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Emergency and Acute Medicine – Acute Coronary Syndrome: Angina
Overview and Definitions
Angina pectoris refers to chest discomfort caused by an imbalance between myocardial oxygen supply and demand. It is a manifestation of acute coronary syndrome (ACS) and reflects underlying coronary artery disease or functional coronary abnormalities. Angina is commonly classified using the Canadian Cardiovascular Society (CCS) system.
Clinically, angina is categorized as stable or unstable. Stable angina is predictable, occurs with exertion, and resolves with rest or nitroglycerin. Unstable angina (UA) is characterized by new-onset symptoms, increasing frequency or severity, a lower threshold for pain, or symptoms occurring at rest, and is associated with a significantly increased risk of myocardial infarction and death.
Etiology and Risk Factors
Angina most often results from atherosclerotic narrowing of the coronary arteries. Major cardiac risk factors include advanced age, male sex, postmenopausal status in women, hypercholesterolemia, diabetes mellitus, hypertension, smoking, and family history of coronary disease.
Stable angina reflects chronic fixed coronary obstruction, whereas unstable angina usually results from acute plaque disruption and thrombosis. Other causes include coronary vasospasm (e.g., Prinzmetal angina, cocaine or amphetamine use), microvascular dysfunction, inflammatory arteritis (such as lupus, Takayasu arteritis, Kawasaki disease, or rheumatoid arthritis), anemia, elevated carboxyhemoglobin levels, and structural coronary abnormalities due to radiation, aneurysm, or ectasia.
Clinical Presentation
Patients typically describe substernal pressure, heaviness, tightness, burning, or squeezing chest pain that is poorly localized and visceral in nature. Pain may radiate to the neck, jaw, left shoulder, or arm. Anginal equivalents are common and include dyspnea, epigastric discomfort, diaphoresis, nausea or vomiting, weakness, abdominal pain, or syncope.
Symptoms are often precipitated by exertion, eating, cold exposure, or emotional stress and are usually relieved by rest or nitroglycerin. Pain is typically not positional or pleuritic and generally lasts more than a few minutes but less than 20 minutes. Relief with nitroglycerin alone is not diagnostic.
Women, older adults, patients with diabetes, and ethnic minorities frequently present with atypical symptoms and have worse outcomes due to delayed diagnosis.
Physical Examination
The physical exam is often normal. Some patients demonstrate the classic Levine sign—a clenched fist over the chest. Blood pressure may be elevated during pain episodes. Occasionally, exam findings include an S3 or S4 gallop, a new murmur from papillary muscle dysfunction, or diminished peripheral pulses.
Essential Emergency Evaluation
A 12-lead ECG should be obtained and interpreted within 10 minutes of arrival for any patient with possible cardiac ischemia. ECG is most useful for identifying acute myocardial infarction but is less sensitive for unstable angina. Comparison with prior ECGs is critical. If the initial ECG is normal or unchanged, serial ECGs every 10–30 minutes are recommended.
Findings suggestive of unstable angina include T-wave inversion, flattening, biphasic T-waves, or ≤1 mm ST-segment depression measured 80 ms after the J point. A single ECG is only about 60% sensitive for acute MI. Importantly, patients with normal or nonspecific ECGs still carry a measurable risk of MI and UA.
Laboratory and Imaging Studies
Cardiac biomarkers (troponin I or T, CK-MB) are not required for classic stable angina but should be obtained when MI is suspected. Low-level troponin elevations occur in fewer than half of patients with unstable angina and signify higher risk. Additional labs include hematocrit (to assess anemia), electrolytes, renal function, and coagulation studies.
Chest radiography is usually nonspecific but may show cardiomegaly, pulmonary edema, or alternative diagnoses such as pneumonia, pneumothorax, or aortic pathology.
Advanced imaging options include coronary CT angiography for low-risk patients without known coronary disease, bedside echocardiography to assess wall motion abnormalities or alternative causes of shock, and radionuclide perfusion imaging. Coronary angiography remains the diagnostic gold standard for coronary artery disease.
