Abstract 13585: In Patients With Right Bundle Branch Block, ECG Z-Axis QRS-T Voltage-Time-Integral Predicts Right Ventricular Structure and Function

Abstract

Introduction: Right bundle branch block (RBBB) is the most common His-Purkinje conduction abnormality seen on ECG. It is currently unclear if there are any quantitative ECG differences in RBBB without and with structural right ventricular (RV) disease. Our aim was to evaluate quantitative ECG predictors of echocardiographic RV measurements [tricuspid annular plane systolic excursion (TAPSE), tissue Doppler imaging RV S’, RV basal and mid diameters, RV systolic pressure (RVSP)]. Hypothesis: QRS-T VTI in patients with RBBB is a marker for adverse RV remodeling and dysfunction. Methods: We included adults with ECG demonstrating typical RBBB and echocardiogram performed within 3 months of each other in 2010-2020. Orthogonal X, Y, Z ECG leads were reconstructed using Kors matrix. In addition to overall QRS duration, QRS voltages and QRS/QRS-T VTIs from 12 standard leads, X, Y, Z leads, and 3D (root-mean-square) ECG were evaluated. Age, sex and BSA-adjusted linear regressions were used to assess associations between ECG variables and RV measurements. We separately generated ROC curves for predicting abnormal RV measurements from ECG variables. Results: We included 782 patients (33% women, 71±14 years). Amongst the ECG variables, BSA-indexed Z-axis QRS-T VTI (VTI QRST-Z *√BSA) was the strongest independent predictor of all 5 RV measurements (Table 1a shows a comparison of QRS duration, Z-axis amplitude and VTI). VTI QRST-Z *√BSA cutoff 62 μVsm had a sensitivity 62.7% and specificity 65.7% to distinguish presence of ≥3 abnormal out of the 5 RV measurements (Table 1b). Conclusions: Adverse RV remodeling causes augmentation of the anterior-posteriorly directed QRS-T potential which is seen as a change in Z-axis VTI. VTI QRST-Z *√BSA could be used as a marker for right heart failure in patients with RBBB.