Comparison Of QRS Duration With Intraventricular Dyssynchrony As Measured By Tissue Doppler Imaging In Heart Failure Patients

Aims The study aimed at evaluating the relationship between QRS duration and intraventricular systolic dyssynchrony in heart failure patients.Methods and Results Echocardiography and tissue Doppler imaging (TDI) were performed in 26 consecutive patients with advanced left ventricular dysfunction (LVEF=35%); 18 patients had a normal QRS duration (Group1), and 8 patients had left bundle branch block or a prolonged QRS duration of >120 ms (Group 2). Echocardiography with tissue Doppler imaging was performed using a six basal, six mid-segmental models, measuring time to peak systolic velocity in 12 segments of the left ventricle walls. Intraventricular systolic dyssynchrony (defined by the presence of 60 ms or greater difference in time to peak velocity between any two points of the left ventricle walls) was observed in 72% (13/18) of patients in group 1 and 87% (7/8) of patients in group 2, (x~2 = 0.70, p = 0.403). There was no significant difference of intraventricular mechanical delay (IVMD, maximal difference in time to peak systolic velocity among all 12 left ventricular segments) between group 1 and group 2 (73±36 ms vs 97±38 ms, t = 1.54, p = 0.136). No significant correlation was found between QRS duration and intraventricular dyssynchrony (r = 0.29, p = 0.146), though an increasing trend of IVMD along with QRS duration was seen. However, the correlation analysis showed that there was a positive correlation between the end systolic volume (ESV) and IVMD (r = 0.40, p = 0.043), and a negative correlation between the ejection fraction (EF) and IVMD (r = 0.45, p = 0.021).Conclusions A substantial proportion of heart failure patients with a slightly prolonged QRS or even with normal conduction may exhibit ventricular dyssynchrony. There is no correlation between the electrical delay represented by the QRS duration and the actual intraventricular conduction delay measured by tissue Doppler imaging. As QRS complex duration is not a determinant of systolic asynchrony, it implies that assessment of intraventricular synchronicity by TDI is probably more important than QRS duration in considering cardiac resynchronisation treatment.