Impact of atrial fibrillation burden on heart failure device alerts and therapy delivery: insights from remote monitoring in an island-based heart failure cohor

Background Atrial fibrillation (AF) is common among heart failure (HF) patients with implantable devices and contributes to HF decompensation. While device-based algorithms detect early signs of congestion, the effect of AF burden on the frequency of alerts and therapy activation (ATP/shocks) remains poorly defined in real-world monitoring, particularly in geographically isolated island populations. Purpose To evaluate the relationship between atrial fibrillation (AF) burden and device-generated alerts for heart failure or arrhythmia, and to assess its association with automatic therapy activation (ATP and shocks) in an island-based remote monitoring program. Methods We retrospectively analysed 278 HF patients with cardiac implantable electronic devices (CIEDs) followed through an island-based remote monitoring program. AF burden was defined as the percentage of time in atrial fibrillation detected by device memory. Patients were divided into low AF burden (<10%) and high AF burden (≥10%) groups. The number of device-based heart failure alerts and therapies (ATP/shocks) was compared. Group differences were tested using Mann–Whitney U, and correlations between AF burden, number of alerts, and total therapies were assessed using Spearman’s correlation. Results High AF burden patients (n=84, 30%) had a significantly greater number of HF alerts (3.2 ± 1.9 vs 1.4 ± 1.2, p < 0.001), therapies delivered (ATP + shocks: 4.7 ± 5.6 vs 1.9 ± 3.3, p = 0.004), and hospitalizations for HF (1.6 ± 0.8 vs 0.7 ± 0.4, p= 0.01). AF burden correlated strongly with both HF alert frequency (r = 0.58, p < 0.001) and total therapies (r = 0.47, p < 0.01). After adjustment for age, LVEF, and device type (ICD/CRT-D/CRT-P), AF burden remained an independent predictor of higher therapy activation (β = 0.34, p = 0.03). Conclusions Higher atrial fibrillation burden is associated with increased frequency of heart failure alerts and greater delivery of device therapies in HF patients under remote monitoring. These findings, obtained from an island-based population, highlight the importance of adapting telemonitoring strategies to geographically remote settings, where AF-related instability may lead to over-triggering of alerts and increased device activity.