DIAGNOSIS OF ACUTE MYOCARDIAL INFARCTION WITHOUT ST-SEGMENT ELEVATION (NSTEMI)

Abstract

Non-ST-segment elevation myocardial infarction (NSTEMI) is currently the most frequent presentation of acute coronary syndromes and constitutes a significant diagnostic challenge in clinical practice. This study aims to review recent evidence related to the diagnosis and risk stratification of NSTEMI. This is a narrative literature review based on articles published between 2021 and 2025 in the PubMed database and in high-impact scientific journals. The current diagnosis is based on the association between a clinical picture compatible with myocardial ischemia, absence of persistent ST-segment elevation on the electrocardiogram, and elevation of cardiac biomarkers, especially high-sensitivity troponins, assessed through serial measurements. However, recent evidence demonstrates that a portion of patients classified as NSTEMI may present with acute coronary occlusion not identified by traditional criteria, which has driven the discussion about new conceptual models, such as the OMI/NOMI paradigm. It is concluded that the diagnosis of NSTEMI requires an integrated approach between clinical evaluation, biomarkers, and refined electrocardiographic interpretation, in addition to continuous monitoring of the ischemic condition and adequate risk stratification to define the therapeutic strategy.