NonSTelevation

Non-ST elevation refers to a group of acute coronary syndromes characterized by the absence of ST-segment elevation on electrocardiography. The two main clinical entities are non-ST-elevation myocardial infarction (NSTEMI) and unstable angina due to non-ST-elevation acute coronary syndrome (NSTE-ACS). They arise from rupture or erosion of a vulnerable atherosclerotic plaque with partial occlusion or reduced blood flow, causing myocardial ischemia without a full occlusion of a coronary artery.

Electrocardiographic changes may include ST-segment depression and/or T-wave inversion; in many cases the ECG is nondiagnostic. Diagnosis depends on cardiac troponin levels: NSTEMI shows elevated troponin, whereas unstable angina has no durable troponin rise. High-sensitivity troponin assays improve detection of minor myocardial injury. Diagnosis also relies on clinical presentation, ECG findings, and risk assessment.

Risk stratification uses clinical history, ECG, troponin results, and scoring systems such as GRACE or TIMI to guide management. NSTE-ACS must be distinguished from STEMI, which typically requires immediate reperfusion therapy.

Management integrates antithrombotic and anti-ischemic strategies with consideration of revascularization. Core elements include dual antiplatelet therapy (aspirin plus a P2Y12 inhibitor), anticoagulation (such as heparin), statin therapy, beta-blockers, and nitrates as needed. An early invasive strategy with coronary angiography and possible revascularization (percutaneous intervention or surgery) is recommended for high-risk patients within 24 hours; low-risk patients may undergo noninvasive testing to guide therapy. Thrombolysis is not indicated for NSTE-ACS.

Prognosis varies with risk factors and timeliness of treatment. Compared with stable angina, NSTEMI carries a higher short-term risk, but appropriate medical therapy and timely revascularization have improved outcomes.