Anatomical studies have demonstrated that there are three components to the musculature of the left ventricle, which are arranged longitudinally. These are the papillary muscles, and fibres within the ventricular wall, dominantly subendocardially, and to a lesser extent subepicardially.1 The important contribution of longitudinally arranged fibres to overall ventricular function has been recognised for many years. Surgeons now try hard to preserve papillary muscle function in both mitral valve repair and replacement, and patients do better for it. Drugs which improve longitudinal function can produce beneficial effects in patients with ventricular disease.2 Both the extent and timing of shortening and thickening of longitudinal fibres is essential to normal systolic function. And yet, despite the ease with which longitudinal ventricular function can be assessed, it has, until relatively recently, been neglected both in the literature and in clinical practice.

In this issue of Heart, Andersson and colleagues describe a double blind trial of metoprolol treatment in patients with ventricular disease, in which they show increases in the amplitude of atrioventricular plane displacement during treatment.3 These increases were associated with a reduction in pulmonary capillary wedge pressure and predicted increases in ejection fraction. The …