Outcomes with T-wave discordance of left bundle branch block and preserved or mildly reduced ejection fraction.

Abstract

Left bundle branch block (LBBB) is associated with an increased risk of adverse outcomes for patients with heart failure. The prognosis of LBBB in patients with a preserved ejection fraction (EF) remains controversial. This study investigated the predictive value of T-wave discordance for the prognosis of patients with LBBB and preserved or mildly reduced EF. We enrolled 707 patients with complete LBBB and left ventricular (LV) EF≥40% observed using electrocardiograms (ECGs) and echocardiograms between January 2010 and December 2018. Their serial ECGs were reviewed during the follow-up period. The T-wave pattern was classified as discordant LBBB (dLBBB) or concordant LBBB (cLBBB) according to the 12-lead ECG T-wave morphology. The primary outcome was the composite of cardiovascular death or hospitalization for heart failure during a median follow-up period of 3.1years. A multivariable Cox regression analysis was used to evaluate the independent predictors of the primary outcome. Patients with dLBBB had more comorbidities, a higher heart rate, a longer QRS and QTc duration, a larger LV end-systolic volume and left atrial dimension, a lower LVEF, and a higher mitral E/A ratio and E/e', compared with those with cLBBB. Older age [hazard ratio (HR)=1.023, 95% confidence interval (CI)=1.001-1.046, P=0.023], history of heart failure (HR=2.440, 95% CI=1.524-3.905, P=0.001), chronic kidney disease (HR=1.917, 95% CI=1.182-3.110, P=0.008), larger LV end-systolic volume (HR=1.046, 95% CI=1.017-1.075, P=0.002), lower LVEF (HR=0.916, 95% CI=0.885-0.948, P=0.001), and presence of dLBBB (HR=1.63, 95% CI=1.011-2.628, P=0.032) were independent predictors of the primary outcome in patients with LBBB and LVEF≥40%. The discordant or concordant T-wave morphology of LBBB could transform from one subtype to the other in up to 23% of the study population during the follow-up period, and individuals with persistent or transformed dLBBB faced an increased risk of cardiovascular death or non-fatal heart failure hospitalization. In patients with LBBB and EF≥40%, dLBBB serves as an independent predictor of a higher risk of cardiovascular death or non-fatal heart failure hospitalization.