Right ventricular function and dyssynchrony in Brugada syndrome: Highlighting the importance of the mechanical substrate in the right ventricular outflow tract

Abstract

Background: Current evidence suggests that Brugada syndrome (BrS), far from being a purely electrical condition, is associated with subtle mechanical abnormalities primarily affecting the right ventricle (RV). We aimed to characterize RV function in BrS and investigate the echocardiographic profile of patients with arrhythmic events, with a special focus on parameters of RV dyssynchrony using speckle-tracking echocardiography (STE).

Methods: An echocardiogram was performed in 71 BrS patients and 25 healthy controls. STE was performed to assess regional and global RV mechanics, including RV outflow tract shortening (RVOTS). RVOT contraction time was considered to calculate the modified RV mechanical dispersion (RVMD_m). Arrhythmic events were prospectively evaluated in the BrS cohort.

Results: Compared to controls, BrS patients showed subtle contractile abnormalities, including impaired RV longitudinal strain, higher RV index of myocardial performance (RIMP) and lower RVOTS. BrS patients also exhibited a greater contraction delay between the lateral and the septal aspect of the RV. After a median follow-up of 7.3 year (IQR 5.2-10.8), 6 patients presented malignant arrhythmic events. RIMP >0.50, RVOTS <16.2% and RVMD_m > 42 ms showed high sensitivity for the identification of BrS patients with arrhythmic events during follow-up.

Conclusions: Subtle RV mechanical abnormalities were present in BrS patients. RIMP and RVOTS, a novel STE-derived parameter, were found to be sensitive markers of arrhythmic events. Adding the RVOT contraction time to the analysis of RVMD may help identify patients at higher risk, reflecting the importance of the RVOT mechanical substrate in the assessment of the arrhythmic risk in BrS.

Keywords: Brugada syndrome; Mechanical dispersion; Risk stratification; Speckle tracking echocardiography; Strain; Ventricular arrhythmia.