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Mayo Clin Proc. 2005 Dec;80(12):1585-90.

Risk factor implications of incidentally discovered uncomplicated bundle branch block.

Author information

1
Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, MN 55905, USA. miller.wayne@mayo.edu

Abstract

OBJECTIVE:

To evaluate the long-term outcome of a community-based patient population with incidentally discovered asymptomatic and uncomplicated bundle branch block (BBB).

PATIENTS AND METHODS:

A retrospective observational cohort study was undertaken of patients in Olmsted County, Minnesota, who were evaluated between 1975 and 1999 and were incidentally diagnosed as having BBB. We performed Kaplan-Meier analyses of all-cause mortality and development of first cardiac morbidity after the diagnosis of BBB, along with matched control group comparisons.

RESULTS:

A total of 723 patients with left BBB (LBBB) (58.1%) and right BBB (41.9%) met criteria. Mortality was higher in patients with BBB compared with controls (absolute difference of approximately 10% over 20 years; hazard ratio = 1.27; confidence interval, 1.02-1.58; P=.03) as was the development of first cardiac-related morbidity (hazard ratio = 1.32; confidence interval, 1.14-1.54; P<.001). Patients with BBB and without the risk factors of diabetes, hypertension, and/or hypercholesterolemia showed increased long-term mortality compared with matched controls (no BBB) also without risk factors (P=.02). However, comparable mortality was shown between patients with BBB who did not have these risk factors and matched control patients who had these risk factors. The risk of developing cardiac-related morbidity also was increased in the presence of BBB, particularly LBBB.

CONCLUSIONS:

Uncomplicated asymptomatic BBB (notably LBBB) with normal left ventricular ejection fraction is not benign. Our findings indicate that the presence of isolated BBB denotes a high-risk patient subgroup that has a compromised long-term outcome comparable to patients with conventional cardiovascular risk factors.

PMID:
16342651
DOI:
10.4065/80.12.1585
[Indexed for MEDLINE]

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