The Relationship Between the Mutation of Cardiac Potassium-Channel and Early Repolarization and the Importance of the Arrhythmia Marker Tests in this Population

Abstract

Aim Early repolarization (ER) electrocardiographic pattern is not rare in the general population. This electrocardiographic (ECG) abnormality, which has been accepted as benign for years, has attracted attention with its association with sudden cardiac death (SCD). The association of fatal arrhythmia history and this pattern of ECG is defined as ER syndrome (ERS). Several tests can help clinicians to understand which ER patterns cause a risk for malignant arrhythmias. As in the other channelopathies, ion channel-related gene mutations have also been reported in ERS. In this study, we investigated the presence of the mutation in KCNJ8, which has been described for the first time in ERS in the groups with and without ER and which leads to an electrical functional change in the potassium (K) channel, causing an arrhythmia. In addition, we attempted to determine the risk for arrhythmia with 24-hour ECG monitoring and signal-averaged electrocardiogram (SAECG). Materials and Methods A total of 100 patients who met the ECG criteria, and 50 of whom had ER patterns underwent rhythm Holter evaluations. The presence of SAECG and late potentials (LP) were studied. KCNJ8 gene mutation was investigated with the Polymerase Chain Reaction (PCR) method. Results The majority of the patients in the ER pattern group were in ER type 1 pattern. Although not statistically significant, QTc intervals were shorter in the ER group. There were no significant ventricular arrhythmias in rhythm Holter records in both groups. Heart rate variability (HRV) was decreased by 26%, and late potentials (LP) were found in 14% of the patients in this group with SAECG. No correlation was found between the investigated KCNJ8-S422L genetic mutation and ER pattern. Conclusion At the end of the study, the investigated genetic mutation was observed in the control group, and not in the ER group. This can be explained by the fact that the majority of the patients in the ER group were asymptomatic for cardiac symptoms, and they had no family history of SCD. Furthermore, comprehensive studies with a larger population of patients at risk will shed light on the importance of arrhythmic tests and possible gene mutation.