Echocardiographic assessment of the interventricular delay of activation and correlation to the QRS width in dilated cardiomyopathy

The aim of the study was to define criteria for left ventricular pacing in dilated cardiomyopathy (DCM) using an echocardiographic evaluation of inter ventricular electromechanical delay (IMD) and a correlation of IMD to QRS d uration. Standard 12-lead ECG and echocardiography with pulsed Doppler tiss ue imaging (DTI) were recorded in 35 DCM patients (mean age 58 +/- 11 years ) with QRS duration from narrow(80 ms) to broad (222 ms) patterns. The time for left ventricular activation was evaluated from the onset of QRS to the onset of aortic flow (Q-Ao) by standard pulsed Doppler (SP) or to the onse t of mitral annulus systolic wave (Q-Mit) (DTI). The time for right ventric ular activation was determined from the onset of QRS to the onset of pulmon ary flow (Q-Pulm) (SP) or to the onset of tricuspid annulus systolic wave ( Q-Tri) (DTI). (Q-Ao)-(Q-Pulm) and (Q-Mit)-(Q-Tri) determined IMD for each m ethod, respectively. QRS width and IMD showed correlation coefficients of r = 0.86 ([Q-Ao]-[Q-PulmD]) and r = 0.82 ([Q-Mit]-[Q-Tri]) (P less than or e qual to 0.001). Mean IMD of 77 +/- 15 ms (SP) and 88 +/- 26 ms (DTI) were n oted for QRS width above 150 ms. Left ventricle delayed activation was posi tively correlated to QRS widening with both methods, (r = 0.90, [Q-Ao]), (r = 0.83, [Q-Mit]) (P less than or equal to 0.001). In conclusion, QRS durat ion is a good marker of an interventricular mechanical asynchrony. Accordin g to IMD correction, left ventricular pacing may be mainly proposed to symp tomatic DCM patients with QRS duration > 150 ms.