation of symptomatic AF (34 paroxysmal AF, 73 persistent AF) were prospectively enrolled. Each patient underwent cardiac magnetic resonance imaging (CMR) within 24 hours prior to the ablation procedure. 59 patients were in sinus rhythm (SR) and 48 in AF. LA phasic indexed volumes (LAVi) and ejection fractions were calculated using biplane area length formula. In addition LA phasic strains and strain rates were analyzed using dedicated software (Figure 1A & B). LA bipolar voltage mapping was performed prior to beginning of ablation in sinus rhythm using a 3-dimensional mapping system and LVZ were defined as areas of bipolar voltage <0.5mV. Results LVZ were present in 47 patients (23 in SR). The area of LVZ was 14.6cm2 (5.3–34.0). For patients in AF at the time of CMR only elevated minimal and maximal LAVi (p=0.001 and p=0.002 respectively) but no LA functional parameter was predictive for the occurrence of LVZ. In contrast for patients in SR all LA phasic volumes (endsystolic, pre atrial contraction and enddiastolic LAVi) and LA function parameters (passive, active and total ejection fraction (EF), reservoir, conduit and booster pump strains and strain rates) were predictive for the occurrence of LVZ. After clustered and pooled multivariate logistic regression only impaired booster pump strain rate was still predictive for occurrence of LVZ (OR 0.974, 95% CI 0.950–0.998, p=0.036). In addition Pearson correlation analysis revealed a strong link between LA booster pump functional parameters and cm2 expansion of LVZ areas: LA active EF, LA booster pump strain and SR (r=−0.42, p=0.044; r=−0.47, p=0.024; r=−0.65, p=0.001 [Figure 1C] respectively). Conclusion For patients in SR LA transport function is closely linked to the occurrence of LA LVZ and outperforms LA volumetric measurements for the prediction of LA LVZ. Furthermore LA booster pump function parameters show robust correlation to the extension of LA LVZ.

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10 Automated high density left atrial voltage mapping of low voltage areas in atrial fibrillation differs from sinus rhythm

10.1136/heartjnl-2021-ics.10 ◽

2021 ◽

Author(s):

J Mannion ◽

SJ Lennon ◽

J Keaney ◽

J Galvin ◽

J O’Brien ◽

...

Keyword(s):

Atrial Fibrillation ◽

Sinus Rhythm ◽

Left Atrial ◽

Low Voltage ◽

High Density ◽

Voltage Mapping

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Relationship between left atrial strain and left atrial bipolar voltage in patients undergoing catheter ablation for atrial fibrillation

European Heart Journal ◽

10.1093/ehjci/ehaa946.0387 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

Y Takahashi ◽

T Kitai ◽

T Watanabe ◽

T Fujita

Keyword(s):

Atrial Fibrillation ◽

Left Atrial ◽

Speckle Tracking ◽

Longitudinal Strain ◽

Low Voltage ◽

Pulmonary Veins ◽

Global Longitudinal Strain ◽

Inferior Wall ◽

Bipolar Voltage ◽

Global Mean

Abstract Background Low-voltage zone (LVZ) in the left atrium (LA) seems to represent fibrosis. LA longitudinal strain assessed by speckle tracking method is known to correlate with the extent of fibrosis in patients with mitral valve disease. Purpose We sought to identify the relationship between LA longitudinal strain and LA bipolar voltage in patients with atrial fibrillation (AF). We tested the hypothesis that LA strain can predict LA bipolar voltage. Methods A total of 96 consecutive patients undergoing initial AF ablation were analyzed. All patients underwent transthoracic echocardiography including 2D speckle tracking measurement on the day before ablation during sinus rhythm (SR group, N=54) or during AF (AF group, N=42). LA longitudinal strain was measured at basal, mid, and roof level of septal, lateral, anterior, and inferior wall in apical 4- and 2-chamber view. Global longitudinal strain (GLS) was defined as an average value of the 12 segments. LA voltage map was created using EnSite system, and global mean voltage was defined as a mean of bipolar voltage of the whole LA excluding pulmonary veins and left atrial appendage. LVZ was defined as less than 1.0 mV. Results There was a significantly positive correlation between GLS and global mean voltage (r=0.708, p<0.001). Multivariate regression analysis showed that GLS and age were independent predictors of global mean voltage. There was a significant negative correlation between global mean voltage and LVZ areas. Conclusions There was a strong correlation between LA longitudinal strain and LA mean voltage. GLS can independently predict LA mean voltage, subsequently LVZ areas in patients with AF. Funding Acknowledgement Type of funding source: None

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Atrial tissue characterization by cardiac magnetic resonance and high-density mapping in patients with atrial fibrillation

EP Europace ◽

10.1093/europace/euab116.137 ◽

2021 ◽

Vol 23 (Supplement_3) ◽

Author(s):

R Adelino Recasens ◽

L Llorca-Fenes ◽

A Sarrias ◽

A Teis ◽

V Bazan ◽

...

