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Background: Optimization of atrioventricular (AV) intervals for cardiac resynchronization therapy (CRT) programming is typically performed in supine patients at rest, which may not reflect AV timing in other conditions.
Objective: To evaluate the effects of posture, exercise, and atrial pacing on intrinsic AV intervals in patients with CRT devices.
Methods: Rate-dependent A-V delay by exercise was a multicenter, prospective trial of patients in sinus rhythm following CRT implantation. Intracardiac electrograms were recorded to analyze atrial to right ventricular (ARV), atrial to left ventricular (ALV), and RV to LV (VV) time intervals. Heart rate was increased with incremental atrial pacing in different postures, followed by an exercise treadmill test.
Results: This study included 36 patients. At rest, AV intervals changed minimally with posture. With atrial pacing, AV interval immediately increased compared with sinus rhythm, with ARV slopes being 8.1 ± 7.7, 8.8 ± 13.4, and 6.8 ± 6.5 milliseconds per beat per minute (ms/bpm) and ALV slopes being 8.2 ± 7.7, 9.1 ± 12.8, and 7.0 ± 6.5 ms/bpm for supine, standing and sitting positions, respectively. As the paced heart rate increased, ARV and ALV intervals increased more gradually with similar trends. Interventricular conduction times changed less than 0.2 ms/bpm with atrial pacing. During exercise, the direction of change of intrinsic ARV intervals, as heart rate increased, was variable between patients with relatively small overall group changes (0.1 ± 1.4 and 0.2 ± 1.2 ms/bpm for ARV and ALV, respectively).
Conclusion: Posture and exercise have a smaller effect on AV timing compared with atrial pacing. However, individualized optimization and dynamic rate related changes may be needed to maintain optimal fusion with left ventricular (LV) stimulation.
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http://dx.doi.org/10.1111/jce.14264 | DOI Listing |
Equine Vet J
September 2025
Equine Cardioteam Ghent, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
Background: Frequent premature atrial complexes (PACs) can increase the risk of atrial fibrillation or atrial tachycardia, and pharmacological therapy can be challenging.
Objective: To report the use of three-dimensional electro-anatomical mapping of PAC originating from the right atrial free wall and treatment by radiofrequency ablation in three horses.
Study Design: Retrospective case report.
BMJ Open
September 2025
Arrhythmia Center, Chinese Academy of Medical Sciences Fuwai Hospital, Beijing, China.
Objectives: To evaluate the efficacy and safety of adding Superior Vena Cava Isolation (SVCI) to Pulmonary Vein Isolation (PVI) in patients with drug-refractory paroxysmal atrial fibrillation (PAF).
Design: Systematic review and meta-analysis of randomised controlled trials (RCTs) using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach, supplemented with Trial Sequential Analysis (TSA) to assess evidence sufficiency.
Data Sources: We searched PubMed, EMBASE, the Cochrane Library (CENTRAL) and Web of Science for relevant studies published up to 13 July 2025.
Eur J Heart Fail
September 2025
Cardiology Department, University Medical Centre Ljubljana, Ljubljana, Slovenia.
Aims: There is a lack of data from randomized clinical trials comparing treatment outcomes between conduction system pacing (CSP) modalities and biventricular pacing (BVP) in symptomatic patients with refractory atrial fibrillation (AF) scheduled for atrioventricular node ablation (AVNA). The CONDUCT-AF investigates whether CSP is non-inferior to BVP in improving left ventricular ejection fraction (LVEF) and clinical outcomes in heart failure (HF) patients with symptomatic AF undergoing AVNA.
Methods: This study is an investigator-initiated, prospective, randomized, multicentre clinical trial conducted across 10 European centres, enrolling 82 patients with symptomatic AF, HF with reduced LVEF, and narrow QRS.
Heart Rhythm O2
August 2025
Department of Cardiology, Rouen University Hospital, UNIROUEN, INSERM U1096, Rouen, France.
Background: A high burden of right ventricular pacing (RVP) increases the risk of hospitalization because of heart failure. Data on predictive factors for high burden of RVP in patients with permanent pacemaker implantation (PPI) after transcatheter aortic valve replacement (TAVR) are limited.
Objective: This study aimed to identify predictors of high RVP burden in patients with current indications for PPI after TAVR.
Heart Rhythm O2
August 2025
Department of Cardiology, Triemli Hospital Zürich, Zürich, Switzerland.
Background: Leadless pacemakers (LPs) can reduce long-term complications compared with conventional devices. However, previous studies have primarily focused on single chamber right ventricular LPs.
Objective: This study aimed to evaluate the implantation, safety, and device performance characteristics in a first real-world European use of an active fixation atrial LP for either dual chamber or single chamber pacing.