Abstract 258: Mortality Comparison of Right Bundle Branch Block and Left Bundle Branch Block in US Veterans Undergoing Left Heart Catheterization – A Long Term Follow-up Study

Background: The prognostic importance of right bundle branch block (RBBB) has been debated. It has been described as a benign variant, especially when compared to left bundle branch block (LBBB). We studied the presence of bundle branch blocks in a high-risk U.S. Veteran cohort.

Methods: Retrospective electrocardiogram (ECG) analysis for presence of RBBB or LBBB was conducted in 1,535 consecutive patients presenting for left heart catheterization. Evaluated risk factors were gender, age, BMI, hypertension, hyperlipidemia, diabetes, smoking history, chronic kidney disease, reduced ejection fraction and history of previous revascularization. Mean follow up time was 112 ± 66 months.

Results: Analysis of 1,535 ECGs revealed 113 patients with RBBB and 65 patients with LBBB. Risk factor burden between the two groups appeared similar with exception of higher incidence of reduced ejection fraction and previous revascularization in the LBBB group. Mortality of RBBB group was 92.0% compared to 96.9% of LBBB group. Mean time to death for RBBB group was 74.1 months compared to 61.0 months for LBBB group. Hazard ratio (HR) for RBBB with Cox regression controlling for aforementioned risk factors was 1.41, 95% CI = 1.14-1.74; p =.002. HR for LBBB controlling for the same risk factors was 1.84, 95% CI = 1.42-2.40; p =<.001.

Conclusion: In a high-risk cohort of US Veterans, both LBBB and RBBB are independent risk factors for mortality. While LBBB is a known adverse risk factor, presence of RBBB portends a poor prognosis and warrants further research.