Although many advances have been made in the comprehension of pathophysiological details, our principal understanding of ventricular arrhythmia in ischaemic heart disease is still based on the classical concept of “arrhythmic triangle”.1 2 It postulates that arrhythmia appears under a particular combination of proarrhythmic substrate, triggers, and modulators.

Most recent studies of this concept concentrated on both explanation and characterisation of arrhythmia-favouring modulators, ranging from advanced studies of cardiac autonomic status to abnormalities in repolarisation processes of ventricular myocytes.3^–5 Less attention has recently been given to electrocardiographic assessment of arrhythmic triggers,6 7 while practically all recent studies of proarrhythmic substrate utilised programmed ventricular stimulation,8 although its practical value now appears somewhat less strong than initially expected. Fairly little progress has been made in electrocardiographic non-invasive assessment of proarrhythmic substrate since the period of intensive investigations of signal-averaged electrocardiography.9 It is therefore pleasing that a new electrocardiographic technique is described by Elgarhi et al 10(see article online only) in this issue of the Journal, again aimed at advancing our understanding of proarrhythmic substrate.

As reported by Elgarhi et al, in agreement with previous technically orientated publications,11 healthy subjects as well as ischaemic heart …