Keyword(s):

Left Atrial ◽

Tissue Characterization ◽

High Density ◽

Atrial Fibrosis ◽

Kappa Index ◽

Bipolar Voltage ◽

Voltage Mapping ◽

Point Correlation ◽

Left Atrial Fibrosis ◽

Lge Cmr

Abstract Funding Acknowledgements Type of funding sources: None. BACKGROUND Left atrial fibrosis is a marker of atrial disease and it has an important role in the pathophysiology of atrial fibrillation (AF). Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) is an emerging tool to detect left atrial fibrosis. However, data on the correlation between LGE-CMR detected fibrosis and low voltage areas to define fibrotic tissue is scarce. PURPOSE To assess the correlation and degree of concordance between LGE-CMR and high-density bipolar voltage mapping for the identification of left atrial abnormal tissue. METHODS Seven patients scheduled for AF ablation (including first and redo procedures) underwent a preprocedural 1.5 Tesla LGE-CMR including left atrial 3D inversion-recovery steady-state free precession sequence (ECG and respiratory triggering) 20 minutes after the injection of 0.2 mmol/kg of gadobutrol. A high-density electroanatomical voltage mapping was acquired with a 16-electrode grid configuration mapping catheter during sinus rhythm. LGE-CMR studies were analyzed off-line with an advanced image post-processing tool (ADAS 3D). Atrial wall intensity was normalized to blood pool, obtaining an image intensity ratio (IIR) value for each CMR point of the 3D model. High-density bipolar voltage maps and LGE-CMR 3D left atrial reconstruction were merged (figure, panel A). Voltage points were projected to the LGE-CMR left atrial 3D model, allowing point-by-point correlation analysis between voltage (log transformed due to non-normal distribution) with IIR. Left atrial fibrosis area and percentage were quantified using the standard cut-off values (bipolar voltage <0.5mV and IIR >1.2). We assessed the degree of concordance for normal and abnormal (fibrosis) tissue classification between the two techniques using different cut-off values (< 0.5mV and <1mV for bipolar voltage and >0.9, >1, >1.1 and >1.2 for IIR). RESULTS The average fibrosis area detected with LGE-CMR was lower than that detected with high-density bipolar voltage, using standard cut-off values (18.6 ± 5.7 cm2 vs. 40.6 ± 12.5 cm2, p = 0.13 respectively). There was a poor global point-by-point correlation between log-transformed voltage and IIR was r=-0.093, p < 0.001 (figure, panel B). The best concordance was obtained when using bipolar voltage and IIR of 0.5mV and 1.2, respectively (64.7 %; Kappa 0.101). However, the highest kappa index (0.142) for concordance was achieved with cutoff values of bipolar voltage <1mV and IIR >1, with an agreement percentage of 54.6%. CONCLUSIONS Left atrial tissue characterization between LGE-CMR and high-density bipolar voltage mapping showed significant but poor point-by-point correlation. Although the highest concordance was obtained using standard cutoff values, the Kappa index was best when applying non-standard cutoffs (1mV for bipolar voltage and >1 for IIR). Abstract Figure.

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Abstract 18572: Limitations of Endocardial Unipolar Voltage Mapping in Predicting the Epicardial Substrate

Circulation ◽

10.1161/circ.132.suppl_3.18572 ◽

2015 ◽

Vol 132 (suppl_3) ◽

Author(s):

Yalçin Gökoglan ◽

Mahmut F Günes ◽

Luigi Di Biase ◽

Carola Gianni ◽

Sanghamitra Mohanty ◽

...

Keyword(s):

Low Voltage ◽

3D Mapping ◽

Bipolar Voltage ◽

Voltage Mapping ◽

Arrhythmogenic Substrate ◽

Mapping System ◽

3D Mapping System ◽

Modest Correlation

Introduction: Bipolar voltage mapping detects areas of scar and guides ablation of VT. The role of endocardial unipolar voltage mapping is not well defined. We examined the endo-epicardial substrate in a mixed cohort of patients with structural heard disease (SHD) to determine whether an endocardial unipolar low voltage area predicts the presence and location of an epicardial scar. Results: Data from 24 consecutive patients with SHD (11 ICM, 6 NICM, 3 HCM, 2 ARVC, 1 myocarditis, 1 Brugada) with a detailed (mean points per map 200) combined endocardial-epicardial substrate mapping were retrospectively reviewed. Maps were obtained using a 3D mapping system (CARTO 3) and normal thresholds used were ≤1.5 mV for bipolar voltage, and ≤5.5 (RV) or ≤8.3 mV (LV) for unipolar voltage. Mapping was performed in the LV in 17 patients, in the RV in 6 patients, in both in 1 patient. An endocardial unipolar low voltage area was found in 21/25 maps. In 12/21 maps there was no corresponding epicardial scar, while in 3/4 cases an epicardial scar was detected despite a negative unipolar map (PPV=43%, NPV=25%, P=NS; Fig. 1). In the 9 cases with both positive endocardial unipolar and epicardial bipolar maps, the epicardial scar was found in the corresponding ventricular region of the endocardial low-voltage area, although unipolar area had a tendency to overestimate the area of the scar (115 vs 95 cm 2 ). Conclusion: In this series of patients with SHD, analysis of unipolar voltage maps could not reliably predict the epicardial arrhythmogenic substrate. There is a modest correlation between areas of endocardial unipolar low voltage and epicardial scars (57% of patients with an abnormal unipolar map had a normal epicardial substrate). Moreover, an epicardial substrate cannot be safely excluded based on a normal unipolar endocardial map. Fig. 1 Abnormal bipolar epicardial map (left) with corresponding normal unipolar endocardial map (right) in a patient with ARVC. Pink dots represent area of defragmentation.

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