Differential Diagnosis
The differential for angina-like chest pain is broad and includes myocardial infarction, aortic dissection, pulmonary embolism, pericarditis, myocarditis, pneumothorax, pneumonia, esophageal spasm or reflux, peptic ulcer disease, biliary colic, musculoskeletal pain, anxiety or panic disorders, and herpes zoster, among others.
Prehospital and Initial ED Management
Early management includes IV access, cardiac monitoring, pulse oximetry, oxygen if hypoxic, and a 12-lead ECG when available. Aspirin should be administered promptly unless contraindicated, along with sublingual nitroglycerin for symptom relief.
Emergency Department Treatment
All patients with suspected cardiac ischemia should receive aspirin on arrival. Persistent pain after three doses of sublingual nitroglycerin raises concern for unstable angina or myocardial infarction. Additional measures include pain control, consideration of anticoagulation, and risk stratification.
First-line medications include aspirin, nitrates, and alternative antiplatelet agents (such as clopidogrel, prasugrel, or ticagrelor) in aspirin-allergic patients. Beta blockers may be considered for tachycardia or hypertension if no contraindications exist. Anticoagulation and glycoprotein IIb/IIIa inhibitors are generally reserved for higher-risk patients and typically initiated in consultation with cardiology.
Disposition and Follow-Up
Patients with unstable angina require hospital admission. Early invasive management with cardiac catheterization improves outcomes in those with elevated cardiac enzymes, persistent symptoms, or hemodynamic instability. Patients with unclear diagnoses often benefit from observation with serial ECGs, biomarkers, and stress testing.
Stable angina patients with negative evaluations may be discharged with close outpatient follow-up. All discharged patients should see their primary care physician or cardiologist within several days.
Clinical Pearls and Pitfalls
A careful history is the most important tool for distinguishing stable from unstable angina and noncardiac chest pain. An immediate ECG is mandatory for all patients with possible cardiac symptoms, and serial ECGs are essential when the initial tracing is nondiagnostic. A single set of negative cardiac enzymes does not exclude ACS. Maintain a low threshold for aggressive evaluation in women, older adults, diabetics, and patients with atypical presentations.
Overview and Definitions
Angina pectoris refers to chest discomfort caused by an imbalance between myocardial oxygen supply and demand. It is a manifestation of acute coronary syndrome (ACS) and reflects underlying coronary artery disease or functional coronary abnormalities. Angina is commonly classified using the Canadian Cardiovascular Society (CCS) system.
- Class I: No angina with ordinary physical activity
- Class II: Mild limitation of activity; angina with exertion such as climbing stairs or emotional stress
- Class III: Marked limitation of activity; angina with minimal exertion (walking 1–2 blocks or one flight of stairs)
- Class IV: Angina at rest or inability to perform any physical activity without symptoms
Clinically, angina is categorized as stable or unstable. Stable angina is predictable, occurs with exertion, and resolves with rest or nitroglycerin. Unstable angina (UA) is characterized by new-onset symptoms, increasing frequency or severity, a lower threshold for pain, or symptoms occurring at rest, and is associated with a significantly increased risk of myocardial infarction and death.
Etiology and Risk Factors
Angina most often results from atherosclerotic narrowing of the coronary arteries. Major cardiac risk factors include advanced age, male sex, postmenopausal status in women, hypercholesterolemia, diabetes mellitus, hypertension, smoking, and family history of coronary disease.
Stable angina reflects chronic fixed coronary obstruction, whereas unstable angina usually results from acute plaque disruption and thrombosis. Other causes include coronary vasospasm (e.g., Prinzmetal angina, cocaine or amphetamine use), microvascular dysfunction, inflammatory arteritis (such as lupus, Takayasu arteritis, Kawasaki disease, or rheumatoid arthritis), anemia, elevated carboxyhemoglobin levels, and structural coronary abnormalities due to radiation, aneurysm, or ectasia.
Clinical Presentation
Patients typically describe substernal pressure, heaviness, tightness, burning, or squeezing chest pain that is poorly localized and visceral in nature. Pain may radiate to the neck, jaw, left shoulder, or arm. Anginal equivalents are common and include dyspnea, epigastric discomfort, diaphoresis, nausea or vomiting, weakness, abdominal pain, or syncope.
