UNASSIGNED: Abnormal substrate on invasive electroanatomic mapping (EAM) correlates with areas of myocardial thinning and fibrofatty replacement in Arrhythmogenic Cardiomyopathy (ACM). However, EAM parameters are absent from all sets of diagnostic criteria for ACM.
UNASSIGNED: A 41-year-old female with no significant family history was referred for evaluation of frequent premature ventricular complexes (PVCs). Twelve-lead ECG showed diffuse low-voltage QRS complexes. Holter monitor showed 28% burden of PVCs with various morphologies consistent with right ventricular (RV) inflow and outflow tract exits. Transthoracic echocardiogram revealed normal biventricular function and dimension. Cardiac magnetic resonance revealed a mildly increased indexed RV end-diastolic volume with normal RV systolic function and no dyssynchrony, akinesia, dyskinesia, or late gadolinium enhancement. Electrophysiologic study demonstrated 2 predominant PVC morphologies that were targeted with ablation, in addition to extensive abnormality with low-voltage and fractionated electrograms in the peri-tricuspid and right ventricular outflow tract free wall regions with septal sparing, suggestive of RV cardiomyopathy. Subsequent genetic testing revealed two pathogenic variants in the desmoplakin and plakophilin-2 genes, confirming the diagnosis of ACM.
UNASSIGNED: Advanced RV electropathy can precede RV structural changes in ACM. Invasive evaluation of the electroanatomic substrate should be considered in select cases even when imaging findings are not diagnostic. Future iterations of ACM guidelines may need to consider EAM substrate as one of the diagnostic criteria. A high index of diagnostic suspicion for ACM should be maintained in patients with multifocal RV ectopy.

UNASSIGNED: Predicting the origin of premature ventricular contraction (PVC) from the preoperative electrocardiogram (ECG) is important for catheter ablation therapies. We propose an explainable method that localizes PVC origin based on the semantic segmentation result of a 12-lead ECG using a deep neural network, considering suitable diagnosis support for clinical application.
UNASSIGNED: The deep learning-based semantic segmentation model was trained using 265 12-lead ECG recordings from 84 patients with frequent PVCs. The model classified each ECG sampling time into four categories: background (BG), sinus rhythm (SR), PVC originating from the left ventricular outflow tract (PVC-L), and PVC originating from the right ventricular outflow tract (PVC-R). Based on the ECG segmentation results, a rule-based algorithm classified ECG recordings into three categories: PVC-L, PVC-R, as well as Neutral, which is a group for the recordings requiring the physician\'s careful assessment before separating them into PVC-L and PVC-R. The proposed method was evaluated with a public dataset which was used in previous research.
UNASSIGNED: The evaluation of the proposed method achieved neutral rate, accuracy, sensitivity, specificity, F1-score, and area under the curve of 0.098, 0.932, 0.963, 0.882, 0.945, and 0.852 on a private dataset, and 0.284, 0.916, 0.912, 0.930, 0.943, and 0.848 on a public dataset, respectively. These quantitative results indicated that the proposed method outperformed almost all previous studies, although a significant number of recordings resulted in requiring the physician\'s assessment.
UNASSIGNED: The feasibility of explainable localization of premature ventricular contraction was demonstrated using deep learning-based semantic segmentation of 12-lead ECG.Clinical trial registration: M26-148-8.

Frequent premature ventricular contractions (PVCs) can cause a reversible form of cardiomyopathy in patients without structural heart disease. Because of the challenging nature of PVC-induced cardiomyopathy (PVICM), the mechanisms and risk factors for PVICM are still unclear. Based on the evidence from retrospective and observational studies, the risk factors for the development of PVICM, in addition to PVC exposure, include QRS duration, coupling interval and male sex. Based on animal models, abnormal calcium handling and cardiac remodeling may be the crucial mechanism underlying the development of cardiomyopathy. We have summarized the current knowledge on PVICM in this review. Understanding these mechanisms and risk factors is important for the diagnosis and management of this condition, which can lead to heart failure if left untreated.

