Coronary Artery Disease and Stable Angina
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- Coronary artery disease (CAD) refers to the atherosclerotic narrowing of the epicardial coronary arteries. It may manifest insidiously as angina pectoris or as an acute coronary syndrome (ACS).
- Stable angina is a chest discomfort due to myocardial ischemia that is predictably reproducible at a certain level of exertion or emotional stress.
- The spectrum of ACS includes unstable angina (UA), non–ST elevation myocardial infarction (NSTEMI), and ST elevation myocardial infarction (STEMI). See chapters on ACS for further information.
- Typical angina: exhibits three classical characteristics: (i) substernal chest pressure, pressure or heaviness that may radiate to the jaw, back, or arms and generally lasts from 2 to 15 minutes; (ii) occurs at a certain level of myocardial oxygen demand from exertion, emotional stress, or increased sympathetic tone; and (iii) relieved with rest or sublingual nitroglycerin
- Atypical angina: exhibits two of the above typical characteristics
- Noncardiac chest pain: exhibits ≤1 of the above typical characteristics
- Anginal equivalent: Patients may present without chest discomfort but with nonspecific symptoms such as dyspnea, diaphoresis, fatigue, belching, nausea, light-headedness, or indigestion that occur with exertion or stress. Patients with diabetes mellitus, women, and the elderly may present with more atypical features as compared to the general population.
- UA: anginal symptoms that are new or more frequent, more severe or occurring with lessening degrees of myocardial demand; it is considered ACS but does not present with cardiac biomarker elevation. (See “Acute Coronary Syndromes: NSTE-ACS (Unstable Angina and NSTEMI)” chapter.)
- NSTEMI: elevation of cardiac biomarker (troponin) with either anginal symptoms, ischemic ECG changes other than ST elevation, or both. (See “Acute Coronary Syndromes: NSTE-ACS (Unstable Angina and NSTEMI)” chapter.)
- STEMI: presents with typical symptoms as mentioned above with ST elevations noted on ECG; generally caused by acute plaque rupture and complete obstruction of culprit vessel and may present prior to laboratory detection of troponin. (See “Acute Coronary Syndromes: STEMI” chapter.)
- Canadian Cardiovascular Society grading scale:
- Class I: Angina does not limit ordinary physical activity, occurring only with strenuous or prolonged exertion (7 to 8 metabolic equivalents [METs]).
- Class II: Angina causes slight limitation of ordinary activity. It occurs when walking rapidly, uphill, or >2 blocks; climbing >1 flight of stairs; or with emotional stress (5 to 6 METs).
- Class III: Angina causes marked limitation of ordinary physical activity. It occurs when walking 1 to 2 blocks or climbing one flight of stairs (3 to 4 METs).
- Class IV: Angina occurs with any physical activity and may occur at rest (1 to 2 METs).
- The elderly may present with atypical symptoms.
- Physical limitations may delay recognition of angina until it occurs with minimal exertion or at rest.
- Maintain a high degree of suspicion during evaluation of dyspnea and other nonspecific complaints.
- Geriatric patients may be very sensitive to the side effects of medications used to treat angina.
- CAD is the leading cause of death for adults both in the United States and worldwide.
- CAD is responsible for about 1 in every 3 deaths in the United States alone.
- The cost of CAD in the United States was $555 billion in 2016 and is expected to rise to $1.1 trillion by 2035.
- ~80% of CAD is preventable with a healthy lifestyle.
In the United States, the lifetime risk of a 40-year-old developing CAD is 49% for men and 32% for women.
In the United States, 28.4 million people carry a diagnosis of CAD, whereas 7.12 million have angina pectoris (1).
Etiology and Pathophysiology
- Anginal symptoms occur during times of myocardial ischemia caused by a mismatch between coronary perfusion and myocardial oxygen demand.
- Atherosclerotic narrowing of the coronary arteries is the most common etiology of angina, but it may also occur in those with significant aortic stenosis, pulmonary hypertension, hypertrophic cardiomyopathy, coronary spasm, or volume overload.
- Sensory nerves from the heart enter the spinal cord at levels C7–T4, causing diffuse referred pain/discomfort in the associated dermatomes.
- Traditional risk factors: hypertension, ↓ HDL, ↑ LDL, smoking, diabetes, premature CAD in first-degree relatives (men <55 years old; women <65 years old), age (>45 years for men; >55 years for women)
- Nontraditional risk factors: obesity, sedentary lifestyle, chronic inflammation, abnormal ankle-brachial indices, renal disease
- Smoking cessation
- Regular aerobic exercise program
- Weight loss for obese patients (goal BMI <25 kg/m2)
- BP control (goal <140/90 mm Hg; consider <130/80 mm Hg for those with 10-year ASCVD risk ≥ 10%) (2)[C]
- Diabetes management
- Statin therapy for those with diabetes age 40 to 75 years and those with 10-year risk ≥7.5–10% (recommendations vary)
- Low-dose aspirin may be considered in those with 10-year risk ≥10% and without aspirin-use risks.
Commonly Associated Conditions
Hyperlipidemia, peripheral vascular disease, cerebrovascular disease, hypertension, obesity, diabetes