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Aim: To describe clinical characteristics, procedural details, specific challenges, and outcomes in patients with HeartMate3™ (HM3), a left ventricular assist device system with a magnetically levitated pump, undergoing ventricular tachycardia ablation (VTA)., Methods and Results: Data were collected from patients with an HM3 system who underwent VTA in seven tertiary centres. Data included baseline patient characteristics, procedural data, mortality, and arrhythmia-free survival. The study cohort included 19 patients with cardiomyopathy presenting with ventricular tachycardia (VT) (53% with VT storm). Ventricular tachycardias were induced in 89% of patients and a total of 41 VTs were observed. Severe electromagnetic interference was present on the surface electrocardiogram. Hence, VT localization required analysis of intra-cardiac signals or the use of filter in the 40-20 Hz range. The large house pump HM3 design obscured the cannula inflow and therefore multi imaging modalities were necessary to avoid catheter entrapment in the cannula. A total of 32 VTs were mapped and were successfully ablated (31% to the anterior wall, 38% to the septum and only 9% to the inflow cannula region). Non-inducibility of any VT was reached in 11 patients (58%). Over a follow-up of 429 (interquartile range 101-692) days, 5 (26%) patients underwent a redo VT ablation due to recurrent VTA and 2 (11%) patients died., Conclusions: Ventricular tachycardia ablation in patients with HM3 is feasible and safe when done in the appropriate setup. Long-term arrhythmia-free survival is acceptable but not well predicted by non-inducibility at the end of the procedure., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

Background: The substrate for ventricular tachycardia (VT) in left ventricular (LV) nonischemic cardiomyopathy may be epicardial. We assessed the prevalence, location, endocardial electrograms, and VT ablation outcomes in LV nonischemic cardiomyopathy with isolated epicardial substrate., Methods: Forty-seven of 531 (9%) patients with LV nonischemic cardiomyopathy and VT demonstrated normal endocardial (>1.5 mV)/abnormal epicardial bipolar low-voltage area (LVA, <1.0 mV and signal abnormality). Abnormal endocardial unipolar LVA (≤8.3 mV) and endocardial bipolar split electrograms and predictors of ablation success were assessed., Results: Epicardial bipolar LVA (27.3 cm 2 [interquartile range, 15.8-50.0]) localized to basal (40), mid (8), and apical (3) LV with basal inferolateral LV most common (28/47, 60%). Of 44 endocardial maps available, 40 (91%) had endocardial unipolar LVA (24.5 cm 2 [interquartile range, 9.4-68.5]) and 29 (67%) had characteristic normal amplitude endocardial split electrograms opposite the epicardial LVA. At mean of 34 months, the VT-free survival was 55% after one and 72% after multiple procedures. Greater endocardial unipolar LVA than epicardial bipolar LVA (hazard ratio, 10.66 [CI, 2.63-43.12], P =0.001) and number of inducible VTs (hazard ratio, 1.96 [CI, 1.27-3.00], P =0.002) were associated with VT recurrence., Conclusions: In patients with LV nonischemic cardiomyopathy and VT, the substrate may be confined to epicardial and commonly basal inferolateral. LV endocardial unipolar LVA and normal amplitude bipolar split electrograms identify epicardial LVA. Ablation targeting epicardial VT and substrate achieves good long-term VT-free survival. Greater endocardial unipolar than epicardial bipolar LVA and more inducible VTs predict VT recurrence.

Purpose: An important attenuation of the atrial signal recorded with mini-electrodes (ME) embedded in an 8-mm tip was associated with a transmural radiofrequency lesion. Our aim was to assess if parameters obtained from ME or conventional bipoles before applications predict successful atrial lesions., Methods: We prospectively included 33 consecutive patients undergoing cavotricuspid isthmus (CTI) ablation. Electrogram voltages and pacing thresholds were measured with ME and conventional bipoles before and after radiofrequency (RF) applications. The time before the loss of capture during applications was recorded. Lesions were considered successful, in accordance with preclinical data, if ME voltage decreased > 54%., Results: Of 207 applications, 107 could be analyzed. During applications, voltages decreased more in the ME than in the conventional bipoles (66.8 ± 26.1% vs 37.5 ± 42.5%, P = 0.001). Likewise, pacing threshold increased significantly more using the ME (86.3 ± 22.9% ME, 52.6 ± 35.6% conventional, P = 0.001). ME pre-ablation voltages were significantly higher and pacing thresholds significantly lower in successful lesions (voltage 0.88 ± 0.71 vs 0.26 ± 0.18 mV, P = 0.0001; threshold 1.6 ± 1.7 vs 2.8 ± 3.0, P = 0.04). Neither of these parameters with conventional bipoles nor time to loss of capture showed differences. A ME voltage > 0.33 mV and a pacing threshold < 1.5 mA predicted a successful lesion with 0.78 and 0.6 sensitivity and 0.78 and 0.59 specificity., Conclusions: Certain pre-ablation parameters derived from ME such as electrogram voltage and pacing threshold differ from those obtained by a conventional configuration and can predict a successful atrial lesion.

