Do we overestimate left ventricular ejection fraction by two‐dimensional echocardiography in patients with left bundle branch block?

Aims Left bundle branch block (LBBB) causes a dyssynchronized contraction of left ventricle. This is a kind of regional wall‐motion abnormality and measuring left ventricular ejection fraction (LVEF) by two‐dimensional (2D) echocardiography could be less reliable in this particular condition. Our aim was to evaluate the role of dyssynchrony index (SDI), measured by three‐dimensional (3D) echocardiography, in assessment of LVEF and left ventricular volumes accurately in patients with LBBB. Methods and Results In this case–control study, we included 52 of 64 enrolled participants (twelve participants with poor image quality were excluded) with LBBB and normal LVEF or nonischemic cardiomyopathy. Left ventricular ejection fraction (LVEF) and left ventricular volumes were assessed by 2D (modified Simpson's rule) and 3D (four beats full volume analysis) echocardiography and the impact of SDI on results were evaluated. In patients with SDI ≥6%, LVEF measurements were significantly different (46.00% [29.50–52.50] vs 37.60% [24.70–45.15], P