Left bundle branch block: A predictor of poor left ventricular function in coronary artery disease

Clinical, coronary arteriographic, and hemodynamic studies were performed in 55 patients with left bundle branch block (LBBB) and coronary artery disease and were compared with 110 patients consecutively matched for age and sex with ischemic heart disease but without LBBB. No significant differences were found in duration of symptoms or frequency of prior myocardial infarction, hypertension, or diabetes mellitus; however, the LBBB patients had a significantly (p < 0.001) higher frequency of congestive heart failure (38.2% vs 11.8%) and cardiomegaly (63.6% vs 25.5%). An evaluation of severity of the coronary disease on the basis of subtotal vs total obstructive lesions, number of vessels involved, total coronary score, and individual coronary arteries involved revealed no significant differences between the groups. The LBBB patients had significantly (p < 0.001) greater impairment of left ventricular function as reflected by the end-diastolic volume (107 ± 43 vs 79 ± 30 ml/m2), ejection fraction (0.35 ± 0.19 vs 0.59 ± 0.18), and frequency of an abnormal contractile pattern (91% vs 61%). Evaluating the LBBB patients on the basis of the QRS width and axis revealed no significant intragroup differences in clinical profile, severity of coronary disease, or left ventricular dysfunction. A prolonged PR interval (≥0.20 second) was associated with more severe coronary artery disease and an enlarged heart. This study indicates that coronary artery disease associated with LBBB identifies patients with severe left ventricular dysfunction.