QRS dispersion: an electrocardiographic index of systolic left ventricular dysfunction in patients with left bundle branch block.

The presence of complete left bundle branch block (LBBB) in patients with congestive heart failure has been proposed to be a factor that negatively affects left ventricular (LV) systolic function. The aim of this study was to evaluate the relative predictive value of QRS dispersion (QRSD) and QRS duration (QRSd) in relation to systolic performance of the left ventricle. The ejection fraction of 130 consecutive patients with LBBB was evaluated by standard echocardiographic methods, whereas QRSd and QRSD were measured. It was demonstrated that QRSD in patients with complete LBBB is strongly related to LV contractility. We, therefore, suggest that this simple electrocardiographic index may serve as a useful screening test for detection of patients with LV systolic dysfunction.