Related Experiment Videos
Bundle branch block as a predictor of long-term survival after acute myocardial infarction
E S Brilakis1, R S Wright, S L Kopecky
1Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
Insights
Bundle branch block (BBB) affects nearly 13% of acute myocardial infarction (AMI) patients. While not an independent predictor, BBB indicates higher mortality and lower ejection fractions, serving as a key clinical marker.
Area of Science:
- Cardiology
- Electrocardiography
- Public Health
Background:
- Bundle branch block (BBB) is a common electrocardiogram (ECG) finding.
- Its prevalence and prognostic implications in acute myocardial infarction (AMI) require further community-based investigation.
Purpose of the Study:
- To determine the prevalence of BBB on presenting ECGs in AMI patients.
- To compare clinical characteristics, treatment, and outcomes between AMI patients with and without BBB.
- To assess the association of BBB with in-hospital and long-term mortality.
Main Methods:
- Retrospective analysis of 894 consecutive AMI patients from Olmsted County, Minnesota (1988-1998).
- ECGs were analyzed for the presence of left BBB (LBBB) or right BBB (RBBB).
- Clinical data, treatments, and mortality (in-hospital and post-discharge) were compared across groups.
Main Results:
- BBB was present in 12.6% of AMI patients (5.9% LBBB, 6.7% RBBB).
- Patients with BBB were older, had more comorbidities, received less reperfusion therapy, but more ACE inhibitors.
- BBB patients had lower predischarge ejection fractions and higher unadjusted in-hospital and long-term mortality rates.
Conclusions:
- BBB is a significant finding in AMI patients, associated with poorer left ventricular function.
- Although not an independent mortality predictor in multivariate analysis, BBB presence is a valuable clinical marker for increased mortality risk.
- Community-based data highlight the prognostic importance of recognizing BBB in AMI management.
Abstract:
Using a community-based population of patients with acute myocardial infarction (AMI), we sought to: (1) determine the prevalence of bundle branch block (BBB) on the presenting electrocardiogram (ECG), (2) compare the clinical characteristics and the treatment administered to patients with and without BBB, and (3) determine the association of BBB with mortality. We analyzed the admission ECGs of 894 consecutive patients with AMI from Olmsted County, Minnesota, seen at our institution from January 1988 to March 1998. Of these, 53 had left BBB (LBBB) (5.9%) and 60 had right BBB (RBBB) (6.7%). Patients with BBB were more likely to be older, have a history of AMI or hypertension, and to be in Killip class >I at presentation. They were less likely to receive primary reperfusion therapy, beta blockers, or heparin, but more likely to receive angiotensin-converting enzyme inhibitors. They had lower mean predischarge ejection fractions (38 +/- 16% vs 50 +/- 15%, p <0.0001). In-hospital mortality was 13.3%, 17.0%, and 9.1% for patients with RBBB, LBBB, and no BBB, respectively (p = 0.11). Respective postdischarge survival at 1, 3, and 5 years was 80%, 60%, and 50% in the RBBB group, 78%, 56%, and 51% in the LBBB group, and 92%, 85%, and 76% in the group without BBB (p <0.0001). Although BBB was not an independent predictor of mortality on multivariate analysis, the presence of transient or persistent BBB with AMI is an easily recognized clinical marker of increased mortality. Our conclusion from this study is that in a community-based population, patients who had LBBB or RBBB at the time of AMI had lower predischarge ejection fractions and higher in-hospital and long-term unadjusted mortality.