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Bundle branch block in patients with chronic coronary artery disease: angiographic correlates and prognostic
Insights
Bundle branch block in chronic coronary artery disease patients indicates more extensive disease and worse function. Left bundle branch block significantly predicts mortality, independent of other factors.
Area of Science:
- Cardiology
- Clinical Medicine
- Medical Diagnostics
Background:
- Bundle branch block (BBB) during acute myocardial infarction suggests left anterior descending artery ischemia.
- Prognostic implications of BBB are mainly studied in acute myocardial infarction, not chronic coronary artery disease (CAD).
Purpose of the Study:
- To investigate the association between BBB and coronary artery disease extent and location in patients with chronic CAD.
- To determine the independent prognostic value of BBB in patients with chronic CAD.
Main Methods:
- Analysis of electrocardiograms (ECGs) from 15,609 patients in the Coronary Artery Surgery Study (CASS).
- Identification of 522 patients with BBB who underwent coronary and left ventricular angiography.
- Follow-up for mortality over 4.9 years.
Main Results:
- Patients with BBB had more extensive CAD and poorer left ventricular function than those without BBB.
- No specific coronary stenosis location or wall motion abnormality predominated in BBB patients.
- Two-year mortality was >5x higher in left bundle branch block (LBBB) and ~2x higher in right bundle branch block (RBBB) compared to no BBB.
Conclusions:
- BBB in chronic CAD is associated with more severe disease but not a specific lesion location.
- LBBB is a strong independent predictor of mortality in chronic CAD patients.
- RBBB also predicts mortality, but LBBB carries a significantly higher risk.
Abstract:
The onset of bundle branch block during acute myocardial infarction is indicative of ischemia in the distribution of the left anterior descending coronary artery. However, whether patients with chronic coronary artery disease and bundle branch block have a predominance of left anterior descending artery lesions is not known. Similarly, the prognostic implications of bundle branch block have been studied primarily in the setting of acute myocardial infarction, and the independent prognostic implications of bundle branch block in patients with chronic coronary artery disease are not known. The electrocardiograms (ECGs) of 15,609 patients with chronic coronary artery disease who underwent coronary and left ventricular angiography as part of the Coronary Artery Surgery Study (CASS) were reviewed, and 522 patients with bundle branch block were identified. Patients with bundle branch block had both more extensive coronary artery disease and worse left ventricular function than did patients without bundle branch block. However, no particular location of coronary artery stenosis or left ventricular wall motion abnormality predominated in patients with bundle branch block. During a follow-up period of 4.9 +/- 1.3 years, 2,386 patients died. Actuarial probability of mortality at 2 years in patients with left bundle branch block was more than five times that in patients without bundle branch block (p less than 0.0001), and in patients with right bundle branch block the mortality rate was approximately twice that in patients without bundle branch block (p less than 0.0001). Stepwise Cox regression analysis showed that left bundle branch block, but not right bundle branch block, was a strong predictor of mortality, independent of degree of heart failure, extent of coronary disease and other variables (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)