Enhanced Detection of Atrial Fibrillation and Tachyarrhythmia Differentiation Using Atrial Electrograms in Single-chamber Implantable Cardioverter-defibrillators: A Retrospective Analysis.

Atrial fibrillation (AF) is a common comorbidity among patients with implantable cardioverter-defibrillators (ICDs). The presence of AF in this patient population is associated with increased mortality and morbidity. Dual-chamber ICDs allow for atrial arrhythmia detection; however, they have higher complication rates of implantation compared to single-chamber ICDs. Recent advances have enabled single-chamber ICDs to incorporate atrial electrogram (AEGM) sensing via a floating atrial dipole, potentially improving AF detection and arrhythmia discrimination. This study evaluates the effectiveness of AEGM-enabled single-chamber ICDs in detecting AF and differentiating tachyarrhythmias compared to single-chamber ICDs without AEGM and subcutaneous ICDs (S-ICDs). A retrospective analysis was done on 128 patients who received single-chamber ICDs between 2015 and 2024. Patients were stratified into three groups: (1) ICDs with AEGM, (2) ICDs without AEGM, and (3) S-ICDs. Baseline characteristics, comorbidities, arrhythmia events, and device data were collected. Numbers of ventricular tachycardia (VT), supraventricular tachycardia (SVT), and AF events were evaluated in all three devices. Outcomes measured included the detection of new and prior AF, tachycardia classification, initiation of anticoagulation, anticoagulants, AF ablation, congestive heart failure exacerbations, hospital admissions, and mortality. Statistical comparisons were made using logistic regression analysis. ICDs with AEGM (group 1, n = 69) detected AF in 42% (n = 29) of patients, including 13% (n = 9) with newly diagnosed, asymptomatic AF. In contrast, ICDs without AEGM (group 2, n = 34) detected AF only in patients with a prior history (n = 11), with no new cases identified. S-ICDs (group 3, n = 25) detected one new AF case, confirmed by external monitoring. The detection rate of new-onset subclinical AF was significantly higher in group 1 compared to groups 2 and 3 (<i>P</i> < .05). Among nine new AF patients in group 1, anticoagulation was started in four patients, anti-arrhythmics were initiated in four patients, two patients underwent AF ablation, and one patient underwent direct current cardioversion. VT events in all groups were analyzed, and the appropriateness of the therapy was confirmed in group 1 with the availability of AEGM and in groups 2 and 3 with EGM morphology and irregularity of the R-R intervals. There was no statistical difference among the groups with VT management (<i>P</i> > .05). In conclusion, single-chamber ICDs equipped with AEGM capabilities significantly enhance the detection of asymptomatic and new-onset AF. This has important implications for the management and prevention of AF-related complications in high-risk populations. Though there was no difference in VT defibrillation among all three groups, the validation of VT/SVT/AF was much more decisive in ICDs with AEGM.