Electrocardiographic imaging a valid tool or an inaccurate toy?

Funding Acknowledgements

Type of funding sources: Private hospital(s). Main funding source(s): Learning Health

Background and aim

Electrocardiographic imaging (ECGI) is capable of performing an activation map with a single beat. However, previous studies using the epicardial-only system, have suggested a bad accuracy for the assessment of the epicardial breakthrough. Recent systems using endo-epicardial analysis have shown promising results. The aim of this study was to assess the accuracy and reproducibility of two endo-epicardial ECGI systems using different cardiac sources one based on the extracellular-potential, and the other on the equivalent double layer model, respectively the AMYCARD (EP Solutions SA, Switzerland) and VIVO (Catheter Precision, NJ USA) systems.

Methods

We studied 11 consecutive patients referred for ablation of frequent idiopathic premature ventricular contractions at our center that had an ECGI performed using both systems on the same day. The AMYCARD system uses a dense array of body-surface electrocardiograms with up to 224 leads and VIVO uses just the 12-leads ECG. Both systems use a patient-specific heart torso geometry obtained with a CT-scan or cardiac magnetic resonance. The localisation of the PVCs based on ECGI was done using a segmental model with 22 segments on the left ventricle, to include the classical 17 segment model plus the aortic cusps and the papillary muscles, and 12 segments on the right ventricle including 4 on the right ventricular outflow tract (RVOT): (anterior, lateral, right septum and left septum). A perfect match was defined as a predicted location within the same anatomic segment, whereas a near match as a predicted location within the same segment or a contiguous one.

Results

The median (Q1-Q3) number of leads used for the AMYCARD was 131 (118-144). Seven patients underwent ablation and in 4 ablation is pending. The predicted locations and the ablation site are depicted on the Table. We found a perfect match between both systems in 73% (Figure) and near match in 91% of cases. In patients that underwent ablation the systems localised the site of origin of the PVCs within the same segment or the contiguous segment in all patients with VIVO and in six out of seven with AMYCARD.

Conclusions

ECGI is an accurate diagnostic tool with reproducible results regardless the cardiac source used for analysis.

Assessment of activation duration across the right ventricular outflow tract in patients with premature ventricular contractions using noninvasive electrocardiographic mapping: a validation study

Funding Acknowledgements

Type of funding sources: Private hospital(s). Main funding source(s): Learning Health

Introduction

Previous studies have reported that wavefront propagation speed across the right ventricular outflow tract (RVOT) can distinguish premature ventricular contractions (PVCs) with a RVOT origin from PVCs with a left ventricular outflow tract (LVOT) origin.

Aim

Validate the non-invasive electrocardiographic mapping (ECGI) for assessment of RVOT activation duration (AD) during PVCs and assess its value as a predictor of the origin of the PVCs.

Methods

We studied 18 consecutive patients, 8 males, median age 55 (35-63) years that underwent ablation of frequent (> 10.000 per 24 h) idiopathic PVCs with inferior axis, that had and an ECGI performed before ablation and the RVOT mapped in PVC. The ECGI was performed with the Amycard system, and invasive mapping was performed with the Carto or Ensite system. Isochronal activation maps of the RVOT in PVC were obtained with the activation direction method (ADM) of the ECGI, and with the Carto and Ensite systems. Total RVOT AD was measured as the time interval between the earliest and the latest activated region. Agreement between the two methods was performed using a Bland-Altman plot and linear regression . The cutoff value of AD to predict PVC origin was calculated with ROC curve.

Results

PVCs originated from the RVOT in 11 (61%) patients. The median (Q1-Q3) RVOT AD measured with ECGI was 54 (39-68) ms and with invasive map 57 (36-70) ms. The agreement between both methods was good with an R2 of 0.747, p<0.0001. Figure displays the Bland-Altman plot (panel A), the linear regression plot (panel B). and two examples of the ECGI isochronal map (panel C). The AD was significantly higher in PVCs from the RVOT vs LVOT, both with ECGI and Carto, respectively 62 (58-73) vs 37 (33-40) ms, p<0.0001 and 68 (60-75) vs 34 (30-40) ms, p<0.0001. The cutoff value of 43 ms for AD measured with ECGI, predicted the origin of the PVCs with a sensitivity and specificity of 100%.

Conclusions

We found good agreement between ECGI and Carto. The AD obtained with ECGI was accurate to predict the origin of the PVCs.

Find me if you can: lessons learned using the novel cartofinder algorithm in a routine workflow for catheter ablation of atrial fibrillation

Funding Acknowledgements

Type of funding sources: None.

Background

CARTOFINDER allows for a simultaneous and automated detection of repetitive focal and rotational activations during electroanatomical mapping using a multi-electrode catheter in patients with atrial fibrillation (AF).

Aim

This study aimed to validate the CARTOFINDER algorithm for the detection of potential drivers for AF under routine clinical conditions and to access the effects of PVI and additional substrate modification on regions of interests (ROI) from CARTOFINDER mapping.

