Consecutive electrocardiographic (ECG) analysis is very useful in acute coronary ischemia, but it is known that ECG patterns can be misleading in subjects with left ventricular hypertrophy, mainly during the repolarization phase. An automated system was developed to collect, store, and follow-up all heterogeneous data concerning a cohort of 1,898 subjects (1,039 men), 45-65 years old, 50% of whom were physically active. The reliability of several ECG markers of ischemia was tested during chronic follow-up study (1993-1995) in 23 healthy sedentary men without hypertension (group 1) recorded in our database, as well as in 9 subjects performing regular sporting activity (SA) (group 2). The same parameters were evaluated in the intensive care unit in nine patients affected by coronary artery disease, during either successful or unsuccessful thrombolytic therapy of acute myocardial infarction (AMI) (group 3). Twelve-lead ECGs were recorded, analyzed by the Hannover ECG system program, compressed, and stored according to the Standard Communication Protocol in each of the three groups. The changes in ST amplitude 20, 60, and 80 ms alter the J point were very small in each subject of groups 1 and 2, while upsloping from 1 to 10 mm in several leads was observed slowly, rapidly, or intermittently in group 3 patients during ischemia. The ST slope and the concordance of the T wave and ST amplitude were helpful in differentiating normal and SA subjects from AMI patients. These results, obtained in resting conditions, underline that the difference among ST-T abnormalities in subjects with left ventricular hypertrophy due to SA are consistently different from those observed in patients with AMI. The serial digital ECG can be helpful to underline these differences.