Mariona Regany-Closa

Background: Optimization of biventricular pacing for cardiac resynchronization therapy (CRT) with fusion (fusion‐optimized intervals method) has been shown to improve left ventricular remodeling. However, information on programming the atrioventricular (AV) interval during left bundle branch pacing (LBBP) is scarce. Objective: Assess with electrocardiographic imaging (ECGI) the electrical benefit of optimization of the AV interval during LBBP. Methods: Retrospective analysis of prospectively collected data. Pilot study including patients who received LBBP with CRT indication, normal AV conduction, sinus rhythm, and left bundle branch block. ECGI was used to obtain non‐invasive activation maps, ventricular activation times, and QRS widths during the optimization of the AV interval. Results: A total of 10 patients who received LBBP were included. Median age was 62 years (57–74 years), 40% were women, 20% had ischemic cardiomyopathy, and baseline LVEF was 29% (23%–36%). The baseline median QRS duration was 178 ms (168–187 ms), with a left ventricular activation time (LVAT) of 99 ms (90–109 ms), a right ventricular activation time (RVAT) of 42 ms (34–71 ms), and a total ventricular activation time (TAT) of 111 ms (105–131 ms). A non‐tailored AV programming showed a QRS measured from intrinsic deflection of 142 ms (137–149 ms); when a tailored AV was programmed, the median QRS decreased to 124 ms (116–130 ms). Ventricular activation times showed shortening with a tailored approach. Conclusion: AV interval adjustment during left bundle branch pacing may result in better resynchronization.

Introduction: Electrogram peak‐to‐peak voltage depends on atrial wall structure and mapping configuration. We evaluated the relationship between computed tomography–derived atrial wall thickness, intramyocardial fat, myocardial muscle thickness, and electrogram voltage obtained with omnipolar, bipolar, and unipolar mapping. Methods: Consecutive patients undergoing left atrial mapping during atrial fibrillation or atypical atrial flutter ablation were retrospectively included. Pre‐procedural contrast‐enhanced CT was processed with ADAS 3D to quantify left atrial wall thickness and intramyocardial fat infiltration, from which myocardial muscle thickness was derived. High‐density electroanatomical maps were spatially co‐registered with CT. Associations between anatomical parameters and peak‐to‐peak voltage were assessed, stratifying by rhythm stability. Results: Twenty patients were included. In stable rhythms, left atrial wall thickness correlated positively with voltage for all configurations, strongest for unipolar ( β = 0.38) and omnipolar ( β = 0.23) vs. bipolar mapping ( β = 0.13) (BP–UP p < 0.0001; BP–OT p < 0.01). Intramyocardial fat showed the strongest inverse association with omnipolar ( β = –0.39), compared with bipolar ( β = –0.14) and unipolar ( β = –0.01; p ≤ 0.02). After excluding fat, muscle thickness correlated positively with OT ( β = 0.30) and UP ( β = 0.30), exceeding BP ( β = 0.14; p < 0.0001). In unstable rhythms, associations were attenuated but OT remained most responsive to fat ( β = –0.20) and muscle thickness ( β = 0.11) (both p < 0.01). Conclusions: Myocardial muscle thickness is the main determinant of local atrial voltage, while intramyocardial fat contributes to voltage attenuation. OT provides the most consistent assessment of atrial wall composition, particularly under rhythm instability.

Background: Sinus node dysfunction (SND) is a well-recognized complication after orthotopic heart transplantation (OHT), particularly in recipients of biatrial anastomosis. In this setting, conventional transvenous pacing may be technically challenging due to complex post-surgical anatomy and increased infection risk. Case summary: A 36-year-old woman with restrictive cardiomyopathy underwent successful biatrial OHT. Eleven months later, she presented with persistent junctional rhythm and exertional fatigue. Electrophysiological study confirmed electrical dissociation between the donor and recipient atria with preserved atrioventricular conduction but absent sinus activity. Considering her immunosuppressed status and challenging anatomy, a leadless atrial pacemaker (Aveir AR, Abbott) was implanted under three-dimensional computed tomography (CT)–fluoroscopy fusion guidance. The device was positioned at the base of the donor right atrial appendage, achieving optimal electrical parameters. The procedure was completed without complications, and at follow-up, the patient showed complete symptom resolution and improved chronotropic response. Conclusion: This case demonstrates the feasibility and safety of CT–fluoroscopy–guided leadless atrial pacing in a post-transplant recipient with persistent SND, highlighting the value of advanced imaging for accurate spatial orientation and device deployment in complex post-surgical anatomy.

BACKGROUND: Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) is useful for identifying ventricular tachycardia (VT) substrate in patients with structural heart disease. While preprocedural LGE-CMR is widely used for planning, the role of postprocedural LGE-CMR in evaluating VT ablation success and long-term scar evolution has been less explored. This study aimed to prospectively and systematically assess the long-term evolution of scar and ablation lesions using serial postablation LGE-CMR with long-term follow-up. METHODS: This prospective study included 51 patients (mean age, 65.2±9.8 years; men, 95.8%; ischemic heart disease, 83%; left ventricular ejection fraction, 34.5±10.4%) undergoing their first substrate-based VT ablation between March 2019 and July 2020. Preprocedural LGE-CMR and 2 postprocedural scans at 3 to 6 months (CMR-1) and 18 to 24 months (CMR-2) were performed. Scar characteristics, including core scar, border zone, and conducting channels, were analyzed. VT recurrence was monitored, and factors associated with recurrence were evaluated using a Cox proportional hazards model. A Kaplan-Meier curve was used to represent the VT-free survival function. RESULTS: Core scar mass increased significantly from baseline to CMR-1 (12.2±1.5 to 19.8±1.6 g, P P P P =0.012). Evidence of favorable left ventricular remodeling was observed, with a significant reduction in left ventricular volume at CMR-2 (131.8±8.6 mL; CMR-1, 156.7±8.1 mL and 160.8±7.6 mL at baseline <0.01). CONCLUSIONS: Postablation LGE-CMR reveals durable changes in scar characteristics, with early scar evaluation at 3 to 6 months strongly associated with long-term VT recurrence. The reduction in scar heterogeneity and conducting channels is sustained over time, underscoring the usefulness of LGE-CMR for assessing ablation success. Additionally, VT ablation appeared to be associated with favorable reverse remodeling, highlighting potential benefits beyond arrhythmia control. These findings support the use of LGE-CMR for personalized management following VT ablation.

Jana Reventos-Presmanes, MSc, Andrea Cano, MSc, Eric Invers-Rubio, MSc, Berta Pellicer-Sendra, B.Eng, Jaume Serrano, B.Eng, Ernesto Zacur, PhD, Till F Alth