Symptoms are often precipitated by exertion, eating, cold exposure, or emotional stress and are usually relieved by rest or nitroglycerin. Pain is typically not positional or pleuritic and generally lasts more than a few minutes but less than 20 minutes. Relief with nitroglycerin alone is not diagnostic.
Women, older adults, patients with diabetes, and ethnic minorities frequently present with atypical symptoms and have worse outcomes due to delayed diagnosis.
Physical Examination
The physical exam is often normal. Some patients demonstrate the classic Levine sign—a clenched fist over the chest. Blood pressure may be elevated during pain episodes. Occasionally, exam findings include an S3 or S4 gallop, a new murmur from papillary muscle dysfunction, or diminished peripheral pulses.
Essential Emergency Evaluation
A 12-lead ECG should be obtained and interpreted within 10 minutes of arrival for any patient with possible cardiac ischemia. ECG is most useful for identifying acute myocardial infarction but is less sensitive for unstable angina. Comparison with prior ECGs is critical. If the initial ECG is normal or unchanged, serial ECGs every 10–30 minutes are recommended.
Findings suggestive of unstable angina include T-wave inversion, flattening, biphasic T-waves, or ≤1 mm ST-segment depression measured 80 ms after the J point. A single ECG is only about 60% sensitive for acute MI. Importantly, patients with normal or nonspecific ECGs still carry a measurable risk of MI and UA.
Laboratory and Imaging Studies
Cardiac biomarkers (troponin I or T, CK-MB) are not required for classic stable angina but should be obtained when MI is suspected. Low-level troponin elevations occur in fewer than half of patients with unstable angina and signify higher risk. Additional labs include hematocrit (to assess anemia), electrolytes, renal function, and coagulation studies.
Chest radiography is usually nonspecific but may show cardiomegaly, pulmonary edema, or alternative diagnoses such as pneumonia, pneumothorax, or aortic pathology.
Advanced imaging options include coronary CT angiography for low-risk patients without known coronary disease, bedside echocardiography to assess wall motion abnormalities or alternative causes of shock, and radionuclide perfusion imaging. Coronary angiography remains the diagnostic gold standard for coronary artery disease.
Differential Diagnosis
The differential for angina-like chest pain is broad and includes myocardial infarction, aortic dissection, pulmonary embolism, pericarditis, myocarditis, pneumothorax, pneumonia, esophageal spasm or reflux, peptic ulcer disease, biliary colic, musculoskeletal pain, anxiety or panic disorders, and herpes zoster, among others.
Prehospital and Initial ED Management
Early management includes IV access, cardiac monitoring, pulse oximetry, oxygen if hypoxic, and a 12-lead ECG when available. Aspirin should be administered promptly unless contraindicated, along with sublingual nitroglycerin for symptom relief.
Emergency Department Treatment
All patients with suspected cardiac ischemia should receive aspirin on arrival. Persistent pain after three doses of sublingual nitroglycerin raises concern for unstable angina or myocardial infarction. Additional measures include pain control, consideration of anticoagulation, and risk stratification.
First-line medications include aspirin, nitrates, and alternative antiplatelet agents (such as clopidogrel, prasugrel, or ticagrelor) in aspirin-allergic patients. Beta blockers may be considered for tachycardia or hypertension if no contraindications exist. Anticoagulation and glycoprotein IIb/IIIa inhibitors are generally reserved for higher-risk patients and typically initiated in consultation with cardiology.
Disposition and Follow-Up
Patients with unstable angina require hospital admission. Early invasive management with cardiac catheterization improves outcomes in those with elevated cardiac enzymes, persistent symptoms, or hemodynamic instability. Patients with unclear diagnoses often benefit from observation with serial ECGs, biomarkers, and stress testing.
Stable angina patients with negative evaluations may be discharged with close outpatient follow-up. All discharged patients should see their primary care physician or cardiologist within several days.
Clinical Pearls and Pitfalls
A careful history is the most important tool for distinguishing stable from unstable angina and noncardiac chest pain. An immediate ECG is mandatory for all patients with possible cardiac symptoms, and serial ECGs are essential when the initial tracing is nondiagnostic. A single set of negative cardiac enzymes does not exclude ACS. Maintain a low threshold for aggressive evaluation in women, older adults, diabetics, and patients with atypical presentations.
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