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Right bundle branch block: long-term prognosis in apparently healthy men
Insights
Complete right bundle branch block in healthy men does not impact long-term cardiac health or mortality. This finding suggests it
Area of Science:
- Cardiology
- Electrophysiology
- Gerontology
Background:
- Complete right bundle branch block (cRBBB) is a common electrocardiographic finding.
- Its long-term cardiac prognosis in asymptomatic individuals is not well-established.
- The Baltimore Longitudinal Study on Aging (BLSA) provides a unique population for studying aging-related cardiac conditions.
Purpose of the Study:
- To assess the long-term cardiac prognosis of clinically healthy men with cRBBB.
- To compare cardiac morbidity and mortality in men with cRBBB versus a matched control group.
- To investigate the association of cRBBB with cardiac risk factors, exercise tolerance, and conduction abnormalities.
Main Methods:
- Retrospective analysis of 24 men with cRBBB from the BLSA cohort (n=1,142).
- Follow-up period averaged 8.4 years.
- Comparison with an age-matched control group, assessing antecedent risk factors, clinical events, exercise capacity, and electrocardiographic parameters.
Main Results:
- No significant differences in coronary risk factors, obstructive lung disease, or major cardiac events (angina, myocardial infarction, heart failure, cardiac death) between groups.
- Maximal aerobic exercise tolerance and chronotropic response were similar in both groups.
- Significant increases in leftward axis deviation (46% vs 15%) and PR interval prolongation (29% vs 6%) were observed in the cRBBB group.
Conclusions:
- Complete right bundle branch block in asymptomatic men appears to be a manifestation of a primary conduction system abnormality.
- cRBBB in this cohort did not demonstrate an adverse effect on long-term cardiac morbidity or mortality.
- Further investigation into the electrophysiological significance of associated conduction abnormalities is warranted.
Abstract:
The long-term cardiac prognosis of 24 clinically healthy men with complete right bundle branch block, identified from the 1,142 men constituting the population of the Baltimore Longitudinal Study on Aging, was assessed over a follow-up period averaging 8.4 years. When compared with a control group matched for age at which right bundle branch block appeared (mean +/- standard deviation 64.0 +/- 13.5 years), men with right bundle branch block showed no difference in the prevalence of antecedent coronary risk factors or obstructive lung disease. The incidence of angina pectoris, myocardial infarction, valvular heart disease, cardiomegaly, congestive heart failure, advanced heart block or cardiac death in these men did not differ from that of the control group over the observation period. Furthermore, at the latest follow-up study, maximal aerobic exercise tolerance and chronotropic response to maximal exercise were not impaired in men with right bundle branch block relative to control men (9.1 +/- 2.2 versus 7.3 +/- 3.0 minutes and 150.3 +/- 23.5 versus 147.7 +/- 20.7 beats/minute, respectively). However, axis deviation leftward of -30 degrees was present in 46% of men with right bundle branch block but in only 15% of control subjects at latest follow-up (probability [p] less than 0.01). Although the PR interval lengthened by 40 ms or more developed in only 6% of control subjects over the observation period, such prolongation occurred in 29% of men with right bundle branch block (p less than 0.05). These results support the concept that right bundle branch block in these asymptomatic men is a manifestation of a primary abnormality of the cardiac conduction system but has no demonstrable adverse effect on long-term cardiac morbidity or mortality.