Updated: 4/2/2021

Angina

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Snapshot
  • A 70-year-old man presents to his primary care physician with recurrent, intermittent, sudden-onset chest pain and shortness of breath. He reports that he often tires easily climbing the stairs. Initially, he experienced chest pain with activity, but now it occurs throughout the day. Medical history is significant for hypertension and type II diabetes. An electrocardiogram demonstrates mild ST-segment depressions in V1-V2. Cardiac troponins are not elevated. (Unstable angina)
Introduction
  • Clinical definition
    • substernal chest discomfort secondary to myocardial ischemia; however, myocyte necrosis is not present
      • note that patient will likely report discomfort rather than pain
  • Epidemiology
    • risk factors
      • smoking
      • atherosclerosis
      • poor dietary habits
  • Pathogenesis
    • background
      • myocardial ischemia occurs when the heart's demand for oxygen exceeds oxygen supply
        • factors that increase the heart's demand for oxygen include
          • heart rate
          • contractility
          • systolic blood pressure
          • myocardial wall tension/stress
        • determinants of oxygen supply include
          • oxygen carrying capacity
          • unloading of oxygen from hemoglobin
          • coronary artery blood flow
            • coronary steal
              • when a vasodilatory agent causes worsening chest pain by shunting blood away from ischemic myocardium 
    • pathology
      • myocardial ischemia leads to acidosis, a ↓ ATP supply, and the release of chemical substances (e.g., adenosine)
        • sympathetic sensory neurons become activated and result in the perception of pain in a dermatomal distribution
          • e.g., chest, neck, jaw, and down the left (most commonly) arm
          • geriatric or diabetic patients may not experience chest discomfort or pain due to impaired sensory nerve conduction (e.g., diabetic neuropathy) or may present with atypical symptoms (such as GI pain, nausea, and vomiting)
            • obtain an ECG in all patients who could be presenting with atypical symptoms  
  • General work-up
    • Initial
      • EKG 
      • Cardiac biomarkers: troponin, CK, and/or CK-MB
      • CXR
    • Cardiac catheterization for definitive diagnosis for high-risk patients
      • locate and assess severity of the lesion(s) +/- treatment (i.e., stent)
    • Stress-testing
      • to evaluate simultaneously with EKG, echo, and radionuclide perfusion studies
        • for suspected stable angina, initial exercise stress EKG +/- echo is indicated in patients with no contraindications to exercise 
          • in patients with contraindications to exercise (e.g., physical disability), a pharmacologic stress test can be performed using dobutamine or adenosine
          • pharmacologic stress tests always combine EKG and echo to improve sensitivity
      • for patients with intermediate-risk (i.e., chest pain that develops with exertion, but is relieved with rest or nitroglycerin, CAD risk factors)
      • all antianginal medications (beta-blockers, nitrates, calcium channel blockers) should be held for 48 hours before a stress test
      • for pharmacological stress tests using adenosine or regadenoson, use of dipyridamole should be held for 48 hours and intake of caffeine held for 12 hours to minimize false negative findings of ischemia
    • Low risk patients with negative work-up can be discharged with reassurance 
      • young (<50 years of age), female, active, non-smoker, chest pain not associated with exertion
 
Types of Angina
Types Pathology
Clinical Presentation Comments
Stable angina 
  • Typically secondary to atherosclerosis
    • this impairs coronary perfusion in the setting of increased cardiac demand (e.g., exertion)
  • Chest pain that develops with exertion but relieves with rest or nitroglycerin 
  • Electrocardiogram
    • may demonstrate ST segment depressions
Unstable angina
  • Incomplete coronary artery occlusion by a thrombus
    • indicative of a ruptured plaque with subsequent clot formation
  • Chest pain that persists whether with decreasing physical activity or rest 
  • Electrocardiogram
    • may demonstrate ST segment depressions or T wave inversions
Prinzmetal angina
  • Coronary artery spasms 
  • Chest discomfort unrelated to physical activity and is episodic
  • Triggers
    • cocaine
    • alcohol
    • triptans
  • Electrocardiogram
    • appears similar to a STEMI
    • may demonstrate ST segment elevations with reciprocal ST depressions
  • Treatment
    • calcium channel blockers
    • smoking cessation
    • nitrates
 

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