Background: The presence of epicardial connections (ECs) between pulmonary veins (PVs) and other anatomic structures may hinder PV isolation. In this study, we analyzed their prevalence, location, associated factors, and clinical implications., Methods: Five hundred thirty-four consecutive patients with atrial fibrillation undergoing radiofrequency ablation were included. We considered that an EC was present if: (1) the first pass around the PV antrum did not produce PV isolation and (2) subsequent atrial activation during PV pacing showed that the earliest site was located away from the ablation line and later activation sites were observed near the ablation line. Clinical and electrophysiological variables were collected from all patients. Patients were followed during 12.9±9.4 months, and any documented atrial tachyarrhythmia after the 3-month blanking period was classified as a recurrence., Results: Out of the 534 patients included, 72 (13.5%) were found to have 81 ECs. There was a significant association between the presence of ECs and structural heart disease (15.3% in patients without ECs versus 36.5% in patient with ECs; P <0.001) and patent foramen ovale (4.6% versus 13.5%; P =0.002). The presence of a left common trunk was significantly associated with the absence of ECs (29.6% in patients without ECs versus 16.2% in patients with ECs; P =0.014). Patients with ECs had lower acute success in PV isolation compared with patients without ECs (99.1% versus 86.1%; P <0.001). After adjusting for age, sex, type of atrial fibrillation, left atrium area, hypertension, structural heart disease, presence of left common trunk, patent foramen ovale, and time for atrial fibrillation diagnosis to the ablation, we found a significantly higher risk of atrial tachyarrhythmia recurrences in patients with ECs compared with patients without ECs (hazard ratio, 1.7 [95% CI, 1.1-2.9]; P =0.04)., Conclusions: ECs between PVs and other adjacent structures are frequent in patient with atrial fibrillation (prevalence: 13.5%). Structural heart disease and a patent foramen ovale are strongly associated with the presence of ECs. ECs reduce the acute and chronic success of PV isolation.

Background: Finding the conduction gaps in redo PV isolation procedures is challenging, and several maneuvers have been described. In the present study, we analyze the pace and map (P&M) maneuver [atrial mapping during pulmonary vein (PV) pacing] to locate the gaps in redo PV isolation procedures., Methods: Consecutive patients undergoing a second PV isolation procedure at a single institution over a 4-year period were included. For the last 2 years, all the patients (n = 38) studied underwent PV isolation based on the P&M maneuver and were compared to the previous patients (n = 45). The atrial side of the ablation line was mapped with the ablation catheter during PV pacing, and the earliest site was considered a gap site., Results: Shorter radiofrequency time was required to obtain PV isolation in the P&M group (485 ± 374 vs. 864 ± 544 s; p < 0.001), which remained significant after adjusting for the number of reconnected PVs (p = 0.01). We did not find significant differences in the procedure duration (106 ± 46 vs. 112 ± 53 min; p = 0.57) and arrhythmia recurrence during 1-year follow-up (26.6 vs. 28.9%; p = 0.82) after adjusting for several confounding factors (HR 1.32; 95% CI 0.5-3.4; p = 0.57)., Conclusions: P&M is a simple maneuver to identify the gaps in ablation lines around the PV. It remains efficacious in redo procedures despite the difficulties in localizing the ablation lines performed in the first procedure. The P&M maneuver reduced the radiofrequency time required to isolate the PV without compromising the efficacy.

Catheter-based ablation of isthmus-dependent common atrial flutter results in very high success rates and almost no complications. However, bidirectional conduction block through the isthmus may be challenging in a small percentage of patients regarding the use of high power and high temperature settings during radiofrequency delivery. Anatomical and physiological circumstances may be the reason for such difficulties to achieve bidirectional block at the cavo-tricuspid isthmus. However, in the present case we show edema formation after multiple shots of radiofrequency delivery at the cavo-tricuspid isthmus, which complicates the achievement of bidirectional conduction block., (Copyright © 2013 Instituto Nacional de Cardiología Ignacio Chávez. Published by Masson Doyma México S.A. All rights reserved.)