Looking beyond ejection fraction

There has been considerable effort in the heart failure community to unearth parameters that quantify true myocardial function better than left ventricular ejection fraction (LVEF), a largely volumetric representation of global function. LVEF can be preserved despite significant myocyte dysfunction—as the myocardium is multi-layered, processes affecting one layer can be compensated for by others limiting remodelling, maintaining volumes and preserving LVEF. Therefore, it is no surprise that 50% of patients who present with heart failure have preserved LVEF. LVEF is also load dependent and can be preserved despite advanced myocardial disease, for example, in severe mitral regurgitation when afterload is reduced. Recently, the limitation of relying on a ‘normal’ LVEF to risk stratify patients with severe aortic stenosis (AS) has been demonstrated—with an LVEF of up to 60% still associated with worse survival.1 In these patients, small, hypertrophied LV cavities are associated with both circumferential and longitudinal fibre dysfunction, yet geometric factors serve to maintain a misleadingly normal LVEF.2

Imaging biomarkers of intrinsic contractility are clearly more desirable—with global longitudinal strain (GLS) a recent front runner. GLS detects abnormalities of the subendocardial fibres which is particularly relevant in patients with AS and concomitant LV concentric …