ABSTRACT
Objective: To explore correlation between QRS complex duration and left ventricular ejection fraction (LVEF) in patients with complete left bundle branch block (CLBBB).Methods: A total of 213 patients, who were diagnosed as left bundle branch block by ECG in our hospital from Feb 2012 to Jun 2013, were selected.According to QRS complex duration, patients were divided into CLBBB group (n=182) and incomplete left bundle branch block (ICLBBB) group (n=31).Linear correlation analysis was used to analyze the correlation between QRS complex duration and LVEF, and receiver operating characteristic curve (ROC) was used to analyze optimal cutoff point of QRS complex duration for predicting LVEF<50%.Results: Compared with ICLBBB group, there was significant rise in QRS complex duration [(104.61±8.85) ms vs.(149.36±17.25) ms] and significant reduction in LVEF [(54.26±4.96)% vs.(45.22±12.57)%] in CLBBB group, P<0.01 both.Linear correlation analysis indicated that QRS complex duration was significant inversely correlated with LVEF (r=-0.55, P=0.001) in CLBBB patients.ROC analysis indicated that optimal cutoff point of QRS complex duration for predicting LVEF<50% was 151ms, the area under the curve was 0.79 (P=0.001),its sensitivity was 68.1% and specificity was 83.5%.Conclusion: QRS complex duration is significant inversely correlated with LVEF in CLBBB patients, which can be used as a simple index predicting reduced LVEF.