Arrhythmia Burden and Clinical Responses Under Continuous Monitoring in Heart Failure

Background: Arrhythmia burden in ambulatory patients with symptomatic heart failure (HF) without cardiac implantable electronic devices (CIEDs) is not well defined, and it remains uncertain whether device-guided remote congestion management modifies arrhythmia occurrence. Objectives: The goal was to assess whether arrhythmia burden differed between randomized congestion-management strategies and characterize the occurrences and associations of insertable cardiac monitor (ICM)-detected arrhythmias with therapeutic actions and clinical events. Methods: In ALLEVIATE-HF, patients with NYHA functional class II-III HF with any ejection fraction (EF) and a recent HF event, without prior CIEDs, underwent ICM implantation and were randomized to ICM-guided, physician-directed, nurse-facilitated congestion management or usual care. In both arms, arrhythmia data were accessible to investigators, and arrhythmia-related management was clinician directed. Arrythmia occurrence was estimated using Kaplan-Meier methods. Associations with therapeutic interventions and clinical events were evaluated using time-varying Cox models. Results: The analysis included 711 patients (mean age 70.5 ± 10.4 years; 45.7% women; mean follow-up 17.3 ± 8.9 months); 67.9% had HF with preserved EF, and 60.2% were NYHA functional class II at baseline. During the 13-month randomized phase, arrhythmia occurrence rate did not differ between the study arms. The 3-year overall occurrence of atrial fibrillation (AF) was 66.6%, with an incidence of new-onset AF of 25.4%. Bradyarrhythmia occurred in 47.1% of patients, and ventricular tachycardia or fibrillation (VT/VF) in 20.1%. ICM-recorded arrhythmia was associated with subsequent increase in arrhythmia-related interventions (HR: 3.81; VT/VF and VT/VF-related interventions, HR: 7.04; AF and AF-related interventions, HR: 3.28; bradyarrhythmia and bradyarrhythmia-related interventions, HR: 7.22; all P < 0.001). ICM-recorded arrhythmia was associated with increased risk of all-cause hospitalization (HR: 1.79; P < 0.001) and HF events (HR: 1.69; P = 0.003). Therapeutic CIED implantation and ablation occurred in 22.7% and 26.1%, respectively. Bradyarrhythmias were more common in patients with EF ≥50%, whereas VT/VF occurred more frequently in EF <50%; AF occurrence was similar between EF groups. Conclusions: In ambulatory patients with recent symptomatic HF events, arrhythmia burden was not modified by the study protocol–directed, congestion-management strategy. Continuous ICM monitoring revealed a high burden of clinically meaningful arrhythmias that were associated with clinical events and therapeutic interventions.