Methods

Forty-four consecutive patients underwent AF ablation for persistent AF using a 3D-mapping system with the novel integrated CARTOFINDER module. All patients presented with persistent AF and mapping was performed using a multi-electrode catheter. The ablation workflow was divided into the following steps: 1. 3D reconstruction of the right (RA) and left atrium (LA). 2. Identification of the individual ROIs separated for focal and rotational activity in the RA and LA. 3. Ablation index guided pulmonary vein isolation (PVI). 4. Repeat mapping for ROIs in the RA and LA. 5. Direct current electrical cardioversion. 6. Confirmation of persistent PVI and bipolar ultra-high density mapping of the RA and LA followed by substrate modification if there was evidence for local bipolar low-voltage in the LA.

Results

Acute PVI was achieved in all patients (100%). In 28% of these patients additional LA substrate modification was performed. AF termination was observed in 4 patients. Mean procedure duration was 137 ± 30 min, mapping time for ROIs in the RA was 8 ± 5 min and 11 ± 5 for the LA, respectively. A mean number of 149 ± 82 ROIs were revealed from CARTOFINDER. In the LA, focal activity was predominantly observed inside the LA appendage (LAA) and in close relationship to the pulmonary vein ostia. The majority of rotational activities was found along the mitral valve annulus. In the RA, the majority of ROIs was found at the septum and in close relationship to the RA appendage. During re-mapping for ROIs after AF ablation we observed the elimination of ROIs close to the linear ablation set for PVI. In addition, rotational activity could not be re-identified at repeat mapping.

Conclusions

ROIs could be discriminated and visualized utilizing CARTOFINDER in all patients. These ROIs might potentially be an additional and individual ablation target beyond PVI in patients with persistent AF.

Evaluation of noninvasive electrophysiological imaging accuracy for focal atrial arrhythmias

Background

High accuracy of noninvasive electrocardiographic imaging (ECGI) has recently been shown for topical diagnostics of ventricular arrhythmias. However, the precision of diagnostics of atrial focal arrhythmias requires clarification. To estimate the accuracy of ECGI for premature atrial contraction (PAC) we performed atrial pacing in patients with CRT system and compared early activation zone (EAZ) with pacemaker's tip location.

Purpose

To determine the accuracy of ECGI for focal atrial arrhythmias using atrial pacing.

Methods

Twenty-six patients (m/f – 18/9), age (min–max) 52 (26–78) with CRT system and pacemaker's tip location in the right atrium (RA) appendage underwent ECGI (“Amycard 01C”) in combination with CT or MR imaging. Thirty-four atrial pacing (mono- and bipolar) was performed in all patients using standard amplitude 1.5–3.8 mV. Epi-/endocardial polygonal heart models were created and isopotential maps were calculated. The distance between EAZ and the pacemaker's tip were measured for ECG recordings without using the isoline filter on endocardial surface (Fig. 1) as well as for epicardial surface. The time between epicardial and endocardial EAZ breakthrough was calculated also.

Results

On endocardial surface the EAZ was located in RA appendage, the base of superior cava vena or superior lateral RA wall. The distance (mm) (Me (min; max)) between EAZ and the pacemacer's tip was 28 (6; 68). For epicardial surface in most cases the EAZ was also located in RA appendage, the base of superior cava vena or superior lateral RA wall. In two cases the EAZ was located in inferior septal RA wall, in one case - in superior septal RA wall and in five cases the EAZ was undetectable. The distance between EAZ and the pacemacer's tip was 22 (6; 48). The time (ms) (Mean; Me (min; max)) between EAZ of the endocardial and epicardial surfaces was 16; 7 (0; 68).

Conclusion

ECGI allows to assess the location of focal atrial arrhythmias on endocardial surface and sometimes on epicardial surface also within the three segments. The results of this study revealed that accuracy of ECGI for atrial arrhythmias is worse than for ventricular arrhythmias. However, it is better on epicardial surface of atrium when EAZ can be determined.

Funding Acknowledgement

Type of funding source: None

P5696The first results from multicentre study of noninvasive epi-endocardial panoramic mapping of ventricular arrhythmias

Background

A noninvasive epi-endocardial panoramic mapping is a promising ECG Imaging technology alternative to catheter-based invasive methods. Some unstable ventricular arrhythmias arising from complex anatomic sites render mapping and ablation difficulties with conventional approach.

Objective

To assess the use of a noninvasive panoramic mapping for diagnosis and localization of ventricular arrhythmias.

