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Noninvasive epi-endocardial ElectroCardioGraphic Imaging (ECGI) allows reconstruction of electrograms and high-resolution visualization of various isoparametric maps based on multichannel ECG recordings and tomography. We aimed to verify the ECGI accuracy during septal ventricular pacing in patients with pre-implanted pacemakers using the new ECGI algorithm.Methods. Ten patients underwent epi-endocardial ECGI mapping (Amycard 01C EP Lab, Amycard LLC, Russia - EP Solutions SA, Switzerland). The iterative Equal Single Layer algorithm (ESL-iterative) and a new Fast Route algorithm in combination with the vector approach (FRA-V) were used to reconstruct isopotential and correlation similarity maps. Geodesic distance between noninvasively reconstructed early activation zone and RV reference pacing sites were measured to evaluate the ECGI accuracy.Results. The mean (SD) geodesic distance between noninvasively identified sites and reference pacing sites was 22 (15) mm for the ESL-iterative and 12 (7) for FRA-V algorithms, median (25-75% IQR) - 23 (8-29) mm and 10 (8-14) mm, respectively. The accuracy of ECGI mapping based on the FRA-V algorithm was significantly better than ESL-iterative algorithm (p=0,01). A detailed visual analysis of correlation similarity and isopotential maps showed significantly more accurate localization of early activation zones using the new FRA-V algorithm.Conclusions. Our study showed the feasibility and accuracy of a novel epi-endocardial ECGI mapping approach to identify early activation zones during septal ventricular pacing using the new FRA-V algorithm. The FRA-V algorithm is significantly better for epi-endocardial ECGI mapping and shows a significant advantage of this technique compared to other non-invasive methods of topical diagnostics. Moreover, simultaneous beat-to-beat mapping of entire ventricular septum allows using this technique for pre-ablation evaluation of unstable and polymorphic ventricular arrhythmia exit sites.

Ablation of premature ventricular contractions (PVCs), relies mostly on a detailed activation mapping. This can be impossible to achieve in case of paucity or even absence of PVCs during the procedure. Pacemapping as an alternative has many limitations. We present a case of a patient with very frequent symptomatic PVCs, that on the day of the procedure had total absence of PVCs. We performed successful ablation based exclusively on electrocardiographic imaging confirmed by substrate mapping.

Aims Assess the minimal number of ECGI leads needed to obtain a good spatial resolution. Methods We enrolled 20 patients that underwent ablation of premature ventricular or atrial contractions using Carto and ECGI with AMYCARD. We evaluated the agreement regarding the site of origin of the arrhythmia between the ECGI and Carto, the area and diameter of the earliest activation site obtained with the ECGI (EASa and EASd). Based on previous studies with pacemapping, we considered a good spatial resolution of the ECGI when the EASd measured on the isopotential map was less than 18 mm. In presence of agreement the ECGI was reprocessed: a) with half the number of electrode bands (8 leads per electrode band) and b) with 6 electrode bands. Results The initial map was obtained with 23 (22-23) electrode bands per patient, corresponding to 143 (130-170) leads. Agreement rate was 85%, the median EASa and EASd were: 0.7 (0.5-1.3) cm2 and 9 (8-13) mm. With half the number of electrode bands including 73 (60-79) leads, agreement rate was 80%, the EASa and EASd were: 2.1 (1.5-6.2) cm2 and 16 (14 -28) mm. With only six electrode bands using 38 (30-42) leads, agreement rate was 55%, EASa and EASd were: 4.0 (3.3-5.0) cm2 and 23 (21-25) mm. The number of leads was a predictor of agreement with a good spatial resolution, OR (95% CI) of 1.138 (1.050–1.234), p = .002. According to the ROC curve, the minimal number of leads was 74 (AUC 0.981; 95% CI: 0.949–1.00, p Conclusion Reducing the number of leads was associated with a lower agreement rate and a significant reduction of spatial resolution. However, the number of leads needed to achieve a good spatial resolution was less than the maximal available.

