Incidence of atrial fibrillation in patients with an insertable cardiac monitor and symptomatic heart failure.

Aims: We aim to evaluate the incidence of atrial fibrillation (AF) in a large real-world cohort of patients implanted with an insertable cardiac monitor (ICM) who had a clinical history of symptomatic heart failure (HF) with reduced or preserved left ventricular ejection fraction (LVEF).

Methods: Patients with an ICM and a history of HF events were identified from the Optum® de-identified Electronic Health Record dataset merged with an ICM device dataset collected during 2007-2021. All ICM-detected AF episodes that were available with ≥30-s of ECG at onset were adjudicated using artificial intelligence (AI model). Episodes with AI model probability of AF ≥ 0.9 were analysed. The Kaplan-Meier incidence of AF as a function of episode duration, history of AF, and LVEF were assessed.

Results: A total of 1020 patients with ICM were identified of whom 911 had ≥180 days of follow-up and were included. According to the AI model, 358 patients had 8407 episodes of true AF. Incidence of AF at 42 months was 45.6% (44.1% vs. 46.8% in reduced vs. preserved LVEF). Incidence of new-onset AF was 23.2% (23.3% vs. 22.2% in reduced vs. preserved LVEF) in patients with no clinical history of AF. Patients with new-onset AF had a higher HF event rate compared with patients who had no clinical history of AF and did not develop AF during follow-up [OR = 2.73 (1.47-5.09); P = 0.002]. Patients with preserved LVEF had more longer duration paroxysmal AF compared with those with reduced LVEF (44.5% vs. 33.9%, P = 0.02).

Conclusions: AF was observed in almost half of patients with ICM and symptomatic HF. One-fourth of the patients had new onset AF and a higher rate of HF events compared with patients without AF. AF incidence was similar in patients with preserved and reduced LVEF.