Author + information
- Received August 11, 1986
- Revision received December 19, 1986
- Accepted January 9, 1987
- Published online July 1, 1987.
- Roger A. Freedman, MD†,**,
- Edwin L. Alderman, MD, FACC‡,
- L. Thomas Sheffield, MD, FACC§,
- Mark Saporito, BS‖,
- Lloyd D. Fisher, PhD, FACC‖,
- Principal Investigators for the Coronary Artery Surgery Study and Their Associates*
- ↵**Address for reprints: Roger A. Freedman, MD, Cardiology Division, University of Utah Medical Center. Salt Lake City, Utah 84132.
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 < 0.0001), and in patients with right bundle branch block the mortality rate was approximately twice that in patients without bundle branch block (p < 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 < 0.0001).
These results indicate that although bundle branch block in the setting of chronic coronary artery disease is generally associated with widespread left ventricular wall motion abnormalities, it is not uniquely associated with a lesion of the left anterior descending artery or with motion abnormality of the anterior left ventricle. Thus, most cases of bundle branch block in this setting may not be the result of infarction of the proximal conduction system, as they are when developing during acute myocardial infarction. Presence of left bundle branch block is an important independent predictor of mortality during long-term follow-up.
- Received August 11, 1986.
- Revision received December 19, 1986.
- Accepted January 9, 1987.
- American College of Cardiology Foundation