Association Between Complete Right Bundle Branch Block and Vascular Endothelial Function

BACKGROUND: Complete right bundle branch block (CRBBB) is a common electrocardiographic finding even in healthy people and generally has a good prognosis. However, recent studies have shown that CRBBB is related to arteriosclerosis and cardiovascular risk. OBJECTIVES: This study aimed to assess the association between CRBBB and vascular function. METHODS: This study included a total of 2,313 individuals. After applying the exclusion criteria, 1,308 individuals were included in the final analysis. We evaluated the endothelial function assessed by flow-mediated vasodilation and vascular smooth muscle function assessed by nitroglycerine-induced vasodilation in 55 individuals with CRBBB (34 men; mean age: 62.6 ± 16.6 years) and 1,253 individuals with normal QRS duration (527 men; mean age: 66.6 ± 14.0 years). RESULTS: Flow-mediated vasodilation was significantly lower in patients with CRBBB than that in those with normal QRS duration (3.2% [1.6%-4.7%] vs 4.6% [2.6%-6.7%]; P < 0.001). In the multivariable analysis, CRBBB was significantly associated with endothelial dysfunction (OR: 1.84; 95% CI: 1.01-3.36; P = 0.047). Although nitroglycerine-induced vasodilation was significantly lower in individuals with CRBBB than in those with normal QRS duration (11.5% [7.9%-14.9%] vs 13.1% [9.6%-17.3%] P = 0.024), no significant association was observed between CRBBB and vascular smooth muscle dysfunction based on the multivariable analysis (OR: 1.09; 95% CI: 0.53-2.22; P = 0.816). CONCLUSIONS: CRBBB was shown to be associated with endothelial dysfunction. These findings suggest that CRBBB should not be regarded as a benign electrocardiography finding from a vascular function standpoint (A study of clinical usefulness of vascular function; UMIN000039512).