The role of ILR monitoring in patients with a family history of SADS, a view from real clinical practice
Authors: Durand R , Balfe C , Jain D , McKearney E , Ward D , Crinion D 
Published: October 2021

Abstract

Background/Introduction
Implantable Loop Recorder (ILR) device monitoring is an established method for long term heart rhythm monitoring in patients with inherited cardiac conditions. Many present with a family history of Sudden Arrhythmic Death Syndrome (SADS). The value of ILR findings in the investigation of SADS relatives has not been well documented.

Purpose
We aimed to evaluate the impact of ILR monitoring on the management plans of patients with a family history of SADS.

Methods
We performed a retrospective analysis of the ILR reports and electronic patient records of all patients at the inherited cardiac disease clinic with a family history of SADS and an ILR implanted. Patient demographics, ILR implant indication and specific changes to management plans were recorded and analysed using descriptive statistics.

Results
All 135 patients with ILR monitoring at the inherited cardiac disease clinic were screened and 87 patients (57.6% female, 41.7±14.0 years) with SADS relatives were included in the study. The mean follow up period was 657.9±392.3 days from ILR implant. Indications for ILR implantation included syncope (n=31, 15.7%), presyncope (45, 22.7%), palpitations (44, 22.2%), chest pain (9, 4.5%), short term heart rhythm monitor findings (6, 3.0%), ECG findings (6, 3.0%), asymptomatic indications (10, (5.1%) including patients with more than one relative with SADS, a family history of conduction disease or family history of long QT syndrome), and atypical symptoms (2 (1%) including seizures and sleep paralysis). Some patients had more than one indication for ILR at the time of implant. As a direct result of ILR monitoring, 43 (49.4%) patients had a change to their management plan. 6 specific definitions for management changes were used: Permanent pacemaker implantation (2, 2.3%), subsequent electrophysiology study (3, 3.5%), medication change (7, 8.1%), arrhythmia excluded as a cause for patient symptoms (26, 29.9%), prompted ILR implant in first degree relative (11, 12.6%) and ILR re-implant for further monitoring for premature conduction disease (1, 1.2%). Patients whose indication for ILR implant was palpitations had the highest likelihood for change of management with 27 changes associated with this indication, of which exclusion of arrhythmia as a cause for symptoms (15) was the most frequent outcome. The indications, syncope and presyncope both yield 21 management changes each.

Conclusion
The use of ILR devices in family relatives of patients with SADS provides information that may directly impact on patient management, with syncope providing the highest yield and reassurance the most common outcome in our cohort. ILR monitoring helped guide a wide range of other management strategies which included changes to medications and the need for further cardiac procedures. This data represented clinical practice in a niche patient cohort who are at risk for inherited cardiac conditions and associated arrhythmias.

Funding Acknowledgement
Type of funding sources: None. Indication for ILR vs management changeIndications for ILR implant