Association of Right Bundle Branch Block with Ischemic Stroke Incidence: A UK Biobank Cohort Study

Introduction: Right bundle branch block (RBBB) is often considered benign; however, its association with ischemic stroke (IS) remains unclear. We aimed to investigate the relationship between RBBB and the incidence of IS. Methods: We conducted a retrospective cohort study using the UK Biobank database (2004–2021), which included 3,634 participants with new-onset RBBB and 3,643 matched controls. The primary outcome was the incidence of IS, while the secondary outcomes included atrial fibrillation (AF) and all-cause mortality. We applied a propensity score matching with variables such as age, sex, presence of hypertension, diabetes, dyslipidemia, and the Charlson Comorbidity Index. Subsequently, time-dependent Cox regression analyses were performed to assess the association between RBBB and the outcomes. Results: The cumulative incidence of IS was higher in the RBBB group. RBBB was independently associated with an increased risk of IS (adjusted hazard ratio [aHR], 3.57; 95% confidence interval [CI], 2.12–6.03; p < 0.001), as well as AF (aHR, 4.58; 95% CI, 3.86–5.43; p < 0.001) and all-cause mortality (aHR, 2.66; 95% CI, 2.35–3.02; p < 0.001). Conclusion: RBBB was associated with an increased risk of IS, independent of age, sex, and other comorbidities. These findings emphasize the need for careful monitoring and management of patients with RBBB to mitigate the risk of IS and other adverse outcomes. Further research is needed to elucidate the underlying mechanisms and better inform clinical management strategies for patients with RBBB.