Electromechanical delay by speckle-tracking echocardiography: a novel tool for distinguishing between Brugada syndrome and isolated right bundle branch block

Abstract

Abstract Background The electrocardiographic (ECG) definition of Brugada syndrome (BS) can be challenging because benign ECG abnormalities, such as right bundle branch block (RBBB), may mimic pathological ECG characteristics of BrS. However, although myocardial delay and deformation can be quantified by advanced imaging, it has not yet been used to differentiate between BrS and RBBB. Purpose The aim of this study was to characterize the electro-mechanical behavior of the heart of patients with type-1 BrS and subjects with isolated complete RBBB in order to differentiate these conditions. Methods In this two-center study, 66 subjects were analyzed by standard and speckle-tracking echocardiography (STE): 22 type-1 BrS, 24 isolated complete RBBB, and 20 healthy subjects. The participants were not treated by any drug potentially influencing myocardial conduction. Results Standard echocardiographic parameters did not differ among the groups. STE demonstrated that right ventricular (RV) mechanical dispersion (MD) was greater in RBBB as compared to BrS and controls (p<0.05). In patients with isolated RBBB, the greatest delay of RV time-to-peak longitudinal strain (TTP) was found in RV free-wall basal segments. Mean absolute deviations of TTP calculated for each left ventricular (LV) region were greater in patients with RBBB as compared to those with BrS and to controls with a localisation of the delay in LV antero-septal, anterior, lateral, and infero-septal basal segments (figure 1). Conclusions Advanced echocardiographic techniques may help to differentiate between BrS and RBBB. Indeed, STE allows to identify an electro-mechanical conduction delay in RBBB patients that is not found in patients affected by type-1 BrS. Electromechanical delay by STE Funding Acknowledgement Type of funding source: Public Institution(s). Main funding source(s): Italian Society of Cardiology