[Changes in late potentials in the time period after myocardial infarct]. 
Late potentials are thought to be a non-invasive marker of discrete morphologic and electrophysiologic changes of the ventricular myocardium caused by fibrosis due to myocardial infarction.  To find out whether there are significant changes in the signal-averaged ECG (SA ECG) over one year we examined 30 patients following myocardial infarction.  When compared to the initial findings, significantly decreased incidence of late potentials was found after one year.  Most of the changes in the filtered QRS were located in the terminal portion of the fQRS--in the area of low amplitude signals.  Significant differences were noted in the changes found in patients with anterior myocardial infarction (MI) compared with the changes found in patients with posterior MI.