• Clinical science

Coronary artery disease (Coronary heart disease…)

Summary

Coronary artery disease (CAD) is an ischemic heart disease that is most commonly caused by atherosclerosis and the subsequent reduction of blood supply to the myocardium, resulting in a mismatch between myocardial oxygen supply and demand. Acute retrosternal chest pain (angina) is the cardinal symptom of CAD. Other symptoms include dyspnea, dizziness, anxiety, and nausea. Severe ischemia may lead to myocardial infarction (MI). CAD is diagnosed using cardiac stress testing and/or coronary catheterization. Management of CAD involves primary and secondary prevention of atherosclerosis (e.g., weight reduction), antianginal treatment (e.g., beta blockers) and, in severe cases, revascularization (e.g., percutaneous transluminal coronary angioplasty).

This article provides a basic overview of coronary artery disease and stable angina. “Atherosclerosis” and “Acute coronary syndrome” (including myocardial infarction) are discussed in separate articles.

Definition

Epidemiology

  • CAD is the leading cause of death in the US and worldwide. [1]
  • The lifetime risk of coronary artery disease at age 50 is approx. 50% for men and 40% for women. [2]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

Pathophysiology

Plaque formation and coronary artery stenosis [3][4]

Myocardial oxygen supply-demand mismatch [5]

An increased heart rate reduces oxygen supply and increases oxygen demand.

Effect of vascular stenosis on resistance to blood flow [6]

  • The resistance to blood flow within the coronary arteries is calculated using the Poiseuille equation: R = 8Lη/(πr4), where R = resistance to flow, L = length of the vessel, η = viscosity of blood, and r = radius of the vessel.
  • Provided the length of the vessel and viscosity of blood remain constant, the degree of resistance can be calculated using the simplified formula: R 1/r4

Vascular stenosis increases vascular resistance significantly. For example, a 50% reduction in radius results in a 16-fold increase in resistance: R ≈ 1/(0.5 x r)4 = [1/(0.5 x r)]4 = (2/r)4 = 16/r4.

Myocardial ischemia [5]

Coronary steal syndrome

Coronary steal syndrome should not be confused with coronary-subclavian steal syndrome.

Chronic ischemic heart disease

Clinical features

Angina

Angina is the cardinal symptom of CAD. Patients with CAD usually become symptomatic when the degree of coronary stenosis reaches ≥ 70%.

  • Typically retrosternal chest pain or pressure
    • Pain may radiate to the left arm, neck, jaw, epigastric region, or back.
    • Pain is not affected by body position or respiration.
    • No chest wall tenderness
    • May gradually increase in intensity
    • May present as gastrointestinal discomfort
    • May be absent, especially in geriatric and diabetic patients. [7]
  • Dyspnea
  • Dizzinesss, palpitations
  • Restlessness, anxiety
  • Autonomic symptoms (e.g., diaphoresis, nausea, vomiting, syncope)

Stable angina

  • Symptoms are reproducible/predictable
  • Symptoms often subside within minutes with rest or after administration of nitroglycerin
  • Common triggers include mental/physical stress or exposure to cold

Subtypes and variants

Vasospastic angina

Diagnostics

Patient history and physical exam

  • History of recurrent angina episodes
  • Signs of atherosclerotic vascular disease (e.g., absent foot pulses, carotid bruit)

Pretest probability of CAD

  • Clinical assessment of symptomatic patients to predict the probability of CAD, used to:
    • Help determine the need for further diagnostic tests
    • Guide the selection of best initial diagnostic test

Factors used to estimate the probability of CAD [12]

Probability of CAD [13] Clinical presentation Next diagnostic step

Low (< 10%)

  • No further diagnostic tests are recommended
Intermediate (10–90%)
High (> 90%)

Resting ECG

Cardiac stress test [14]

Provocation methods

Preparation

Findings in stress-induced ischemia [17]

  • Clinical findings
    • The following findings should prompt immediate interruption of stress testing:
  • ECG (detection method of choice)
  • Imaging: (echocardiography, myocardial perfusion imaging)
    • Used if the patient's resting ECG cannot be interpreted
    • Helps distinguish between reversible ischemia and irreversible ischemia
    • Echocardiography
      • To detect wall motion abnormalities
      • Simultaneous evaluation of ventricular size and functional parameters (e.g., EF) and detection of valvular disorders is possible.
    • Radionuclide myocardial perfusion imaging (PET or SPECT): to visualize perfusion [19]

Patients with new-onset chest pain, ST-depression, hypotension, or arrhythmias should undergo cardiac catheterization.

Cardiac catheterization

Additional tests

Differential diagnoses

See “Differential diagnosis of chest pain.”

The differential diagnoses listed here are not exhaustive.

Treatment

Approach [20]

Antianginal treatment [20]

Effects of drugs on MVO2 parameters
Parameter Beta blocker Nitrates Combination therapy

Blood pressure

Heart rate

↑ (reflectory)

Unchanged or slightly ↓
Inotropy ↑ (reflectory) Unchanged
Ejection time Unchanged
End-diastolic volume Unchanged or ↑ Unchanged or slightly ↓
MVO2 ↓↓

Revascularization

Prognosis

Prevention

Prevention of atherosclerosis

Special considerations in coronary artery disease [25][26]

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  • 20. Amsterdam EA, Wenger NK, Brindis RG, et al. 2014 AHA/ACC Guideline for the Management of Patients With Non–ST-Elevation Acute Coronary Syndromes: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2014; 130: pp. e344–e426. doi: 10.1161/CIR.0000000000000134.
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last updated 10/14/2020
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