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Eur Heart J. 2006 Jan;27(1):21-8. Epub 2005 Nov 3.

Prognostic differences between different types of bundle branch block during the early phase of acute myocardial infarction: insights from the Hirulog and Early Reperfusion or Occlusion (HERO)-2 trial.

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  • 1Cardiovascular Research Unit, Green Lane Cardiovascular Service, Auckland City Hospital, Private Bag 92024, Auckland 1030, New Zealand.

Abstract

AIMS:

Bundle branch block (BBB) early during acute myocardial infarction (AMI) is often considered high risk for mortality. Little is known about how different BBB types influence prognosis.

METHODS AND RESULTS:

The HERO-2 trial recruited 17 073 patients with ischaemic symptoms lasting >30 min and either ST elevation with or without right bundle branch block (RBBB) or presumed-new left bundle branch block (LBBB). Electrocardiograms were performed before and 60 min after the start of fibrinolytic therapy. Using patients with normal intraventricular conduction as a reference, odds ratios (ORs) for 30-day mortality were calculated for different BBB types (LBBB, RBBB with anterior AMI, and RBBB with inferior AMI) present at randomization and/or 60 min, with adjustment for recruitment region, pre-infarction characteristics, time to randomization, hemodynamics, and Killip class. At randomization, the 873 patients (5.11%) with BBB had worse baseline characteristics than patients without BBB. In patients presenting with LBBB (n=300), the ORs for 30-day mortality were 1.90 (95% CI 1.39-2.59) before and 0.68 (0.48-0.99) after adjustment for other prognosticators. In patients presenting with RBBB (n=415) and anterior AMI, the ORs were 3.52 (2.82-4.38) before and 2.48 (1.93-3.19) after adjustment. In patients presenting with RBBB and inferior AMI (n=158), the ORs were 1.74 (1.06-2.86) before and 1.22 (0.71-2.08) after adjustment. Within 60 min, 143 patients (0.92%) developed new BBB. The adjusted ORs for 30-day mortality were 2.97 (1.16-7.57) in the 25 patients with new LBBB, 3.84 (2.38-6.22) in the 100 with new RBBB and anterior AMI, and 2.23 (0.54-9.21) in the 18 with new RBBB and inferior AMI.

CONCLUSION:

RBBB accompanying anterior AMI at presentation and new BBB (including LBBB) early after fibrinolytic therapy are independent predictors of high 30-day mortality. These electrocardiographic features should be considered in risk stratification to identify high-risk patients.

PMID:
16269419
[PubMed - indexed for MEDLINE]
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