UNASSIGNED: Mapping and radiofrequency ablation (RFA) of premature ventricular contractions (PVC) that show diurnal changes during the day, and which are rare during 3-D mapping has become very difficult. The most delayed signal mapping in the right ventricular outflow tract (RVOT) with RV apical pacing might be useful in these situations and we called this method Secret Signal Delayed Mapping (SSDM).
UNASSIGNED: To compare the classical RFA and SSDM in patients with PVC.
UNASSIGNED: A total of 60 patients with > 10% PVCs detected in 24-hour rhythm Holter recordings and admitted to the laboratory for RFA, 30 of whom underwent classical ablation according to the local activation time (LAT) and 30 of whom were included in the SSDM group, were included in our study. In patients who did not have enough PVCs during 3-D mapping, a catheter was placed in the right ventricle, and delayed signals after the ventricular electrogram (EGM) were collected by fixed pacing and such patients were included in the SSDM group.
UNASSIGNED: In all patients, PVC originated from the RVOT. The mean follow-up time of the patients was 10.2 ±1.6 months. Recurrence was detected in 11 (36.6%) patients in the LAT group and 4 (13.3%) patients in the SSDM group. Signal earlyness in LAT mapping was significantly higher in the LAT group (p < 0.001). In the SSDM group, an average of 128 ±24 delayed signals were collected, the mean delayed signal time was 77.6 ±17.7 ms. In the SSDM group, the average distance between the earliest signal on the LAT and the most delayed signal on the SSDM was 4.8 ±1.2 mm.
UNASSIGNED: In the treatment of PVCs with RFA, the SSDM method can be used in addition to classical ablation.

OBJECTIVE: We aimed to assess the acute and midterm efficacy of premature ventricular contraction (PVC) ablation guided by multielectrode and point-by-point (PbP) mapping.
RESULTS: This is a retrospective, international multicentre study of consecutive patients referred for PVC ablation in 10 hospital centres from January 2017 to December 2021. Based on the mapping approach, two cohorts were identified: the \'Multipolar group\', where a dedicated high-density mapping catheter was employed, and the \'PbP group\', where mapping was performed with the ablation catheter. Procedural endpoints, safety, and acute (procedural) and midterm efficacies were assessed. Of the 698 patients included in this study, 592 received activation mapping [46% males, median age of 55 (41-65) years]-248 patients in the Multipolar group and 344 patients in the PbP group. A higher number of activation points [432 (217-843) vs. 95 (42-185), P < 0.001], reduced mapping time (40 ± 38 vs. 61 ± 50 min, P < 0.001), and shorter procedure time (124 ± 60 vs. 143 ± 63 min, P < 0.001) were reported in the Multipolar group. Both groups had high acute success rates (84.7% with Multipolar mapping vs. 81.3% with PbP mapping, P = 0.63), as well as midterm efficacy (83.4% vs. 77.4%, P = 0.08), with no significant differences in the risk of adverse events (6.0% vs. 3.5%, P = 0.24). However, for left-sided PVC ablation specifically, there was a higher midterm efficacy in the Multipolar group (80.7% vs. 69.5%, P = 0.04), with multipolar mapping being an independent predictor of success [adjusted OR = 2.231 (95% CI, 1.476-5.108), P = 0.02].
CONCLUSIONS: The acute and midterm efficacies of PVC ablation are high with both multipolar and PbP mapping, although the former allows for quicker procedures and may potentially improve the outcomes of left-sided PVC ablation.

Premature ventricular contraction (PVC) is usually eliminated in the earliest activation site based on the conventional electrode of ablation catheter. However, the large size electrode may contain far-field potential. The QDOT MICRO ablation catheter has three micro electrodes with 0.33 mm electrode length, in addition to the conventional electrode with 3.5 mm electrode length. The micro electrodes can reflect only near-field potential. A 78-year-old with symptomatic frequent PVCs underwent catheter ablation. PVC-1 showed good pace-mapping in distal great cardiac vein (GCV). The local bipolar electrograms in the conventional electrode of ablation catheter preceded the PVC-QRS onset by 32 ms in distal GCV and 13 ms in left coronary cusp (LCC), but those in the micro electrodes preceded only by 13 ms both in distal GCV and LCC. PVC-1 was eliminated by radiofrequency (RF) application, not in distal GCV, but in LCC. PVC-2 showed good pace-mapping in LCC. The local bipolar electrograms in both the conventional electrode and the micro electrodes of ablation catheter preceded the PVC-QRS onset by 32 ms in LCC. PVC-2 was eliminated by RF application in LCC. Comparing the local electrograms of micro electrodes and the conventional electrodes may be important for identifying depth of the origin of PVCs.

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We present a case of persistent complete atrioventricular block that occurred during the diagnostic portion of a premature ventricular contractions\' radiofrequency ablation in a complex heart failure patient. The case was managed by bailout deep left ventricular septal pacing after bipolar radiofrequency elimination of premature ventricular contractions.

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