Methods

35 patients (20 male, median (25–75%) age – 35 (12–60) years) with polymorphic premature ventricular contractions (PVCs) and 3–5 different QRS morphologies (1500–19000 per day) or monomorphic ventricular tachycardia (VT) were enrolled in the study. Up to 224 body surface electrodes were connected to the noninvasive epi-endocardial electrophysiological system for multichannel ECG recording followed by computed tomography of the heart and torso. The body-surface ECG data were processed using inverse-problem solution software in combination with realistic 3D anatomical models of the heart and torso. The earliest site of activation were determined on isopotential maps for each QRS morphology. On the same day patients underwent catheter ablation of one or two dominant PVC morphologies using 3D electroanatomical mapping system. The site of successful catheter ablation served as final confirmation. Afterwards, electroanatomical maps were exported from Carto 3 system and compared with noninvasive maps using custom written Python-based software.

Results

In total 47 similar PVC morphologies in 30 patients were mapped using noninvasive and invasive electroanatomical mapping systems, 34 (72%) PVCs were correctly diagnosed and 13 (28%) did not accurately correspond with sites of radiofrequency ablation. In 2 patients with four PVC morphologies an early activation zones were determined as a breakthrough from epi and endocardial surface using noninvasive activation maps.

Conclusion

Non invasive epi-endocardial panoramic mapping technology is a novel diagnostic method which can be used as an additional pre-procedural tool for topical diagnosis of polymorphic PVCs.

P6566Noninvasive Panoramic Mapping of Phase Singularities with Signal Complexity Analysis in Patients with Persistent Atrial Fibrillation

Background

An assessment of positive outcome probability of ablation therapy based on the comprehensive signal complexity analysis is a promising working hypothesis while electrocardiographic imaging (ECGI) can detect and visualize zones of phase singularities (PS) associated with stable sources of atrial fibrillation (AF).

Methods

Ten consecutive patients with persistent AF (three female, median (min–max) – 63.5 (45–75) years) underwent ECGI using “Amycard 01C EP lab” system with cardiac MRI (1.5-T Magnetom Avanto) followed by pulmonary vein isolation. Each T-Q segment with a length >800 ms during AF was processed to find PS. Sites with rotations around stable pivot points were considered as PS and then marked and visualized on the reconstructed anatomical 3D atrial model. Finally, a signal complexity cluster analysis was performed to define and depict phase-aggregation zones.

Results

ECGI analysis identified a total number of 410 PS, with 196 (47.8%) occurring in the LA and 214 (52.2%) in the RA. The median (25–75% IQR) number of revealed PS per patient was n=20 (14–30) for RA and n=20 (11–22) for the LA. The majority of the PS in the LA was located on the inferior wall n=66 (min-max 1–17). In eight patients, comprehensive signal complexity analysis revealed stability of phase-clustered zones over time. The mean number (min-max) of PS in a clustered area was 10 (6–15). In two patients, PS were distributed disordered on the entire LA and RA surface.

Distribution of phase singularities

Conclusions

This is the first clinical study demonstrating signal complexity analysis capability of clustering noninvasively mapped PS and relating them to specific atrial anatomical regions. Thereby obtained clusters may be a potential zones of conduction block, and could contribute to a better understanding of the temporal AF complexity.

P2567First experience of non-invasive and invasive activation maps merge in carto system for topical diagnosis of focal arrhythmias

Background

Correct preoperative topical diagnostics of atrial and ventricular arrhythmias allows for operation time reduction by facilitating the ablation target localization, especially in case of several ectopic sources.

Purpose

To implement a non-invasive electrocardiographic imaging (ECGI) technique in CARTO system for aiming at topical diagnostics of focal arrhythmias improving.

Methods

Twelve patients (m/f – 10/2, age (min–max) – 50,5 (32–71)) with focal arrhythmias underwent ECGI in combination with CT or MR imaging. Two subjects had atrial premature contractions (PAC), while ten patients suffered from ventricular premature contractions (PVC) with indications for ablation. Before the ablation procedure Carto LAT mapping was performed in all patients. Using ECGI epi-/endocardial polygonal models of the heart were created, isopotential and activation maps were calculated, uploaded into the Carto system and merged with the CARTO FAM models (Figure 1).

Results

For six patients with PVC and two patients with PAC, earliest activation zones (EAZs) anatomical locations obtained by invasive and non-invasive methods were the same (RVOT septum, RVOT lateral-anterior and RV lateral-basal walls, right aortic cusp, LVOT, coronary sinus (CS), CS ostium, RA posterior wall), and arrhythmias ablation was successful. Two patients featured coherent EAZs (RV lateral-basal wall and RVOT septum) but a negative ablation outcome. In one patient, EAZs were situated in different anatomical regions: CARTO showed the PVC EAZ in RV septum, whereas Amycard system identified endocardial surface of lateral-basal RV wall. In this patient, PVC was ablated partially. For another patient with MRI late enhancement area in LV lateral wall the EAZs were in the same LV segment but with mismatch in epi/endocardial surface.

Conclusion

Non-invasive and invasive activation maps merge can improve localization of ablation targets in focal arrhythmias, potentially increasing effectiveness of the EP procedure and reducing operation time.