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

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