DIAGNOSIS OF ACUTE MYOCARDIAL INFARCTION WITHOUT ST-SEGMENT ELEVATION (NSTEMI): CLINICAL AND ELECTROCARDIOGRAPHIC CRITERIA

Abstract

Acute Coronary Syndrome (ACS) is the leading cause of global mortality, with Non-ST-Segment Elevation Myocardial Infarction (NSTEMI) being twice as frequent as STEMI. Traditionally, the diagnosis of NSTEMI is based on the absence of persistent ST-segment elevation on the ECG, associated with elevated troponins. However, the STEMI/NSTEMI paradigm is limited, since 25% to 34% of patients classified as NSTEMI present with Myocardial Occlusion (MIO) and require immediate reperfusion. This study, a narrative literature review in the PubMed database, aimed to synthesize and analyze the most recent evidence on the diagnosis of NSTEMI. The results reinforce the transition to the OMI/NOMI model, highlighting the importance of identifying electrocardiographic "STEMI equivalents," such as De Winter's pattern, Wellens' syndrome, and hyperacute T waves. Although ultrasensitive troponins optimize early diagnosis, they do not distinguish the etiology of infarction nor identify occlusions in real time. Rigorous risk stratification, with scores such as GRACE, is fundamental to guiding the invasive strategy (emergent or within 24 hours). The future management of NSTEMI requires the integration of diagnostic advances, improved risk stratification, and personalized therapies, with a continued focus on secondary prevention and vulnerable populations, such as elderly patients.