Introduction. Determination of ventricular and supraventricular arrhythmias with left bundle branch block morphology (LBBB) seems to be one of the most complex diagnostic tasks when P waves are not clearly identifiable on 12-lead ECG. Previously described criteria for differential diagnosis of wide QRS arrhythmias had low accuracy especially for patients from various clinical groups and also those taking antiarrhythmic drugs. When patient’s clinical data, medical history or physical examination results are not available the number of misdiagnosis may increase leading to improper treatment. Therefore, development of new temporal and amplitude based characteristics of wide QRS complex arrhythmias with LBBB morphology in patients of any clinical groups is an important task.Methods. Twenty-eight consecutive patients with wide QRS premature beats and LBBB morphology identified by 24-hour and long-term ECG monitoring (ZAO “INCART”, Russia) were enrolled in the study. Fourteen patients had premature atrial contractions (PAC) and fourteen patients had premature ventricular contractions (PVC) during sinus rhythm. For each patient 10 typical single wide QRS complexes in 12 ECG leads were analyzed. The duration of QRS complexes, time intrinsic deflection (TID) and electrical axis of the heart were determined automatically in 12 leads ECG using KT Result 3 software (ZAO “INCART”, Russia). The experts assessed morphology of the QRS complexes and transition zone location in leads V1-V6. ROC analysis with optimal cut-off value level evaluation as well as calculation of sensitivity (SV), specificity (SP) and diagnostic accuracy (ACC) were performed for qualitative and quantitative assessment of diagnostic value of PAC and PVC amplitude and temporal characteristics. Comparison of diagnostic values of wide QRS complex morphological and temporal criteria was performed based on the AUC difference and the corresponding p-value assessment.Results. The results of study found out that V5, V1 leads were more informative for assessment of QRS complex morphology and duration while V1 and V4 leads were more informative for TID calculation in differential diagnosis of wide QRS complexes arrhythmias with LBBB morphology. PAC with aberrant conduction had the following characteristics: TID < 68 ms in V1 lead and TID < 62 ms in V4 lead; QRS < 136 ms; transition zone in the leads V5, V6; QS, rS or RS complexes (with S> R) with low-amplitude r/R waves in leads V1-V4; electric axis of the heart less than 80° in standard leads. In all cases PVCs were characterized by QRS > 160 ms and TID > 88 ms in V1-V6 leads.Conclusions. New various criteria which can improve differential diagnosis of wide QRS complexes with LBBB morphology were identified in this study. These criteria should be tested in a larger group of patients with various forms of wide QRS complex arrhythmias and different PVC localizations including information of structural heart diseases due to the small sample size in this study.Conflicts of Interest: Viktor M. Tikhonenko - CEO (Director General) of the Institute of Cardiology Technics (INCART), Saint-Petersburg, Russia.

A case report of differential and topical diagnosis of ventricular tachycardia from right ventricular outflow tract endocardial surface with ventriculoatrial retrograde conduction using non-invasive electrocardiographic imaging is presented.Conflicts of Interest: M.Chmelevsky - clinical specialist EP Solutions SA, S.Zubarev and M.Budanova - consultants EP Solutions SA.

Invasive electroanatomical mapping of polymorphic and unstable ventricular arrhythmias is a complex and laborious task. Noninvasive epi-endocardial ElectroCardioGraphic Imaging (ECGI) is a novel beat-to-beat mapping technique. The present work is a second part of single-center single-blind cross-sectional study to verify epi-endocardial ECGI accuracy. This part is particularly dedicated to investigate ECGI accuracy during right ventricular endocardial pacing followed by polygon model quality assessment and detailed analysis of cumulative effect of many different factors.Methods.37 patients with previously implanted pacemakers were enrolled in the study. All patients underwent epiendocardial ECGI mapping (Amycard 01C EP Lab, Amycard LLC, Russia - EP Solutions SA, Switzerland) during right endocardial ventricular pacing. The data obtained from torso and ECG-gated cardiac computed tomography (Somatom Definition 128, Siemens AG, Germany) were used to create three-dimensional ventricular models. Geodesic distance between noninvasively reconstructed early activate zone on the isopotential maps and RV reference pacing site were measured to evaluate ECGI accuracy for each patient.Results.The mean (SD) geodesic distance between noninvasively reconstructed and reference pacing site was 23 (14) mm for RV epicardial models and 9 (12) for RV endocardial surface of epi-endocardial models, median (25-75% IQR) - 21 (11-32) мм and 4 (2-8) mm respectively. ECGI accuracy on RV endocardial surface of epi-endocardial models was significantly better than on epicardial models (p Conclusions.The main results showed a possibility of novel epi-endocardial ECGI mapping to detect RV focal arrhythmias with high accuracy (median 3 mm) and to recognize endocardial localization with high percent of probability (more than 94%) comparable with invasive electroanatomical mapping. Therefore, this study confirms sufficient accuracy of epi-endocardial ECGI mapping technology for non-invasive topical diagnosis of RV focal arrhythmias.

