Complete Right Bundle Branch Block Predicts Mortality in Thai Patients with Chronic Heart Failure with Reduced Ejection Fraction
Wanwarang Wongcharoen MD*, Arintaya Phrommintikul MD*, Rungsrit Kanjanavanit MD*, Anong Amarittakomol RN**, Paleerat Topaiboon RN**, Warintorn Wiangosot RN**, Srun Kuanprasert MD*, Apichard Sukonthasarn MD*
Affiliation : * Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand ** Northern Cardiac Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
Background : Previous studies have shown that intraventricular conduction defect is associated with increased mortality in
heart failure (HF) population. However, it is conflicting whether left bundle branch block (LBBB) or right bundle branch
block (RBBB) is a better predictor for mortality.
Objective : To evaluate the relationship between patterns of bundle branch block (BBB) and all-cause mortality in Thai
patients with chronic heart failure with reduced ejection fraction (HFrEF) and to compare the prognostic values of RBBB and
LBBB in this population.
Material and Method: The authors retrospectively studied a cohort of 170 patients (age 58 + 14 years, male = 117) with
HFrEF requiring hospitalization and were followed-up in a heart failure clinic. Predictors of mortality were evaluated by Cox
proportional hazard analysis.
Results : Wide QRS complex (duration > 120 ms) was present in 26% of patients, 15% with LBBB, 11% with RBBB. During
an average follow-up of 1.8 + 1.6 years, 22 patients (13%) died. By univariate analysis, presence of chronic renal
insufficiency, chronic obstructive pulmonary disease, severe left ventricular systolic dysfunction and RBBB, but not LBBB
were associated with increased mortality. After multivariate adjustment, the presence of RBBB was the only strong predictor
of mortality in HF patients (OR 3.9, 95% CI 1.3-11.7, p < 0.05).
Conclusion : The presence of RBBB was the only independent predictor of mortality in Thai patients with HFrEF.
Keywords : Bundle branch block, Heart failure, Intraventricular conduction defect, Mortality predictor
