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BACKGROUND: Atrial fibrillation (AF) and ventricular fibrillation (VF) episodes exhibit varying durations, with some spontaneously ending quickly while others persist. A quantitative framework to explain episode durations remains elusive. We hypothesized that observable self-terminating AF and VF episode lengths, whereby durations are known, would conform with a power law based on the ratio of system size and correlation length (L/ξ). METHODS: Using data from computer simulations (2-dimensional sheet and 3-dimensional left-atrial), human ischemic VF recordings (256-electrode sock, n=12 patients), and human AF recordings (64-electrode basket-catheter, n=9 patients; 16-electrode high definition-grid catheter, n=42 patients), conformance with a power law was assessed using the Akaike information criterion, Bayesian information criterion, coefficient of determination (R², significance=P<0.05) and maximum likelihood estimation. We analyzed fibrillatory episode durations and L/ξ, computed by taking the ratio between system size (L, chamber/simulation size) and correlation length (xi, estimated from pairwise correlation coefficients over electrode/node distance). RESULTS: In all computer models, the relationship between episode durations and L/ξ was conformant with a power law (Aliev-Panfilov R²: 0.90, P<0.001; Courtemanche R²: 0.91, P<0.001; Luo-Rudy R²: 0.61, P<0.001). Observable clinical AF/ VF durations were also conformant with a power law relationship (VF R²: 0.86, P<0.001; AF basket R²: 0.91, P<0.001; AF grid R²: 0.92, P<0.001). L/ξ also differentiated between self-terminating and sustained episodes of AF and VF (P<0.001; all systems), as well as paroxysmal versus persistent AF (P<0.001). In comparison, other electrogram metrics showed no statistically significant differences (dominant frequency, Shannon Entropy, mean voltage, peak-peak voltage; P>0.05). CONCLUSIONS: Observable fibrillation episode durations are conformant with a power law based on system size and correlation length. [ABSTRACT FROM AUTHOR]

Background: To mitigate the risk of dyssynchrony‐induced cardiomyopathy, international guidelines advocate His bundle pacing (HBP) with a ventricular backup lead prior to atrioventricular node ablation in treatment‐refractory atrial fibrillation and normal left ventricular ejection fraction. As a result of concerns with long‐term pacing parameters associated with HBP, this case series reports an adopted strategy of HBP combined with deep septal left bundle branch area pacing (dsLBBAP) in this patient cohort, enabling intrapatient comparison of the two pacing methods. Methods and Results: Eight patients aged 72 ± 10 years (left ventricular ejection fraction 53 ± 4%) underwent successful combined HBP and dsLBBAP implant prior to AV node ablation. Intrinsic QRS duration was 118 ± 46 ms. When compared to dsLBBAP, HBP had lower sensed ventricular amplitude (2.4 ± 1.1 vs. 15 ± 5.3 V, p =.001) and lower lead impedance (522 ± 57 vs. 814 ± 171ohms, p =.02), but shorter paced QRS duration (101 ± 20 vs. 119 ± 17 ms, p =.02). HBP pacing threshold was 1.0 ± 0.6 V at 1 ms pulse width, and dsLBBAP pacing threshold was 0.5 ± 0.2 V at 0.4 ms pulse width. Five patients underwent cardiac CT showing adequate dsLBBAP ventricular septal penetration (8.6 ± 1.3 mm depth, 2.4 ± 0.5 mm distance from left ventricular septal wall). No complications occurred during a mean follow‐up duration of 121 ± 92 days. Conclusions: Combined HBP and dsLBBAP pacing is a feasible approach as a pace and ablate strategy for atrial fibrillation refractory to medical therapy. [ABSTRACT FROM AUTHOR]

Background: Forward prediction of atrial fibrillation (AF) termination is a challenging technical problem of increasing significance due to rising AF presentations to emergency departments worldwide. The ability to non-invasively predict which AF episodes will terminate has important implications in terms of clinical decision-making surrounding treatment and admission, with subsequent impacts on hospital capacity and the economic cost of AF hospitalizations., Methods and Results: MEDLINE, EMCare, CINAHL, CENTRAL, and SCOPUS were searched on 29 July 2023 for articles where an attempt to predict AF termination was made using standard surface ECG recordings. The final review included 35 articles. Signal processing techniques fit into three broad categories including machine learning (n = 14), entropy analysis (n = 12), and time-frequency/frequency analysis (n = 9). Retrospectively processed ECG data was used in all studies with no prospective validation studies. Most studies (n = 33) utilized the same ECG database, which included recordings that either terminated within 1 min or continued for over 1 h. There was no significant difference in accuracy between groups (H(2) = 0.058, p-value = 0.971). Only one study assessed recordings earlier than several minutes preceding termination, achieving 92% accuracy using the central 10 s of paroxysmal episodes lasting up to 174., Conclusions: No studies attempted to forward predict AF termination in real-time, representing an opportunity for novel prospective validation studies. Multiple signal processing techniques have proven accurate in predicting AF termination utilizing ECG recordings sourced from a database retrospectively., (© 2024 The Author(s). Annals of Noninvasive Electrocardiology published by Wiley Periodicals LLC.)

Aims: There are conflicting data as to the impact of procedural volume on outcomes with specific reference to the incidence of major complications after catheter ablation for atrial fibrillation. Questions regarding minimum volume requirements and whether these should be per centre or per operator remain unclear. Studies have reported divergent results. We performed a systematic review and meta-analysis of studies reporting the relationship between either operator or hospital atrial fibrillation (AF) ablation volumes and incidence of complications., Methods and Results: Databases were searched for studies describing the relationship between operator or hospital AF ablation volumes and incidence of complications which were published prior to 12 June 2020. Of 1593 articles identified, 14 (315 120 patients) were included in the meta-analysis. Almost two-thirds of the procedures were performed in low-volume centres. Both hospital volume of ≥50 and ≥100 procedures/year were associated with a significantly lower incidence of complications compared to <50/year (4.2% vs. 5.5%, OR = 0.58, 95% CI 0.50-0.66, P < 0.001) or <100/year (5.5% vs. 6.2%, OR = 0.62, 95% CI 0.53-0.73, P < 0.001), respectively. Hospitals performing ≥50 procedures/year demonstrated significantly lower mortality compared with those performing <50 procedures/year (0.16% vs. 0.55%, OR = 0.33, 95% CI 0.26-0.43, P < 0.001). A similar relationship existed between proceduralist volume of <50/year and incidence of complications [3.75% vs. 12.73%, P < 0.001; OR = 0.27 (0.23-0.32)]., Conclusion: There is an inverse relationship between both hospital and proceduralist AF ablation volume and the incidence of complications. Implementation of minimum hospital and operator AF ablation volume standards should be considered in the context of a broader strategy to identify AF ablation Centers of Excellence., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

The case is described of a successful MitraClip procedure performed on an 88-year-old patient with severe mitral regurgitation (MR), five years after she had undergone mitral valve repair using the Alfieri surgical procedure. It is suggested that the MitraClip procedure is an option in patients with severe MR persisting after the Alfieri procedure. Video 1: Transesophageal echocardiography before the MitraClip procedure. Severe mitral regurgitation with preserved left ventricular systolic function. The main regurgitant jet originates from the medial commissure. Video 2: Transesophageal echocardiography: clip placement and jet reduction. A single clip placement on the medial portion of the mitral valve, resulting in elimination of the medial jet and reduction of the overall mitral regurgitant jet from grade 4+ to grade 2+.