Right bundle branch block and risk of cardiovascular mortality: the Ibaraki Prefectural Health Study

Area of Science:

• Cardiology
• Public Health
• Epidemiology

Background:

• Historically, right bundle branch block (RBBB) was considered benign in asymptomatic individuals, based on limited older research.
• Recent evidence suggests a potential underestimation of RBBB's cardiovascular implications.
• The association between complete right bundle branch block (CRBBB) and cardiovascular outcomes requires further large-scale investigation.

Purpose of the Study:

• To investigate the association between CRBBB and subsequent cardiovascular mortality in a large Japanese general population cohort.
• To identify specific demographic groups at higher risk associated with CRBBB.
• To inform clinical awareness regarding CRBBB in seemingly healthy individuals.

Main Methods:

• A large community-based cohort study involving 90,022 individuals in Japan, with data assessed from annual health check-ups.
• Longitudinal follow-up from 1993 to the end of 2016.
• Statistical analysis using Cox proportional hazards models and log-rank tests to determine the association between CRBBB and cardiovascular mortality.

Main Results:

• CRBBB was identified in 1.5% (1,344 participants) of the study cohort.
• CRBBB was significantly associated with an increased risk of cardiovascular mortality (HR 1.21; 95% CI 1.06-1.38) after adjusting for confounders.
• The risk was particularly elevated in women under 65 years (HR 2.00) and men 65 years and older (HR 1.28).

Conclusions:

• CRBBB is associated with an increased risk of cardiovascular mortality, challenging the historical view of it being benign.
• Specific subgroups, namely pre-menopausal women and elderly men, face a disproportionately higher risk.
• Clinicians should consider CRBBB a potential risk factor for cardiovascular mortality, even in asymptomatic patients, particularly within these identified demographic groups.