ABSTRACT Prediction of fatal arrhythmias in acute myocardial infarction (AMI) is extremely important. Objective: Create a differential diagnostic model for predicting sudden cardiac death in elderly patients with STEMI with the history of PCI. Methods: We studied 152 patients (143 men and 9 women), mean age 70.3±3.4 years, with STEMI after PCI; EF LV less than 50%. The patients were divided into 2 groups: those who died on the first day from SCD and those who survived. The QT interval and its parts were measured upon admission and after PCI. The control group consisted of 30 healthy individuals. Results: A model was developed for determining the level of risk of arrhythmic death on the first day from SCD after successful PCI based on ECG criteria using DA. The most informative for the differential diagnosis was a set of the following indicators: QTd, QTapcd, and SubTd. The most significant indicator is Sub Td. The following algorithms were developed: ROAD = Qtd x 0.3438 + QTapcd x 0.0842 - SubTd x 0.0864 - 19.5068, NROAD = Qtd x 0.1997 - QTapcd x 0.0148 + SubTd x 0.3261 - 20.893. Their practical implementation on models is proved. Conclusion: The creation of a “ROAD/NROAD” differential diagnosis model for predicting SCD in patients with STEMI after PCI suggests practical application at the prehospital stage in this category of patients for prophylactically fatal VA and SCD. Assessment of the possible development of adverse events in patients with STEMI after PCI is possible using the ECG method based on the use of indicators such as QTd, QTapcd, and SubTd at the prehospital stage.