Incidence of atrial fibrillation detected by an insertable cardiac monitor in a large real-world cohort of heart failure patients with reduced and preserved ejection fraction
Authors: Shahzeb Khan M , Kahwash R , Zile M R , Sarkar S , Van Dorn B , Gerritse B , Butler J 
Published: October 2024

Abstract

Background
Subcutaneous implantable cardiac monitors (ICM) have the capability to detect atrial fibrillation (AF) episodes with high degree of accuracy [1].

Objective
We investigated the incidence of AF in patients implanted with an ICM and a clinical history of heart failure (HF) with reduced or preserved left ventricular ejection fraction (LVEF).

Methods
Patients with history of HF admissions who were implanted with an ICM were identified from the aggregated and de-identified electronic health record (EHR) database during 2007-2021. The device collected data were merged with the EHR data to create a de-identified database of real-world patients. Patients were included if they had ≥180 days of device follow-up. ICMs detect AF based on incoherence of RR intervals and absence of single p-wave between two R-waves [1]. All ICM detected AF episodes stored with at least 30 seconds of ECG at onset were adjudicated using an artificial intelligence (AI) model. The AI model was previously trained and validated using over 60K manually adjudicated episodes and was shown to have an accuracy of over 97% [2]. ICM detected AF episodes with AI model based true probability of AF ≥ 0.9 was analyzed. The Kaplan-Meier incidence curves for AF incidence as a function of episode duration, clinical history of AF, and LVEF are reported.

Results
A total of 1020 LINQ ICM patients with history of HF admission prior to implant were identified from the deidentified real-world dataset. LVEF was available in 889 (87%) patients, of whom 394 (44%) had EF &lt;50%, and 495 (56%) had EF≥50%. NYHA class was available in 296 (29%) patients, of whom 39 (13%) were class I, 126 (43%) were class II, 112 (38%) were class III, and 19 (6%) were class IV. Patients had an average age of 68±13 years with 52% being males and had clinical history of hypertension in 95%, diabetes in 56%, coronary artery disease in 75%, AF in 57%, stroke/TIA in 51%, and renal dysfunction in 53%. A total of 911 patients with ≥180 days of follow-up (average follow-up of 25.8 months) were included. A total of 8407 episodes from 358 patients were classified by the AI model as true AF. The incidence of AF as a function of episode duration, clinical history of AF and reduced vs preserved LVEF are shown in Figures A, B, and C respectively. Incidence of AF, as detected by an ICM over 42 months of follow-up, was estimated to be 38% to 46% depending on AF episode duration. Estimated 42-month AF incidence was 23% in patients with no clinical history of AF. The 42-month AF incidence was 44% vs 47% in HF patients with reduced versus preserved LVEF.

Conclusion
Incidence of AF, as detected by an ICM over 3 years of follow-up, was estimated to be in close to half of ICM patients with history of HF events. Close to one fourth of the patients with no prior clinical history of AF had newly detected AF. AF incidence was similar in HF patients with preserved versus reduced LVEF in this real-world cohort.