Outcomes with T-wave discordance of left bundle branch block and preserved or mildly reduced ejection fraction
Hui-Chun Huang1, Kuo-Liong Chien1,2, Yen-Bin Liu1
1Department of Internal Medicine, Division of Cardiology, National Taiwan University Hospital and National Taiwan University College of Medicine, National Taiwan University, No. 7 Chung-Shan South Rd, Taipei, 100, Taiwan.
Insights
T-wave discordance in patients with left bundle branch block (LBBB) and preserved ejection fraction (EF) predicts adverse cardiovascular events. This finding aids in risk stratification for heart failure patients with LBBB.
Area of Science:
- Cardiology
- Electrocardiography
- Heart Failure Research
Background:
- Left bundle branch block (LBBB) is linked to poor outcomes in heart failure patients.
- The prognostic significance of LBBB in patients with preserved ejection fraction (EF) is not well-established.
- T-wave discordance is a potential marker for risk stratification in LBBB.
Purpose of the Study:
- To evaluate the predictive value of T-wave discordance for prognosis in patients with LBBB and preserved or mildly reduced EF.
- To determine if T-wave morphology (discordant vs. concordant) impacts cardiovascular outcomes.
- To identify independent predictors of adverse events in this patient population.
Main Methods:
- Analysis of 707 patients with LBBB and LVEF ≥ 40% from 2010-2018.
- Classification of T-wave patterns as discordant LBBB (dLBBB) or concordant LBBB (cLBBB) on serial ECGs.
- Multivariable Cox regression to identify predictors of composite cardiovascular death or heart failure hospitalization.
Main Results:
- Patients with dLBBB exhibited more comorbidities and worse LV remodeling compared to cLBBB.
- Independent predictors of adverse outcomes included older age, heart failure history, CKD, larger LV end-systolic volume, lower LVEF, and dLBBB.
- dLBBB was associated with a 1.63-fold increased risk of cardiovascular death or heart failure hospitalization (HR=1.63, P=0.032).
Conclusions:
- T-wave discordance in LBBB is an independent predictor of adverse cardiovascular outcomes in patients with preserved EF.
- dLBBB identifies patients at higher risk for cardiovascular death or heart failure hospitalization.
- ECG T-wave morphology provides valuable prognostic information in LBBB patients with preserved EF.
Aims:
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.
Methods And Results:
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 3.1 years. 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.
Conclusions:
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.
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