Acute Coronary Syndrome

New Onset Severe Angina

• Characterized by increasing angina frequency and duration in previously diagnosed angina patients

ECG Interpretation

• 12-lead ECG should be obtained within 10 minutes of ED arrival
• ST segment changes indicate acute cardiac ischemia
• ST segment changes (≥ 0.05 mV) or T-wave inversion in 2 or more contiguous leads are diagnostic criteria
• ECG provides information on infarct location and size
• Areas of infarction do not produce electrical activity
• T-wave changes are the first manifestation of acute coronary occlusion (ischemia)
• T-wave inversion occurs first, followed by ST segment changes
• ST segment depression indicates lengthening of repolarization (NSTE-ACS), suggesting non-fully occluded vessels
• ST segment elevation indicates injury from ischemia extending from subendocardial to subepicardial regions (transmural ischemia), suggesting fully occluded vessels and STEMI

Laboratory Tests

• Cardiac troponin is the preferred biomarker for cardiac injury
• Troponin levels do not rise until 6 hours post-MI
• Elevated troponin levels can last up to 10-14 days
• Creatine Kinase MB fraction (CK-MB) and myoglobin are less sensitive and not recommended for myocardial infarction diagnosis
• B-type natriuretic peptide (BNP) can be added to the diagnostic panel

Diagnosis

• No cardiac biomarkers: Unstable Angina
• Positive cardiac biomarkers: NSTEMI

Identify the signs and symptoms of new onset severe angina, including ECG changes and determining the location and size of infarction. Learn how to diagnose acute coronary syndrome.