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Bundle-Branch Block and In-Hospital Mortality in Acute Myocardial Infarction

Alan S. Go, MD; Hal V. Barron, MD; Amy Chen Rundle, MS; Joseph P. Ornato, MD; and Andrew L. Avins, MD, MPH
[+] Article and Author Information

For the National Registry of Myocardial Infarction 2 Investigators For author affiliations and current author addresses, see end of text. Requests for Reprints: Alan S. Go, MD, Division of Research, Kaiser Permanente Medical Care Program, 3505 Broadway Street, 12th Floor, Oakland, CA 94611; e-mail, axg@dor.kaiser.org. Current Author Addresses: Dr. Go: Division of Research, Kaiser Permanente Medical Care Program, 3505 Broadway Street, 12th Floor, Oakland, CA 94611.


Copyright ©2004 by the American College of Physicians


Ann Intern Med. 1998;129(9):690-697. doi:10.7326/0003-4819-129-9-199811010-00003
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Background: Left bundle-branch block (BBB) is considered an important predictor of poor outcome in patients with acute myocardial infarction, but the consequences of right BBB are not well understood.

Objectives: To 1) estimate the prevalence of left and right BBB in patients with myocardial infarction; 2) compare the clinical characteristics of and treatments received by patients with left, right, or no BBB; and 3) determine the independent association of left BBB and right BBB with in-hospital death.

Design: Retrospective cohort study.

Setting: Multicenter registry of 1571 U.S. hospitals.

Patients: 297 832 patients with acute myocardial infarction who had left, right, or no BBB on initial electrocardiography.

Measurements: Presence and type of BBB, clinical characteristics of patients, therapies given, and in-hospital death.

Results: Patients with left BBB (n = 19 967; 6.7%) or right BBB (n = 18 354; 6.2%) were older and had more comorbid illness and congestive heart failure than patients with no BBB. Among patients for whom thrombolytic therapy was clearly indicated, fewer patients with left or right BBB (16.6% and 32.0%, respectively) than patients with no BBB (66.5%) received this therapy (P < 0.001). Fewer patients with left or right BBB (60.6% and 67.3%, respectively) than patients with no BBB (75.6%) received aspirin within the first 24 hours (P < 0.001), and fewer patients with left or right BBB (23.9% and 31.8%, respectively) than patients with no BBB (40.4%) received β-blockers within the first 24 hours (P < 0.001). Unadjusted in-hospital mortality rates were almost twice as high for patients with left or right BBB (22.6% and 23.0%, respectively) as for patients with no BBB (13.1%) (P < 0.001). Compared with no BBB and no ST-segment elevation, left BBB was associated with a 34% increase (odds ratio, 1.34 [95% CI, 1.28 to 1.39]) and right BBB was associated with a 64% increase (odds ratio, 1.64 [CI, 1.57 to 1.71]) in the risk for in-hospital death, after adjustment for potential confounders.

Conclusions: In patients with acute myocardial infarction, prevalences of right and left BBB are similar. Patients with BBB have more comorbid conditions, are less likely to receive therapy, and have an increased risk for in-hospital death compared with patients with no BBB. Compared with left BBB, right BBB seems to be a stronger independent predictor of in-hospital death.

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