Implantable loop recorders in patients with Brugada syndrome: the BruLoop study

Abstract

Background and aims: Available data on continuous rhythm monitoring by implantable loop recorders (ILRs) in patients with Brugada syndrome (BrS) are scarce. The aim of this multi-centre study was to evaluate the diagnostic yield and clinical implication of a continuous rhythm monitoring strategy by ILRs in a large cohort of BrS patients and to assess the precise arrhythmic cause of syncopal episodes.

Methods: A total of 370 patients with BrS and ILRs (mean age 43.5 ± 15.9, 33.8% female, 74.1% symptomatic) from 18 international centers were included. Patients were followed with continuous rhythm monitoring for a median follow-up of 3 years.

Results: During follow-up, an arrhythmic event was recorded in 30.7% of symptomatic patients [18.6% atrial arrhythmias (AAs), 10.2% bradyarrhythmias (BAs), and 7.3% ventricular arrhythmias (VAs)]. In patients with recurrent syncope, the aetiology was arrhythmic in 22.4% (59.3% BAs, 25.0% VAs, and 15.6% AAs). The ILR led to drug therapy initiation in 11.4%, ablation procedure in 10.9%, implantation of a pacemaker in 2.5%, and a cardioverter-defibrillator in 8%. At multivariate analysis, the presence of symptoms [hazard ratio (HR) 2.5, P = .001] and age >50 years (HR 1.7, P = .016) were independent predictors of arrhythmic events, while inducibility of ventricular fibrillation at the electrophysiological study (HR 9.0, P < .001) was a predictor of VAs.

Conclusions: ILR detects arrhythmic events in nearly 30% of symptomatic BrS patients, leading to appropriate therapy in 70% of them. The most commonly detected arrhythmias are AAs and BAs, while VAs are detected only in 7% of cases. Symptom status can be used to guide ILR implantation.

Keywords: Atrial arrhythmias; Brady-arrhythmias; Brugada syndrome; Loop recorder; Rhythm monitoring; Sudden cardiac death; Syncope; Ventricular arrhythmias.

Structured Graphical Abstract

In our large cohort of 370 Brugada syndrome (BrS) patients from 18 international centers monitored continuously with an implantable loop recorder (ILR) for 3 years, 25.4% of the patients experienced an arrhythmic event (per-patient analysis). Specifically, 16% experienced an atrial arrhythmia, 5% a ventricular arrhythmia (VA), and 8% a bradyarrhythmia (per-event analysis). The occurrence of arrhythmic syncope in the whole cohort was 8.6% (32/370). The induction of ventricular fibrillation (VF) during an electrophysiological (EP) study emerged as the only predictor of VAs in this cohort. The clinical implications are detailed in the lower right part of the figure (SCD, sudden cardiac death; PM, pacemaker; ICD, implantable cardioverter-defibrillator; Drugs include anti-arrhythmic drugs and anticoagulants; CA, catheter ablation for atrial arrhythmias or VAs).

Figure 1

Arrhythmic event free-survival stratified according to symptom status before implantable loop recorder implant. Top panel: overall arrhythmias (atrial tachyarrhythmias, ventricular arrhythmias, and bradyarrhythmias); bottom panel: ventricular arrhythmias

Figure 2

Type of arrhythmia detected at implantable loop recorder monitoring, stratified according to symptom status at baseline

Figure 3

Characterization of syncope by implantable loop recorder. Details on the arrhythmic event are as follows: Bradyarrhythmias (n = 19, 59.3%): atrio-ventricular block (n = 4), Sinus arrest (n = 15). Atrial arrhythmias (n = 5, 15.7%): Atrial fibrillation (n = 5). Ventricular arrhythmias (n = 8, 25.0%): sustained ventricular tachycardia (n = 3), ventricular fibrillation or polymorphic ventricular tachyarrhythmias (n = 2), non-sustained ventricular tachyarrhythmias (n = 3)

Figure 4

Arrhythmia distribution in different age groups. In the bottom line, age groups divided by years of age are presented as < 30 years of age; 30–40 years of age, 40–50 years of age, 50–60 years of age, and > 60 years of age