A lot of acquired data concerning the prognostic factors of post-infarction mortality dates from the pre-thrombolysis era. This mortality has considerably decreased since the active management of the acute phase of myocardial infarction. This has made it more complex to evaluate the post-infarction electrical risk and may have reduced the need. However, it is not less true that the assessment of the post-infarction risk necessitates a study of each factor predisposing to severe ventricular arrhythmias and sudden death: myocardial ischaemia, left ventricular dysfunction and electrical instability. The latter parameter may be assessed by non-invasive (ventricular extrasystoles, late ventricular potentials, heart rate variability, the baroreflex and the QT interval) and invasive methods (programmed ventricular stimulation). The association of these results has an excellent negative predictive value, and also improves the positive predictive value which, nevertheless, remains insufficient for expensive prophylactic measures associated with a certain morbidity, for example the implantation of a defibrillator device, to be taken.