Aim. The aim of study is a detection of ventricular and supraventricular wide QRS arrhythmias using complex of morphological criteria and algorithms by method of automatic analysis. Materials and methods. For 100 patients (m/f – 61/39, Me (min; max) – 44.5 (10; 85) years) of researched group the analysis of 14306 single wide ectopic complexes (QRS 120–230 ms) has been done. Wide complexes include 11028 (77%) ventricular complexes and 3278 (23%) supraventricular complexes represented by 145 different forms of QRS. For verification of arrhythmias origin transesophageal ECG recording and endocardial electrophysiological study were done. The control group included 59 patients (m/f – 25/34, Me (min; max) – 49.5 (14,85) years) with 720 wide QRS, including 467 (65%) ventricular and 253 (35%) supraventricular complexes represented by 86 forms of QRS. The criteria Drew B.J., Scheinman M.M. (1995); Wellens H.J. (1978), RWPT II (Pava LF, 2010) and the algorithms of Brugada P. (1991); Bayesian (2000); Vereckei A. (2008) were used to evaluate sensitivity, specificity and diagnostic accuracy of wide QRS complexes recognition one by one and together, using the method of Wald sequential automatic analysis (KT Result3, CJSC INCART, Russia) and method of artificial neural networks. Results. The best results for the detection of ventricular arrhythmias algorithms were demonstrated by the Brugada P., Drew B.J., Scheinman M.M. algorithm (sensitivity 86.43%, specificity 66.73%, diagnostic accuracy 82.14% in the study group, sensitivity 81.80%, specificity 73.12%, diagnostic accuracy 78.75% in the control group), and the Bayesian algorithm (sensitivity 87.81%, specificity 73.62%, diagnostic accuracy 84.72% in the study group, sensitivity 83.30%, specificity 77.08%, diagnostic accuracy 81.11% in the control group). A complex analysis of the Wald method recognized ventricular arrhythmias in the research group with sensitivity 83.11%, specificity 83.65%, diagnostic accuracy 83.23% and in the control group with a sensitivity 83.51%, specificity of 84.58% and diagnostic accuracy 83.89%. Artificial neural networks recognized ventricular arrhythmias with sensitivity 91.43%, specificity 91.30% and diagnostic accuracy 91.39% in the control group and with sensitivity 97.06%, specificity 99.39% and diagnostic accuracy 97.6% in the research group. Conclusion. Automatic analysis allows obtaining simultaneously the results of each algorithms/criteria and in combination. It significantly reduces the doctor’s work in assessing of amplitude-time characteristics of the complexes. Using artificial neural networks increases the accuracy of of ventricular and supraventricular arrhythmias recognition.

