To investigate the natural history of regional dyssynergy and left ventricular size after myocardial infarction, 57 patients with a first Q wave myocardial infarction (18 anterior, 35 inferior, and four apical by echocardiography) were studied by two-dimensional echocardiography and compared with 30 control patients. Measurements from the echocardiograms were used to construct maps of the left ventricular endocardial surface from which the endocardial surface area index (ESAi) and the percent of the endocardial surface area involved by abnormal wall motion (%AvAWM) were calculated. The maps from entry and 3-month echocardiograms were used to classify patients based on changes in ESAi and abnormal wall motion. Two subgroups of patients were identified at entry -those with a normal ESAi (group 1, n =50) and those with an increased ESAi (group 2, n =7 (Circulation 1990;82:484-494) T wo-dimensional echocardiography is an ideal noninvasive method for visualizing the changes in left ventricular structure and function that occur during myocardial ischemia and after infarction.1-10 Clinical studies with this technique have demonstrated a clear relation between the location and extent of echocardiographically defined regional dysfunction and electrocardiographic infarct location,1-3,5-8 pathological size of infarction,,'9 clinical status of the patient,2,6,7 occurrence of complications,2,3 and survival