Familial, metabolic and lifestyle risk factors for coronary disease
THE CONTEXT
Coronary artery disease risk reflects inherited susceptibility, smoking, blood pressure, lipid and glucose abnormalities, haemostatic factors and physical activity.
Familial susceptibility
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Atherosclerotic coronary artery disease (CAD) often* runs in families. A positive family history is common in early-onset disease, defined here as onset before 50 years in men and before 55 years in women.
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Compared with the general population, a monozygotic twin of an affected individual has an eightfold risk of dying from CAD, while a dizygotic twin has a fourfold risk. Shared genetic, environmental and lifestyle factors contribute.
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Common risk factors including hypertension, hyperlipidaemia and diabetes mellitus have polygenic inheritance.
Smoking, blood pressure and cholesterol
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Cigarette smoking is the most important modifiable CAD risk factor, with a particularly strong relationship in people younger than 70 years.
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Atherosclerosis incidence increases with systolic blood pressure, diastolic blood pressure and pulse pressure. Antihypertensive therapy reduces cardiovascular mortality, stroke and heart failure.
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Atherosclerosis risk increases with serum cholesterol. Lowering total and low-density lipoprotein cholesterol reduces cardiovascular events.
Diabetes and insulin resistance
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Diabetes mellitus, especially type 2, is a potent risk factor for all forms of atherosclerosis and is often associated with diffuse disease that is difficult to treat.
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Insulin resistance is described as normal glucose homeostasis with high insulin levels. It is associated with obesity and physical inactivity and is a CAD risk factor.
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Glucose intolerance contributes substantially to the high incidence of CAD in South Asian people and some other ethnic groups.
Haemostasis and exercise
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Platelet activation and high plasma fibrinogen are associated with increased coronary thrombosis risk. Antiphospholipid antibodies are associated with recurrent arterial thromboses.
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Regular exercise, such as brisk walking, cycling or swimming for 20 minutes two or three times weekly, has a protective effect.
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Physical inactivity roughly doubles CAD risk and is a major stroke risk factor.