Temporal Changes in Left Ventricular Strain in Typical and Atypical Left Bundle Branch Block Patients: A Follow-up Study.

Abstract

Left bundle branch block (LBBB) is a conduction abnormality that alters the pattern of left ventricular (LV) activation and contraction, leading to ventricular remodeling, typically manifesting as LV hypertrophy and dilatation. This remodeling is often associated with progressive cardiac dysfunction and a poor prognosis. To compare temporal changes in left ventricular strain patterns in patients with typical and atypical LBBB over a period of two years. Electrocardiographic, echocardiographic, and strain parameters were obtained at two-year follow-up from previously enrolled patients. Of the 181 patients initially enrolled, 152 were contacted telephonically. Among them, 23 patients underwent follow-up evaluation, 4 patients received cardiac resynchronization therapy (CRT), and 21 deaths were recorded. Significant changes between baseline and follow-up were observed in left ventricular end-diastolic dimension (LVEDD), left ventricular filling time (LVFT), LVFT/R-R interval, three-dimensional systolic dyssynchrony index (SDI), and left ventricular ejection fraction (EF). Compared with survivors, non-survivors had significantly lower baseline EF, and global longitudinal strain (GLS). An ALEF ≤40% was identified as a significant predictor of mortality. Multivariable regression analysis demonstrated that ALEF, GLS, and age were independent predictors of mortality. The all-cause mortality rate over two years among patients with LBBB was 13.8%. Age, ALEF, and GLS were significant predictors of mortality. Improvements in left ventricular function and ventricular dyssynchrony were observed during follow-up; however, the factors contributing to these changes could not be determined from the present study. Clinical Trials Registry-India on 02/05/2023 under the reference number CTRI/2023/05/052206.