Interventricular and intraventricular dyssynchrony are common in heart failure patients, regardless of QRS duration

The study aimed at evaluating the prevalence of interventricular and intraventricular contractile dyssynchrony in heart failure patients with either normal or prolonged QRS duration.

Echocardiography and tissue Doppler imaging (TDI) were performed in 158 consecutive patients with advanced left ventricular dysfunction (LVEF<35%); 61 patients had a normal QRS duration (Group 1), 21 patients had left bundle branch block with a QRS duration between 120 and 150 ms (Group 2) and 76 patients had a QRS duration #10878;150 ms (Group 3). Interventricular dyssynchrony (defined by the presence of an interventricular mechanical delay greater than 40 ms) was found in 12.5%, 52.4% and 72% of patients in Group 1, 2 and 3, respectively (p < 0.001). Intraventricular dyssynchrony (defined by the presence of one or more differences greater than 50 ms among regional pre-ejection periods) was observed in 29.5%, 57.1% and 71% of patients in Group 1, 2 and 3, respectively (p < 0.001). No relationship was found between interventricular and intraventricular dyssynchrony.

A substantial proportion of heart failure patients with a slightly prolonged QRS or even with normal conduction may exhibit ventricular dyssynchrony. Both standard echocardiography and TDI are necessary to describe the entire spectrum of mechanical abnormalities due to dyssynchrony.