Assessment of left ventricular systolic function in aortic stenosis and prognostic implications

Abstract

This editorial refers to ‘Global longitudinal strain is a strong independent predictor of all-cause mortality in patients with aortic stenosis’ by L.G. Kearney et al ., doi:10.1093/ehjci/jes115. Left ventricular (LV) ejection fraction, most commonly assessed with two-dimensional echocardiography, is an important prognostic determinant of many cardiovascular diseases. The decision of implanting specific cardiovascular devices, such as cardiac resynchronization therapy or implantable cardioverter defibrillator, recommending valvular surgery or chemotherapy relies on the LV ejection fraction. However, the accumulating evidence shows that LV ejection fraction is an imperfect measure of LV systolic function since it simply reflects the changes in the LV cavity volume and does not take into consideration the complex architecture of the LV.1,2 The LV myocardial fibre changes the three-dimensional spatial orientation from a right-handed helix in the subendocardial region to a left-handed helix in the subepicardium.1 This counterclockwise and clockwise spiral muscle configuration results in a characteristic three-dimenisonal LV deformation with shortening in the longitudinal and circumferential directions, thickening in the radial direction, and twist in the circumferential-longitudinal plane and permits LV emptying and filling with optimal mechanical efficiency. Thus, 15% of myofibre shortening during systole results in 40% myocardial wall thickening and >60% change in the LV ejection fraction in the normal heart.3 In addition, the extracellular collagen matrix of the myocardium supporting this myofibre arrangement is key to maintain the LV shape and size. Any change in the myofibre alignment or extracellular matrix may lead to LV dysfunction. Current imaging techniques, such as diffusion tensor and tagged magnetic resonance imaging and speckle tracking, permit non-invasive evaluation of the LV spiral muscle configuration and quantification of LV shortening, thickening, and twisting deformations. Particularly, speckle tracking echocardiography permits accurate assessment of multidirectional LV …