Investigation of the markers of sudden cardiac death and arrhytmia, and relationship of gene mutation KCNJ8-S422l in the population with early repolarization pattern on ecg

SUMMARYIntroduction: Early repolarization (ER) is defined as the elevation of J point at least 1mm(0.1mV) in 2 consequent derivations on ECG. Early Repolarization Syndrome (ERS) which isusually seen in people without structural heart disease is considered under the title of `J wavesyndromes? because of its similarities with Brugada syndrome (BS). As a result of multicenterstudies, the association of ERS with sudden cardiac death (SCD) established and itsnow known that ERS is a cause of life threatening ventricular arrhytmias.Purpose: Aim of the study to detect the individuals at risk among the patients with ERS usingthe arrhytmia markers and investigate the existence of reported S422L mutation in the KCNJ8gene, that are detected in the patients with SCD an diagnosed ERS.Methods: Study included 50 symptomatic or asymptomatic patients with diagnosed ERS and50 people with normal ECG as the control group. People without coronary artery disease andwith normal echocardiography results are included. Mean age was 33.1±9.7 in the studygroup and 45.8±9.9 in the control group. The existence of arrhytmia, heart rate variability andlate potentials is examined in ER group. In both groups S422L mutation in the KCNJ8 gene isgenotyped using allele specific PCR.Results: In our study using the `ER ECG pattern typing? 54% of the patients with ER aredefined as type l, 42% type 2 and 4% are type 3 ER pattern. It is found that corrected QTdistance (QTc) is shorter in the ER group than in the control group, but in the level ofstatistical significance (In the ER group mean QTc; 371±28.7 ms, in the control group meanQTc; 381±31.4 ms, p =0.08). No couplet/trıplet VPC or nonsustained ventricular tachycardiais detected in the holter recordings of ERS group.Heart rate variability is found to be decreased 26% in the patients, using the time domainmethods.By using signal averaged ECG.in late potentials are detected in 14% of the patients. Thesefinding is consistent with the results of contemporary studies.History of unexplained syncope is found in 2 patients with normal neurologic assessment andthe association of syncope with ERS was not statistically significant ( p=0.15).The S422L- KCNJ8 gene mutation which is investigated in both groups, is detected in thecontrol group, but not in the study group, making the association of mutation with ERSstatistically insignificant. Neverthless, it should be stressed that no ERS patients in the studyhas sudden cardiac death in themselves and their families and only 50 patients with ER areincluded in the study.Conclusion: ERS which is included under the title of primary arrthytmogenic syndromes andchannelopaties and considered as a completely benign ECG finding, has drawn attention dueto its similarities with BS and association with SCD. We planed this study to detect thesusceptible population with arrhytmia markers,and investigate the relationship of KCNJ8-S422L mutation with ERS.It is known that the only treatment secondary prevention in ERS patients with SCDimplantable cardioverter defibrilator (ICD). The emerging problem is to detect whichindividuals with this ECG finding is susceptible to SCD, and could be protected by primaryprevention.In clinical practise, patients at risk should be detected using the criteria proposed in literature.In patients with ER pattern, history of unexplained syncope or SCD in family, >0,2mV J pointelevation in inferior/inferolateral (type 2) or all derivations (type 3), existence ofhorizontal/downslopping ST segment elevation or short QT with ER pattern, and finallydetection of couplet VPC are cosidered at risk factors.The question regarding the need of primary treatment and follow up and all patients with highrisk factors will find an answer light of future genetic investigations.