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

Introduction and aims The 12-lead ECG is highly inaccurate for localization of the site of origin of supraventricular and ventricular arrhythmias. Non-invasive mapping systems (ECGI) based on a high number of electrodes recording the electrical activity on the surface of the torso have already proven good accuracy for mapping different arrhythmic substrates. The aim of this study was to assess what is the minimal number of leads needed to obtain a precise mapping with the ECGI. Methods This study enrolled 14 patients (9 male, median age 50 (44-58) years) referred to our center for catheter ablation of premature ventricular contractions (PVC). Patients underwent pre-procedural ECGI using the epicardial and endocardial mapping system . This system uses the DICOM images from contrast computed tomography of the heart and up to 28 adhesive electrodes with 8 leads each, adding up to 224 body-surface leads. All patients underwent invasive electroanatomical mapping and ablation with the magnetic navigation system. We analysed the number of recording leads used to construct the non-invasive activation map of the PVCs and the accuracy and the spatial resolution of the map when comparing to the invasive map. We then reprocessed the exam, using progressively less leads until we only left the leads placed in the standard 12 lead ECG positions and evaluated the concordance with the invasive map as well as the spatial resolution. We considered an earliest activation site (EAS) area of 1 cm2 a good spatial resolution and using a ROC curve we calculated the minimal number of leads necessary to obtain a good spatial resolution. Results The median number of electrodes used for the initial map was 170 (138-177). Concordance between non-invasive and invasive site of origin occurred in 11 out of 14 patients. The results are presented in the Table. The minimal number of electrodes to have a good spatial resolution was 100. The area of EAS was significantly lower when using more than 100 leads, respectively 0.65 (0.5-1) cm2 versus 3 (1.6-5) cm2, p Conclusions The minimal number of leads to achieve a good spatial resolution was high. Reducing the number of leads resulted in a significant decrease in spatial resolution and a lower concordance rate. ECGI data Number of adhesive electrodes Median number of leads Amycard/Carto concordance Median area of EAS in the ECGI (cm2) Maximal nº electrodes 170 (138-177) 11/14 0.64 (0.5-0.9) 12 electrodes 76 (61-80) 11/14 1.6 (1.4-2.6) 6 electrodes (2 Ant, 2 Lat ,2 Post) 38 (32-44) 9/14 4.3 (3.2-5.4) 12 leads 12 0/14 - Ant anterior; Lat: lateral; Post: posterior; EAS: early activation site. Abstract Figure. Area of EAS according to the N of leads

Life-threatening arrhythmias are often found in heart diseases, but they are rare as clinical symptoms of Churg-Strauss syndrome. We report a case of a 66-year-old woman with symptomatic monomorphic ventricular tachycardia as the first sign of Churg-Strauss syndrome. Cardiac manifestations were the main clinical symptoms of the disease, and changes in other organs were weakly expressed. Furthermore, increased serum IgG4 level was revealed. It was the reason for the differential diagnosis with IgG4-related diseases. Echocardiography, cardiac magnetic resonance imaging, and histopathological analysis of biopsies had an important role in diagnosis. .

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.

Background It has been accepted for years that idiopathic premature ventricular contractions (PVCs) with origin in the right ventricular outflow tract (RVOT) are benign. They are thought to result from triggered activity and most studies do not describe abnormal findings during electroanatomical mapping Dispersion of ventricular repolarization is associated with the susceptibility to ventricular arrhythmias and may indicate the presence of diseased myocardium. The activation recovery interval (ARI) has been used as a surrogate measure of ventricular action potential duration and refractory period. Purpose The aim of this study was to use the new non-invasive epicardial and endocardial mapping system (NEES) to study patients with RVOT PVCs in order to evaluate the ARI in the epicardium of RVOT during sinus rhythm (SR). Methods Non-invasive mapping was performed with the NEES, based on body surface electrocardiograms of a maximum of 224 electrodes and computed tomography imaging data. Unipolar electrograms were reconstructed on the epicardial and endocardial surfaces. Patients were excluded if they had structural heart disease, previous ablation or conduction abnormalities. ARI was defined as the interval between times of minimum derivative of the QRS and the maximum derivative of the T wave in the unipolar electrograms. We evaluated the ARI map in patients with RVOT PVCs and in a control group of patients without PVCs (Figure). We assessed the maximum value of ARI (Max ARI), the minimum value of ARI (Min ARI) and the difference between the Max ARI and the Min ARI (Diff ARI). Results We studied 8 patients with RVOT PVCs and 8 patients without PVCs. The results are presented in the table. Demographic and NEES data RVOT PVCs (n=8) Control (n=8) P value* Demographic data Age in years, median (IQR) 53 (48–65) 59 (52–67) 0.536 Male gender, n (%) 4 (50) 6 (75) 0.608 NEES data Max ARI in msec, median (IQR) 285 (236–331) 228 (197–298) 0.195 Min ARI in msec, median (IQR) 176 (138–192) 216 (185–255) 0.161 ARI diff in msec, median (IQR) 111 (83–147) 15 (4–34) NEES map Conclusion In this group of patients we found a significantly higher dispersion of the ARI measurements through the epicardium of the RVOT in patients with PVCs in comparison with patients without PVCs.

