Elsevier

Heart Rhythm

Volume 19, Issue 1, January 2022, Pages 70-78
Heart Rhythm

Clinical
Sudden Death
Role of subcutaneous implantable loop recorder for the diagnosis of arrhythmias in Brugada syndrome: A United Kingdom single-center experience

https://doi.org/10.1016/j.hrthm.2021.08.034Get rights and content

Background

Experience with implantable loop recorders (ILRs) in Brugada syndrome (BrS) is limited.

Objective

The purpose of this study was to evaluate the indications and yield of ILR monitoring in a single-center BrS registry.

Methods

Demographic, clinical and follow-up data of BrS patients with ILR were collected.

Results

Of 415 BrS patients recruited consecutively, 50 (12%) received an ILR (58% male). Mean age at ILR implantation was 44 ± 15 years. Thirty-one (62%) had experienced syncopal or presyncopal episodes, and 23 (46%) had palpitations. During median follow-up of 28 months (range 1–68), actionable events were detected in 11 subjects (22%); 7 had recurrences of syncope/presyncope, with 4 showing defects in sinus node function or atrioventricular conduction. New supraventricular tachyarrhythmias were recorded in 6 subjects; a run of fast nonsustained ventricular tachycardia was detected in 1 patient. Patients implanted with an ILR were less likely to show a spontaneous type 1 pattern or depolarization electrocardiographic (ECG) abnormalities compared to those receiving a primary prevention implantable-cardioverter defibrillator. Age at implantation, gender, Shanghai score, and ECG parameters did not differ between subjects with and those without actionable events. ILR-related complications occurred in 3 cases (6%).

Conclusion

In a large cohort of BrS patients, continuous ILR monitoring yielded a diagnosis of tachy- or bradyarrhythmic episodes in 22% of cases. Recurrences of syncope were associated with bradyarrhythmic events. Use of ILR can be helpful in guiding the management of low-/intermediate-risk BrS patients and ascertaining the cause of unexplained syncope.

Introduction

Brugada syndrome (BrS) is characterized by “coved” ST segment elevation ≥2 mm in the right precordial electrocardiographic (ECG) leads (type 1 pattern) and increased risk of ventricular arrhythmias (VAs) and sudden cardiac death (SCD).1,2 The incidence of life-threatening VAs in previously asymptomatic subjects with BrS is estimated at 0.3% to 1% per year.3,4 The only proven strategy for prevention of SCD is the implantable-cardioverter defibrillator (ICD), which is recommended in patients with previous aborted cardiac arrest/documented VAs and can be useful in patients with previous arrhythmic syncope and a spontaneous type 1 pattern.1,2 Several other clinical, ECG, and invasive risk factors have been proposed in subjects without documented VAs,5 but risk stratification remains challenging. Subjects with BrS often suffer from neurocardiogenic or unexplained syncopal episodes as well as palpitations secondary to paroxysmal atrial arrhythmias (atrial fibrillation [AF], atrial tachycardia [AT], or atrioventricular nodal reentrant tachycardia [AVNRT]). These have not been associated consistently with VAs during follow-up.6, 7, 8, 9, 10

Implantable loop recorders (ILRs) are indicated for investigation of syncope or palpitations in high-risk patients in whom comprehensive evaluation has not demonstrated a cause or led to treatment.11 ILRs may have a role in correlating symptoms and suspected VA in BrS patients,2,12 preventing unnecessary ICD implantation, and offering reassurance. However, the experience with ILRs in BrS is limited.8,13,14 This study sought to evaluate the indications for ILR implantation and the yield of ILR-guided diagnosis in a large single-center cohort of BrS patients.

Section snippets

Study population

Consecutive adult patients with a diagnosis of BrS were included from 2008 to June 2020. Subjects with significant coronary or cardiomyopathic disease or metabolic abnormality at the time of type 1 ECG pattern were excluded. The study was approved by the regional ethics committee and Trust R&D. All patients provided informed consent for inclusion in the study.

Data collection

Retrospective demographic and clinical data, including symptoms, results of cardiac investigations and genetic tests, and details on

Clinical population

Four hundred fifteen subjects were included in the study. All subjects underwent investigations to exclude BrS phenocopies.17 A total of 50 patients (12%) received an ILR. Twenty-nine (58%) were male, and 33 were Caucasian (66%). Twenty-nine subjects (58%) had a probable/definite diagnosis of BrS based on the Shanghai score. Mean age at ILR implantation was 44 ± 15 years. Thirty-one subjects (62%) previously had experienced a syncopal or presyncopal episode. In 18 subjects the syncope was

Comparison between subjects receiving ILR, ICD,or no device therapy

We compared the demographic, clinical, ECG, and genetic characteristics of subjects without previous aborted cardiac arrest who received an ILR, an ICD, or no device (Table 1). Those who received an ICD for primary prevention were more likely to display a spontaneous type 1 pattern compared to those receiving an ILR, whereas there were no differences with regard to gender, age at implantation, Shanghai score, genetic background, or inducibility of VF at EPS between the 2 groups. Subjects who

Discussion

To our knowledge, the present study details the largest experience with the use of ILRs in patients with BrS reported to date. The main finding is that ILR monitoring detected an actionable arrhythmia in 22% of subjects considered to be at insufficient risk for life-threatening VAs to warrant immediate ICD implantation. Diagnoses were made in 4 of 7 of subjects who suffered a recurrence of syncope or presyncope and in 5 of 10 subjects with symptomatic palpitations. Paroxysmal sinus node or AV

Conclusion

Implantable cardiac monitor devices are useful to guide diagnosis in symptomatic BrS subjects deemed at insufficient risk for SCD to require immediate ICD implantation. Recurrent syncope, including unexplained episodes in subjects without spontaneous type 1 pattern and with negative EPS, often is secondary to conduction and sinus nodal dysfunction.

Acknowledgment

The authors thank Miss Katie Frampton for her support in the realization of this work.

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    Funding Sources: Dr Scrocco is supported by the Robert Lancaster Memorial Fund sponsored by McColl’s Retail Group Ltd and by the British Heart Foundation (BHF Project Grant PG/15/107/31908). Disclosures: The authors have no conflicts of interest to disclose.

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