Coronary Artery Disease
The dominant effect of coronary artery disease is the loss of oxygen and nutrients to myocardial tissue because of diminished coronary blood flow. Fatty fibrous plaques, calcium-plaque deposits, or combinations of both narrow the lumens of coronary arteries, reducing the volume of blood that can flow through them.
This disease is nearly epidemic in the Western world. Coronary artery disease is more prevalent in males, whites, and middle-aged and elderly people than in females or in people of other races before the age of 60. More than 50% of males age 60 or older show signs of coronary artery disease on autopsy. The peak incidence of clinical symptoms in females is between ages 60 and 70. (See Coronary artery disease in females, page 212.)
Causes
Atherosclerosis, the most common cause of coronary artery disease, has been linked to many risk factors. Some risk factors, such as the following, can’t be controlled.
Age — Atherosclerosis usually occurs after age 40.
Sex — Males are eight times more susceptible than are premenopausal females.
Heredity — A positive family history of coronary artery disease increases the risk.
Gender differencesCoronary artery disease in females
Coronary artery disease was once considered a “man’s disease”; however, it’s now recognized that cardiovascular disease is the leading cause of death in females. Age-adjusted mortality rates from heart disease in females are four to six times higher than the mortality rates from breast cancer. Female patients who present with myocardial infarction (MI) are more likely to be misdiagnosed and more likely to die of their first MI. Chest pain in perimenopausal females is often difficult to diagnose because it may present atypically. Shoulder or neck pain, nausea, fatigue, or dyspnea are more likely to signal MI in females than in males.
Exercise, hypertension treatment, smoking cessation, and aspirin therapy are effective measures for the primary prevention of coronary artery disease in females. The roles of lipid-lowering agents and hormone replacement therapy in primary prevention are being investigated.
However, the patient can modify other risk factors with good medical care and appropriate lifestyle changes:
Blood pressure — Systolic blood pressure that is greater than 160 mm Hg or diastolic blood pressure that is greater than 95 mm Hg increases the risk.
Serum cholesterol levels — Increased low density lipoprotein and decreased high density lipoprotein levels substantially heighten the risk.
Smoking — Cigarette smokers are twice as likely to have a myocardial infarction (MI) and four times as likely to experience sudden death. The risk dramatically drops within 1 year after smoking ceases.
Obesity — Added weight augments the risk of diabetes mellitus, hypertension, and elevated serum cholesterol levels.
Physical activity — Regular exercise reduces the risk.
Stress — Added stress or type A personality increases the risk.
Diabetes mellitus — Type 2, or late-onset, diabetes raises the risk, especially in females.
Uncommon causes of reduced coronary artery blood flow include dissecting aneurysms, infectious vasculitis, syphilis, and congenital defects in the coronary vascular system. Coronary artery spasms may also impede blood flow. (See Understanding coronary artery spasm.)
Complications
When a coronary artery goes into spasm or is occluded by plaques, blood flow to the myocardium supplied by that vessel decreases, causing angina pectoris. Failure to remedy the occlusion causes ischemia and, eventually, myocardial tissue infarction.
Assessment
The classic symptom of coronary artery disease is angina, the direct result of inadequate flow of oxygen to the myocardium. The patient usually describes it as a burning, squeezing, or crushing tightness in the substernal or precordial chest that may radiate to the left arm, neck, jaw, or shoulder blade. Typically, the patient clenches his fist over his chest or rubs his left arm when describing the pain. Nausea, vomiting, fainting, sweating, and cool extremities may accompany the tightness. Female patients often exhibit vague or atypical complaints, such as “not feeling well.”
Angina commonly occurs after physical exertion but may also follow emotional excitement, exposure to cold, or a large meal. Angina can also develop during sleep and may awaken the patient.
The patient’s history will suggest any pattern to the type and onset of pain. If the pain is predictable and relieved by rest or nitrates, it’s called stable angina. If it increases in frequency and duration and is more easily induced, it’s referred to as unstable or unpredictable angina. Unstable angina generally indicates extensive or worsening disease and, left untreated,
may progress to MI. An effort-induced pain that occurs with increasing frequency and with decreasing provocation is referred to as crescendo angina. If severe pain occurs at rest without provocation, it’s called variant or Prinzmetal’s angina.
may progress to MI. An effort-induced pain that occurs with increasing frequency and with decreasing provocation is referred to as crescendo angina. If severe pain occurs at rest without provocation, it’s called variant or Prinzmetal’s angina.
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