Left ventricular twist in patients with left bundle branch block: Missing the obvious in electromechanical coupling

The recent advent of imaging modalities capable of myocardial mechanical assessment, such as speckle tracking echocardiography, has offered insight for understanding the earlier and subclinical phases of cardiac dysfunction beyond the conventional parameters, such as ejection fraction (EF), and Doppler based methods (1, 2). However, myocardial functions are equally dependent on myocardial electrical properties because electromechanical coupling is crucial for an efficient cardiac contraction-relaxation cycle. One clear example of this concept is left bundle branch block (LBBB) that significantly influences left ventricular (LV)-electrical activation and contraction; the outcome is a dyssynchronous uncoordinated myocardial contraction that can progress to LV dilation and remodeling (3). In this issue, Yılmaz et al. (4) study the effects of LBBB on left ventricular twist (LVT), a crucial component of myocardial systolic and diastolic efficiency and the cross-road of both mechanical and electrical properties of the heart. To understand the significance of such an interesting question, a review of the mechanical and electrical concepts would be useful.