Lamin A/C Missense Mutation R216C Pinpoints Overlapping Features Between Brugada Syndrome and Laminopathies

Cardiac conduction disorders in young adults: Clinical characteristics and genetic background of an underestimated population

BACKGROUND

Cardiac conduction disorder (CCD) in patients <50 years old is a rare and mostly unknown condition.

OBJECTIVE

We aimed to assess clinical characteristics and genetic background of patients <50 years old with CCD of unknown origin.

METHODS

We retrospectively reviewed a consecutive series of patients with a diagnosis of CCD before the age of 50 years referred to our center between January 2019 and December 2021. Patients underwent complete clinical examination and genetic evaluation.

RESULTS

We enrolled 39 patients with a median age of 40 years (28-47 years) at the onset of symptoms. A cardiac implantable electronic device was implanted in 69% of the patients. In 15 of 39 CCD index patients (38%), we found a total of 13 different gene variations (3 pathogenic, 6 likely pathogenic, and 4 variants of uncertain significance), mostly in 3 genes (SCN5A, TRPM4, and LMNA). In our cohort, genetic testing led to the decision to implant an implantable cardioverter-defibrillator in 2 patients for the increased risk of sudden cardiac death.

CONCLUSION

Patients with the occurrence of CCD before the age of 50 years present with a high rate of pathologic gene variations, mostly in 3 genes (SCN5A, TRPM4, and LMNA). The presence of pathogenic variations may add information about the prognosis and lead to an individualized therapeutic approach.

Brugada Syndrome: More than a Monogenic Channelopathy

Brugada syndrome (BrS) is an inherited cardiac channelopathy first diagnosed in 1992 but still considered a challenging disease in terms of diagnosis, arrhythmia risk prediction, pathophysiology and management. Despite about 20% of individuals carrying pathogenic variants in the SCN5A gene, the identification of a polygenic origin for BrS and the potential role of common genetic variants provide the basis for applying polygenic risk scores for individual risk prediction. The pathophysiological mechanisms are still unclear, and the initial thinking of this syndrome as a primary electrical disease is evolving towards a partly structural disease. This review focuses on the main scientific advancements in the identification of biomarkers for diagnosis, risk stratification, pathophysiology and therapy of BrS. A comprehensive model that integrates clinical and genetic factors, comorbidities, age and gender, and perhaps environmental influences may provide the opportunity to enhance patients' quality of life and improve the therapeutic approach.

Subepicardial Cardiomyopathy: A Disease Underlying J-Wave Syndromes and Idiopathic Ventricular Fibrillation

Brugada syndrome (BrS), early repolarization syndrome (ERS), and idiopathic ventricular fibrillation (iVF) have long been considered primary electrical disorders associated with malignant ventricular arrhythmia and sudden cardiac death. However, recent studies have revealed the presence of subtle microstructural abnormalities of the extracellular matrix in some cases of BrS, ERS, and iVF, particularly within right ventricular subepicardial myocardium. Substrate-based ablation within this region has been shown to ameliorate the electrocardiographic phenotype and to reduce arrhythmia frequency in BrS. Patients with ERS and iVF may also exhibit low-voltage and fractionated electrograms in the ventricular subepicardial myocardium, which can be treated with ablation. A significant proportion of patients with BrS and ERS, as well as some iVF survivors, harbor pathogenic variants in the voltage-gated sodium channel gene, SCN5A, but the majority of genetic susceptibility of these disorders is likely to be polygenic. Here, we postulate that BrS, ERS, and iVF may form part of a spectrum of subtle subepicardial cardiomyopathy. We propose that impaired sodium current, along with genetic and environmental susceptibility, precipitates a reduction in epicardial conduction reserve, facilitating current-to-load mismatch at sites of structural discontinuity, giving rise to electrocardiographic changes and the arrhythmogenic substrate.

Case report: Lamin A/C gene mutation in patient with drug-induced type 1 Brugada syndrome at high arrhythmic risk

We report the case of drug-induced type 1 Brugada syndrome at high arrhythmic risk associated with Lamin A/C gene mutation.

Long-Term Prognosis of Febrile Individuals with Right Precordial Coved-Type ST-Segment Elevation Brugada Pattern: A 10-Year Prospective Follow-Up Study

A febrile state may provoke a Brugada electrocardiogram (ECG) pattern and trigger ventricular tachyarrhythmias in susceptible individuals. However, the prognostic value of fever-induced Brugada ECG pattern remains unclear. We analyzed the clinical and extended long-term follow-up data of consecutive febrile patients with a type 1 Brugada ECG presented to the emergency department. A total of 21 individuals (18 males; mean age, 43.7 ± 18.6 years at diagnosis) were divided into symptomatic (resuscitated cardiac arrest in one, syncope in two) and asymptomatic (18, 86%) groups. Sustained polymorphic ventricular tachycardias were inducible in two patients with previous syncope. All 18 asymptomatic patients had no spontaneous type 1 Brugada ECG recorded at second intercostal space and no family history of sudden death. Among asymptomatic individuals, 4 had a total 12 of repeated non-arrhythmogenic febrile episodes all with recurrent type 1 Brugada ECGs, and none had a ventricular arrhythmic event during 116 ± 19 months of follow-up. In the symptomatic group, two had defibrillator shocks for a new arrhythmic event at 31- and 49 months follow-up, respectively, and one without defibrillator therapy died suddenly at 8 months follow-up. A previous history of aborted sudden death or syncope was significantly associated with adverse outcomes in symptomatic compared with asymptomatic individuals (log-rank p < 0.0001). In conclusion, clinical presentation or history of syncope is the most important parameter in the risk stratification of febrile patients with type 1 Brugada ECG. Asymptomatic individuals with a negative family history of sudden death and without spontaneous type 1 Brugada ECG, have an exceptionally low future risk of arrhythmic events. Careful follow-up with timely and aggressive control of fever is an appropriate management option.

Standard ECG in Brugada Syndrome as a Marker of Prognosis: From Risk Stratification to Pathophysiological Insights

Background

The 12‐lead ECG plays a key role in the diagnosis of Brugada syndrome (BrS). Since the spontaneous type 1 ECG pattern was first described, several other ECG signs have been linked to arrhythmic risk, but results are conflicting.

Methods and Results

We performed a systematic review to clarify the associations of these specific ECG signs with the risk of syncope, sudden death, or equivalents in patients with BrS. The literature search identified 29 eligible articles comprising overall 5731 patients. The ECG findings associated with an incremental risk of syncope, sudden death, or equivalents (hazard ratio ranging from 1.1–39) were the following: localization of type 1 Brugada pattern (in V2 and peripheral leads), first‐degree atrioventricular block, atrial fibrillation, fragmented QRS, QRS duration >120 ms, R wave in lead aVR, S wave in L1 (≥40 ms, amplitude ≥0.1 mV, area ≥1 mm²), early repolarization pattern in inferolateral leads, ST‐segment depression, T‐wave alternans, dispersion of repolarization, and Tzou criteria.

Conclusions

At least 12 features of standard ECG are associated with a higher risk of sudden death in BrS. A multiparametric risk assessment approach based on ECG parameters associated with clinical and genetic findings could help improve current risk stratification scores of patients with BrS and warrants further investigation.

Registration

URL: https://www.crd.york.ac.uk/prospero/. Unique identifier: CRD42019123794.