QRS duration and echocardiographic evidence of left ventricular dyssynchrony in patients with left ventricular systolic dysfunction.

OBJECTIVE: To determine the association between left ventricular (LV) dyssynchrony assessed by tissue Doppler imaging (TDI) in patients with left ventricular ejection fraction (LVEF) < 35% and prolonged ventricular depolarization on electrocardiography. STUDY DESIGN: A cross-sectional study. PLACE AND DURATION OF STUDY: The Aga Khan University, Karachi, from June to September 2007. METHODOLOGY: All patients with LVEF < 35% were included. Apical 2-D images were obtained in 4 chamber and 2 chamber views. TDI pulse wave Doppler parameters were measured from these 2 color-coded images. Time interval between the onset of QRS complex and the peak systolic velocity per region was derived. Patients with valvular heart disease, mitral annular calcification, atrial fibrillation and paced rhythm were excluded. Fischer's exact test was used to determine the association between QRS duration and left ventricular dyssynchrony. RESULTS: A total of 60 patients were included. Twenty one patients had QRS duration of > 120 msec. Out of those 21 patients, a total of 6 patients (28.6%) had evidence of dyssynchrony on TDI. Five patients (23.8%) had dyssynchrony on the basis of basal septal and basal lateral velocity difference (p=0.045) and 6 patients (28.6%) had evidence of dyssynchrony based on basal anterior and basal inferior velocity difference (p=0.018). Out of the remaining 39 patients with narrow QRS complex, only 2 patients (5.1%) had dyssynchrony on TDI. CONCLUSION: The study demonstrates a significant association between prolonged QRS duration and left ventricular dyssynchrony on TDI. Therefore, such patients should be screened for prolonged QRS duration on ECG before cardiac resynchronization therapy (CRT).