Acute coronary syndrome: Non-ST-segment elevation myocardial infarction, emerging perspective 2026

Non-ST-segment elevation acute coronary syndrome (NSTE-ACS), encompassing non-ST-segment elevation myocardial infarction (NSTEMI) and unstable angina, represents the predominant presentation of acute coronary syndromes and carries substantial morbidity and mortality. This comprehensive review synthesizes contemporary evidence alongside the latest recommendations from the 2023 European Society of Cardiology and 2025 American College of Cardiology/American Heart Association guidelines to provide an updated perspective on the diagnosis, risk stratification, and management of NSTE-ACS. The diagnostic framework integrates 12-lead electrocardiography, high-sensitivity cardiac troponin rapid algorithms, and validated risk tools – notably the Global Registry of Acute Coronary Events (GRACE) and Thrombolysis in Myocardial Infarction (TIMI) scores – to guide individualized invasive strategy selection and timing. Evidence supporting early invasive coronary angiography in high-risk patients is examined, alongside the evolving roles of coronary computed tomography angiography and cardiac magnetic resonance in select populations. Angiographic findings spanning obstructive and nonobstructive coronary artery disease, including myocardial infarction with non-obstructive coronary arteries, are reviewed, with emphasis on intravascular imaging-guided approaches to identify culprit mechanisms. Current evidence on complete versus culprit-only revascularization in multivessel disease, and the role of coronary physiology assessment, is critically appraised. The review further addresses management in specific subgroups – older adults (≥75 years), females, and patients with prior coronary artery bypass grafting – where unique challenges and evidence gaps persist. Antithrombotic strategies, including dual antiplatelet therapy initiation, P2Y12 inhibitor selection, pretreatment, and de-escalation approaches, are discussed in the context of balancing ischemic and bleeding risks. Secondary prevention measures – encompassing lipid-lowering therapy, sodium-glucose cotransporter-2 inhibitors, glucagon-like peptide-1 receptor agonists, colchicine, and exercise-based cardiac rehabilitation – are outlined in accordance with current guideline standards. The emerging role of artificial intelligence in ECG-based diagnosis and risk prediction is also highlighted. This review aims to bridge current evidence with clinical practice, emphasizing individualized, guideline-directed care for patients presenting with NSTE-ACS.