Pengaruh Faktor Ekstrakardiak terhadap Timbulnya Late Potentials pada Signal-Averaged Electrocardiography Awal Perawatan Pasien Infark Miokardium Anterior di Intensive Cardiac Care Unit = Effects of Extracardiac Factors in Signal-Averaged Electrocardiography-Measured Late Potentials from Early Anterior Myocardial Infarction in Intensive Cardiac Care Unit.