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.

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.

Aims The aim of this study was to use non-invasive electrocardiographic imaging (ECGI) to study the electrophysiological properties of right ventricular outflow tract (RVOT) in patients with frequent premature ventricular contractions (PVCs) from the RVOT and in controls. Methods ECGI is a combined application of body surface electrocardiograms and computed tomography or magnetic resonance imaging data. Unipolar electrograms are reconstructed on the epicardial and endocardial surfaces. Activation time (AT) was defined as the time of maximal negative slope of the electrogram (EGM) during QRS, recovery time (RT) as the time of maximal positive slope of the EGM during T wave, Activation recovery interval (ARI) was defined as the difference between RT and AT. ARI dispersion (Δ ARI) and RT dispersion (Δ RT) were calculated as the difference between maximal and minimal ARI and RT respectively. We evaluated those parameters in patients with frequent PVCs from the RVOT, defined as >10.000 per 24 h, and in a control group. Results We studied 7 patients with frequent RVOT PVCs and 17 controls. Patients with PVCs from the RVOT had shorter median RT than controls, in the endocardium and in the epicardium, respectively 380 (239–397) vs 414 (372–448) ms, p = 0.047 and 275 (236–301) vs 330 (263–418) ms, p = 0.047. The dispersion of ARI and of RT in the epicardium was higher than in controls, Δ ARI of 145 (68–216) vs 17 (3–48) ms, p = 0.001 and Δ RT of 201 (160–235) vs 115 (65–177), p = 0.019. Conclusion In this group of patients we found a shorter median RT in the endocardium and in the epicardium of the RVOT and a higher dispersion of the ARI and RT across the epicardium in patients with PVCs from the RVOT when comparing to controls.

Background Despite the tremendous progress recently reported in ECG imaging (ECGI), some fundamental challenges are still hindering this non-invasive technology from meeting rising clinical expectations. In the present work, we address one of the major ECGI shortcomings in reconstruction of ventricular activation – the limited accuracy of endocardial and particularly septal mapping. Methods Ten CRT patients (five female, median (min-max) age – 61 (27–78) years) with previously implanted CRT devices underwent ECGI with isolated right ventricular (RV) pacing. In eight patients, the RV pacemaker lead was placed in the middle septal area of the posterior RV wall. Two subjects had a pacing lead in the anteroseptal apical segment, two at septal RVOT, two at septal junction with posterior wall and six in anterolateral segments. Lead positions were exactly known from CT scans, making the respective paced ECG sequences ideal for validation of ECGI endocardial accuracy. Non-invasive mapping was performed for single RV paced beats using original parameters of the CRT device. For non-invasive estimation of the focal origins, we considered the lead-field based fastest route algorithm (FRA) and its combination with the cardiac vector fit (FRA-V). Furthermore, we extended the resulting combined map by incorporating cardiac activation direction (FRA-V-D) provided by the cardiac dipole. Results The median (min-max) localization errors were 14 mm (7–27), 9 mm (7–28) and 11 mm (8–24) for FRA, FRA-V and FRA-V-D, respectively. Notably, in all cases at least one of the considered ECGI methods was able to correctly localize the found excitation origin on the endocardium. Conclusions This preliminary study investigates combination of the rule-based fastest route algorithm with cardiac vector fit and direction for non-invasive imaging of septal ventricular sources. The developed ECGI methodology delivers reasonable reconstruction accuracy with the 10 mm median localization error. These findings suggest potential use of ECGI for challenging clinical cases, where catheter access to the correct cardiac anatomical region plays a crucial role in the execution of the electrophysiological procedure.

