Novel approaches using electrocardiographic imaging for early detection of ARVC in patients and relatives and symptoms preceding sudden death

Abstract: Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) is an inherited disease of the myocardium, predominantly affecting the right ventricle (RV). Arrhythmias are common among patients with the disease and Sudden Cardiac Death (SCD) can occur even in early stages. The overall purpose of this thesis was to investigate the effectiveness of new diagnostic methods in detecting early abnormalities in genetically predisposed individuals and to emphasize the importance of early diagnosis. The analysis of body surface mapping (BSM) signals recorded using a 252-lead vest revealed abnormal repolarisation patterns in all ARVC patients, but also in 25% of family members who were carriers of the family pathogenic variant (M-carriers). The abnormal repolarization patterns preceded repolarization abnormalities on 12-leads electrocardiogram (ECG). Depolarization abnormalities were also detected by the analysis of body surface signals. The QRS dispersion calculated by the body surface signals was significantly higher among ARVC patients compared with controls. 20% of M-carriers presented also with a slightly elevated QRS dispersion. ECG based QRS dispersion could not adequately differentiate ARVC patients from controls. Thus, the higher resolution of the BSM system permitted the detection of repolarization and depolarization abnormalities even in early stages of the disease.The analysis of reconstructed epicardial signals using Electrocardiographic Imaging (ECGI) revealed terminal ventricular epicardial activation (the last 20msecs) located only in parts of RV, as opposed to controls, where the right ventricular outflow tract (RVOT) and cardiac base (both right and left ventricle) were activated last. The total ventricular activation time and the RV activation time were both longer in ARVC patients, whereas the area activated during the last 20 msecs was smaller. Similar pattern with delayed conduction in limited areas of the RV were also observed in 50% of the M-carriers. This subgroup presented also smaller area of terminal ventricular activation and longer RV activation time, but the total ventricular activation was normal. Through nationwide registries, the first SCD cohort due to ARVC in Sweden was described. Cardiac related symptoms were common (68%) prior to death and 36% of cases had sought medical care the last six months prior to death. A family history of SCD was present in 45% of the cases.  The careful clinical evaluation of young individuals seeking with cardiac related symptoms and the evaluation of both medical and family history is crucial.In conclusion, new technologies, using multiple electrodes for the recording of body surface signals and the reconstruction of the epicardial signals have shown promising results in detecting early repolarization and depolarization abnormalities and could facilitate the early diagnosis in M-carriers.