Implantable loop recorders in Brugada syndrome: symptoms and arrhythmia characterization

This commentary refers to ‘Implantable loop recorders in patients with Brugada Syndrome: the BruLoop study’, by M. Bergonti et al., https://doi.org/10.1093/eurheartj/ehae133 and the discussion piece ‘Implantable loop recorders in patients with Brugada syndrome: the importance of a correct patient stratification’, by G. Dendramis, https://doi.org/10.1093/eurheartj/ehae393. We appreciate the opportunity to discuss details and implications of the BruLoop study.1 Our study predominantly involved low- to intermediate-risk patients with Brugada syndrome (BrS), as high-risk patients and secondary prevention patients are usually treated with an implantable cardioverter-defibrillator (ICD) implantation. The focus of our research was not to assess the utility of implantable loop recorders (ILRs) to stratify the risk of ventricular arrhythmias but to better characterize non-ventricular arrhythmias (atrial and bradyarrhythmias) and to properly investigate the aetiology of unexplained syncope. The specific rate of spontaneous Type 1 electrocardiogram (40.5%) and the characteristics of the population are reported in our manuscript. Predictors of overall arrhythmias and ventricular arrhythmias are detailed in the Results section. Moreover, the author of the commentary states ‘arrhythmic events during follow-up are significantly associated with a history of atrial arrhythmias and conduction abnormalities’. Yet, no reference for this statement is provided. Higher prevalence of atrial arrhythmias and occurrence of bradyarrhythmias has been described in high-risk BrS patients in small descriptive studies.2,3 To the best of our knowledge, no systematic assessment of the prognostic value of atrial arrhythmia and bradyarrhythmias in patients with BrS has been carried out so far. Therefore, no conclusive statement on their prognostic value can be provided, and we would like to remark that our study did not address the prognostic value of atrial and bradyarrhythmias detected by ILR. Further studies are needed to clarify whether such association is present. We agree that current guideline-based indications on ILR implantation for BrS patients with unexplained syncope are based on small sample size and single-centre studies. Therefore, our study strengthens, with a large population of patients, the current evidence by demonstrating how ILRs can offer actionable data in a specific subset of BrS patients over a 3-year median follow-up. Although this period may be considered short, it provides critical insights into arrhythmic patterns and improved management strategies for these patients, possibly avoiding unnecessary ICD implantations in patients with arrhythmic syncope of non-ventricular origin. All authors declare no disclosure of interest for this contribution. This study was supported by a research grant of the Swiss National Science Foundation (SNSF), PZ00P3_180055.