Early repolarization syndrome: A case report focusing on dynamic electrocardiographic changes before ventricular arrhythmias and genetic analysis

Early repolarization: Electrocardiographic cues to distinguish benign from malignant variants

Historically, early repolarization (ER) has been considered a marker of good health as it is more prevalent in athletes, younger persons, and at slower heart rates. However, contemporary reports, largely based on data from resuscitated sudden cardiac arrest patients, suggest an association between ER and an increased risk for sudden cardiac death and the development of malignant ventricular arrhythmias. Therefore, after we present a brief-case presentation, we intend to review a challenging topic in recognition of malignant variants and propose a four-step comprehensive approach to simplify ECG discrimination when assessing ER changes.

Electrocardiographic features in SCN5A mutation-positive patients with Brugada and early repolarization syndromes: a systematic review and meta-analysis

Background

Early repolarization syndrome (ERS) and Brugada syndrome (BrS) are both J-wave syndromes. Both can involve mutations in the SCN5A gene but may exhibit distinct electrocardiographic (ECG) differences. The aim of this systematic review and meta-analysis is to investigate possible differences in ECG markers between SCN5A-positive patients with ERS and BrS.

Methods

PubMed and Embase were searched from their inception to 20 October 2021 for human studies containing the search terms “SCN5A” and “variant” and “early repolarization” or “Brugada”, with no language restrictions. Continuous variables were expressed as mean±standard deviation. PR interval, QRS duration, QTc and heart rate from the included studies were pooled to calculate a mean for each variable amongst BrS and ERS patients. A two-tailed Student’s t test was then performed to for comparisons.

Results

A total of 328 studies were identified. After full-text screening, 12 studies met our inclusion criteria and were included in this present study. One hundred and four ERS patients (mean age 30.86±14.45) and 2000 BrS patients (mean age 36.17±11.39) were studied. Our meta-analysis found that ERS patients had shorter QRS duration (90.40±9.97 vs. 114.79±20.10, P = 0.0001) and shorter corrected QT intervals (QTc) with borderline significance (393.63±40.04 vs. 416.82±37.43, P = 0.052). By contrast, no significant differences in baseline heart rate (65.15±18.78 vs. 76.06±18.78, P = 0.068) or PR intervals (197.40±34.69 vs. 191.88±35.08, P = 0.621) were observed between ERS and BrS patients.

Conclusion

BrS patients with positive SCN5A mutations exhibited prolonged QRS, indicating conduction abnormalities, whereas ERS patients with positive SCN5A mutations showed normal QRS. By contrast, whilst QTc intervals were longer in BrS than in ERS SCN5A positive patients, they were within normal limits. Further studies are needed to examine the implications of these findings for arrhythmic risk stratification.

AKAP9-Related Channelopathy: Novel Pathogenic Variant and Review of the Literature

Disease-associated pathogenic variants in the A-Kinase Anchor Protein 9 (AKAP9) (MIM *604001) have been recently identified in patients with autosomal dominant long QT syndrome 11 (MIM #611820), lethal arrhythmia (ventricular fibrillation, polymorphic ventricular tachycardia), Brugada syndrome, and sudden unexpected death. However, AKAP9 sequence variations were rarely reported and AKAP9 was classified as a "disputed evidence" gene to support disease causation due to the insufficient genetic evidence and a limited number of reported AKAP9-mutated patients. Here, we describe a 47-year-old male carrying a novel frameshift AKAP9 pathogenic variant who presented recurrent syncopal attacks and sudden cardiac arrest that required a semi-automatic external defibrillator implant and an electric shock treatment of ventricular arrhythmia. This study provides insight into the mechanism underlying cardiac arrest and confirms that AKAP9 loss-of-function variants predispose to serious, life-threatening ventricular arrhythmias.