Cardiology · Acute Coronary Syndrome
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An NSTEMI is defined by the presence of elevated cardiac troponins in the setting of ischemic symptoms without ST-segment elevation on the 12-lead ECG.
Aspirin is given immediately in NSTEMI; a P2Y12 inhibitor (e.g., ticagrelor or clopidogrel) completes dual antiplatelet therapy (DAPT), typically given once coronary anatomy is known when angiography is planned within 24 hours; routine pretreatment before angiography is only a weak (2b) option per ACC/AHA 2025 when angiography will be delayed >24 hours.
Anticoagulation with unfractionated heparin, enoxaparin, or fondaparinux is recommended (parenteral anticoagulation: ACC/AHA 2025, Class 1) to prevent further thrombus propagation.
Beta-blockers are indicated within 24 hours to reduce myocardial oxygen demand and the risk of ventricular arrhythmias.
High-intensity statin therapy (e.g., atorvastatin) should be initiated as early as possible to provide plaque stabilization and long-term cardiovascular risk reduction.
An immediate invasive strategy (angiography within 2 hours) is indicated for very-high-risk features such as hemodynamic instability or refractory angina, whereas an early invasive strategy (within 24 hours) is used for high-risk features such as dynamic ST-segment changes or a rising troponin.
Nitroglycerin is used for symptomatic relief of ischemic chest pain but does not provide a mortality benefit in the acute setting.
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A 68-year-old male with a history of hypertension and hyperlipidemia presents to the emergency department with 2 hours of substernal chest pressure radiating to his left jaw. His ECG shows ST-segment depression in leads V4-V6 but no ST-segment elevation. His initial troponin I is significantly elevated at 1.5 ng/mL. He is currently hemodynamically stable with a blood pressure of 135/85 mmHg and is pain-free after sublingual nitroglycerin. Coronary angiography is planned within the next 24 hours.
Which antithrombotic therapy is most appropriate to start now, while he awaits angiography?
Aspirin plus parenteral anticoagulation (e.g., unfractionated heparin), with the P2Y12 inhibitor given once coronary anatomy is defined at angiography.
This patient has an NSTEMI with high-risk features (dynamic ST-segment depression, elevated troponin), so an early invasive strategy (angiography within 24 hours) is planned. Aspirin (162-325 mg loading dose) plus parenteral anticoagulation are recommended at presentation to limit thrombus propagation. Because angiography will occur within 24 hours, the P2Y12 inhibitor that completes DAPT is generally given once coronary anatomy is known (e.g., at PCI, when ticagrelor or prasugrel is preferred): the 2025 ACC/AHA guideline supports upstream clopidogrel or ticagrelor only as a weak (Class 2b) option when angiography is expected to be delayed >24 hours, and the 2023 ESC guideline recommends against routine pretreatment when early invasive management is planned. This avoids excess bleeding risk if the patient needs CABG, as outlined in the second and third bets.
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Etiology / Epidemiology
Caused by coronary artery plaque rupture with subtotal occlusion. Primary risk factors: HTN, DM, smoking, dyslipidemia.
Clinical Manifestations
Substernal levine sign chest pain without ST-elevation. Elevated cardiac troponins are the diagnostic hallmark.
Diagnosis
Serial troponins and ECG showing ST-depression or T-wave inversion. Coronary angiography is the reference standard for defining coronary anatomy.
Treatment
Aspirin plus heparin (parenteral anticoagulation), with a P2Y12 inhibitor completing dual antiplatelet therapy (DAPT); its timing is tied to angiography. Avoid nitrates in right ventricular infarction.
Prognosis
Risk stratified by TIMI score. Monitor for arrhythmias and heart failure post-MI.
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Epidemiology & Etiology
NSTEMI occurs when a coronary plaque ruptures, causing partial vessel occlusion or distal embolization. Diabetes mellitus is a major risk factor, often presenting with silent ischemia. Incidence increases with age, male sex, and family history of premature CAD.
Pertinent Anatomy
Involves the epicardial coronary arteries (LAD, LCx, or RCA). Ischemia typically affects the subendocardium, which is the most vulnerable layer to hypoperfusion due to high wall tension.
Pathophysiology
Plaque rupture leads to platelet aggregation and thrombus formation. Unlike STEMI, the vessel remains patent enough to prevent transmural necrosis. This results in myocardial ischemia without full-thickness injury, manifesting as elevated biomarkers without ST-segment elevation.
Clinical Manifestations
Patients present with retrosternal chest pressure radiating to the jaw or left arm, often described as the Levine sign. Red flags include diaphoresis, syncope, or new-onset S3 gallop. Symptoms often occur at rest and are more persistent than in stable angina.
Diagnosis
Diagnosis requires elevated cardiac troponin I or T above the 99th percentile upper reference limit, with a rise and/or fall. ECG may show ST-segment depression or T-wave inversion. Coronary angiography is the reference standard for identifying the culprit lesion.
Treatment
Initial management includes aspirin (162-325 mg loading dose), parenteral anticoagulation, and a P2Y12 inhibitor, which is typically given once coronary anatomy is known when angiography is planned within 24 hours (ticagrelor preferred, or prasugrel once PCI is planned; clopidogrel if these cannot be used). Administer unfractionated heparin or enoxaparin for anticoagulation. Avoid early beta-blockers in patients with signs of heart failure or bradycardia. Use nitroglycerin for pain, but avoid in patients taking PDE-5 inhibitors.
Prognosis
Long-term outcomes depend on left ventricular ejection fraction (LVEF). Major complications include ventricular arrhythmias and mechanical complications like papillary muscle rupture. Patients should receive high-intensity statin therapy and lifestyle modification.
Differential Diagnosis
Aortic dissection: tearing chest pain radiating to the back
Pulmonary embolism: pleuritic pain with tachycardia/hypoxia
Pericarditis: positional pain relieved by leaning forward
GERD: burning pain relieved by antacids
Stable angina: pain predictable with exertion, relieved by rest
Go deeper
Elevated low-density lipoprotein (LDL) cholesterol directly infiltrates the arterial wall, causing atherosclerotic plaque formation and cardiovascular disease, dictating that LDL should be lowered as aggressively as possible.
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