Background: Interest in bundle-branch block has focused primarily on its role as a predictor of mortality and coexisting cardiovascular diseases. Previous studies of prevalence, correlation to cardiovascular disease, and mortality have produced conflicting results.
Methods and results: We studied a random-sampled population of 855 men who were 50 years old in 1963 and followed them up for 30 years with repeated examinations. Men who developed bundle-branch block were studied with regard to cumulative incidence, relationship with cardiovascular disease/risk factors, and survival. The prevalence of bundle-branch block increases from 1% at age 50 years to 17% at age 80 years, resulting in a cumulative incidence of 18%. No significant relationship with ischemic heart disease or mortality was found. Men who would develop bundle-branch block had a bigger heart volume at age 50 years and developed diabetes mellitus and congestive heart disease during follow-up more often than control subjects.
Conclusions: Bundle-branch block correlates strongly to age and is common in elderly men. Our results support the theory that bundle-branch block is a marker of a slowly progressing degenerative disease that also affects the myocardium.