Association Between Complete Right Bundle Branch Block and Vascular Endothelial Function

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.

This study aimed to assess the association between CRBBB and vascular function.

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).

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).

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).