ECG imaging (ECGI) is a noninvasive tool for estimating cardiac electrical activity from body surface potentials. Recently, there have been significant methodological improvements as well as a tremendous progress in the validation of ECGI reflected by an increasing number of published studies. Notwithstanding this progress, ECGI has neither been integrated into the clinical workflow concept nor achieved a clear positioning regarding its practical benefits involving cost and procedural time reduction. One of the main hurdles lies in the scarcity of high quality validation data. With this respect, the goal of the present study is to evaluate performance of three well-established inverse methods for ten cardiac resynchronization therapy (CRT) patients: the model-based fastest route algorithm (FRA), data-driven Tikhonov regularization, and a FRA-based maximum a posteriori methods were analyzed. Locations of the implanted pacing leads were exactly known from CT images, making them perfectly suited for ECGI accuracy assessment of focal activation sequences.

Recently, noninvasive electrocardiographic imaging (ECGI) has been introduced into the clinical practice. Although the ECGI diagnostic accuracy in combination with computed tomography (CT) was previously reported, the question of validating this technique with use of magnetic resonance imaging (MRI) was not solved. In this article, the method of comparison between left ventricular late activation zones determined by ECGI and sequential CT and MRI is presented. To demonstrate performance of the proposed methodology, we studied eleven patients before implantation devices for cardiac resynchronization therapy. The reconstructed three-dimensional CT and MRI models of the ventricles were merged using custom software written in Python. The median (LQ; UQ) mismatch in the obtained late activation zones was 12 (7; 13) mm. Minimal distance was 1 mm, while the maximum error was 20 mm. To conclude, this study is the first attempt to validate the accuracy of ECGI in combination with MRI against the CT-based gold standard in determining the late activation zones.

Preoperative non-invasive diagnosis of ventricular arrhythmias allows to predict ablation effectiveness, reduces the operation and radiation exposure time. Previous studies based on comparison of the early activation zone with the anatomic location of the pacemaker's tip showed high accuracy of noninvasive mapping in cardiac regions of pacemaker implantation. However, understanding of ECG imaging precision in other anatomical areas is still limited. To determine the accuracy of non-invasive mapping and examine the reconstructed excitation patterns, endocardial ventricular pacing of different myocardium areas was conducted in combination with 3D Non-Fluoroscopic Electroanatomic Mapping. Results of invasive and non-invasive mappings were analyzed and qualitative comparison of pacing point locations was performed. Better results were obtained for free walls of ventricles and worse for septum, apical parts and outflow tracts.

Background— Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging can be used to evaluate characteristics of atrial fibrosis. The novel noninvasive epicardial and endocardial electrophysiology system (NEEES) allows for the identification of sources with rotor activity. This study describes a new technique to examine the relationship between rotors and LGE signal intensity in patients with persistent atrial fibrillation (PERS) scheduled for ablation. Methods and Results— Ten consecutive patients underwent pulmonary vein isolation for persistent atrial fibrillation. LGE CMR of both atria was performed, and NEEES-based analysis was conducted to identify rotors. For each mapping point, the intracardiac locations were transferred onto an individual CMR-derived 3-dimensional shell. This allowed the LGE signal intensity to be projected onto the anatomy from the NEEES analysis. NEEES analysis identified a total number of 410 electric rotors, 47.8% were located in the left atrium and 52.2% in the right atrium. Magnetic resonance imaging analysis was performed from 10 right atria and 10 left atria data sets, including 86 axial LGE CMR planes per atrium. The mean LGE burden for left atrium and right atrium was 23.9±1.6% and 15.9±1.8%, respectively. Statistical analysis demonstrated a lack of regional association between the extent of LGE signal intensity and the presence of rotors. Conclusions— This is the first study demonstrating that the presence of rotors based on NEEES analysis is not directly associated with the extent and anatomic location of LGE signal intensity from CMR. Further studies evaluating the relationship between rotors and fibrosis in patients with persistent atrial fibrillation are mandatory and may inform strategies to improve ablation outcome.

The correct noninvasive differential diagnosis of wide complex arrhythmias is an actual problem in electrophysiology. The most part of current algorithms are based on the detailed analysis of QRS morphology using standard 12-lead ECG. However, it is well known that RR intervals and QRS duration can