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Natural history of isolated bundle branch block
G J Fahy1, S L Pinski, D P Miller
1Cleveland Clinic Foundation, Cleveland, Ohio, USA.
Insights
Bundle branch block (BBB) in individuals without heart disease does not increase overall mortality. However, left BBB is linked to higher cardiac mortality and a greater risk of developing cardiovascular disease.
Area of Science:
- Cardiology
- Epidemiology
- Internal Medicine
Background:
- Bundle branch block (BBB) is a common cardiac conduction abnormality.
- The long-term prognosis of BBB in individuals without clinically evident cardiovascular disease requires further elucidation.
- Prevalence of BBB increases with age.
Purpose of the Study:
- To investigate the long-term outcomes of patients with bundle branch block (BBB) and no clinical evidence of cardiovascular disease.
- To compare the outcomes of individuals with BBB to age- and sex-matched controls.
- To assess the association of left BBB and right BBB with overall mortality, cardiac mortality, and incident cardiovascular disease.
Main Methods:
- A screening program identified 310 subjects with BBB and 310 matched controls from 110,000 participants.
- Mean follow-up duration was 9.5 years.
- Outcomes analyzed included overall survival, cardiac mortality, and development of cardiovascular disease.
Main Results:
- Isolated right BBB was more prevalent than isolated left BBB (0.18% vs 0.1%).
- Total survival was similar between BBB groups and controls.
- Cardiac mortality was significantly higher in the left BBB group (p=0.01).
- Left BBB was associated with an increased prevalence of cardiovascular disease at follow-up (21% vs 11%; p=0.04).
Conclusions:
- In the absence of overt cardiac disease, left or right BBB does not increase overall mortality.
- Isolated left BBB is associated with an increased risk of developing overt cardiovascular disease.
- Isolated left BBB is linked to increased cardiac mortality.
Abstract:
The purpose of this study was to determine the long-term outcome of patients with bundle branch block (BBB) who have no clinical evidence of cardiovascular disease. Among 110,000 participants in a screening program, 310 subjects with BBB without apparent of suspected heart disease were identified. Their outcome after a mean follow-up of 9.5 years was compared with that of 310 similarly screened age- and sex-matched controls. Among the screened population, isolated right BBB was more prevalent than isolated left BBB (0.18% vs 0.1%, respectively; p<0.001), and the prevalence of each abnormality increased with age (p<0.001). Total actuarial survival was no different for those with left BBB or right BBB and their respective controls. Cardiac mortality, however, was increased in the left BBB group when compared with their controls (p=0.01, log rank test). Left BBB, but not right BBB, was associated with an increased prevalence of cardiovascular disease at the follow-up (21% vs 11%; p=0.04). In the absence of clinically overt cardiac disease, the presence of left BBB or right BB is not associated with increased overall mortality. Isolated left BBB is associated with an increased risk of developing overt cardiovascular disease and increased cardiac mortality.