Chronic myocardial infarction (CMI) may create, due to structural heterogeneity, abnormal electrophysiological substrates which trigger re-entrant life-threatening ventricular arrhythmias.Methods: Electrical instability is assessed using body surface mapping (BSM) [multipolar isointegral QRST maps (mp IQRST)] and 12-lead ECG (QT dispersion: QTd: the difference between maximal and minimal QT interval). The aim was to find the relation between mp IQRST and QTd in CMI patients.Results: The 32 CMI patients, underwent 12-lead ECG and 64-lead BSM. The 80% (25) of the patients had mp IQRST maps. QTd was larger in patients with mp than those with dipolar maps (dp): 170±20 ms in mp vs 94±19 ms in dp, respectively. The latter, mp IQRST was associated with a decrease of maximum and a stronger minimum.Conclusions: Multipolar IQRST is associated with a loss of maximum values and increased absolute values of the minimum in CMI patients. IQRST and QTd provide similar information in predicting postinfarction arrhythmia risk.