Prevalence and diagnosis

About 25% of Western population develops signs or symptoms of atherosclerosis during their lifetime. Atherosclerosis typically begins in early adolescence, and is usually found in most major arteries, yet is asymptomatic and not detected by most diagnostic methods during life. According to United States data for the year 2004, for about 65% of men and 47% of women, the first symptom of atherosclerotic cardiovascular disease is heart attack or sudden cardiac death (death within one hour of onset of the symptom).

Most artery flow disrupting events occur at locations with less than 50% lumen narrowing (~20% stenosis is average). Cardiac stress testing, traditionally the most commonly performed non-invasive testing method for blood flow limitations, in general, detects only lumen narrowing of ~75% or greater, although some physicians claim that nuclear stress methods can detect as little as 50%.

Biomarker assays such as CRP and chitotriosidase in blood samples of individuals from risk groups may prove to be usefull detecting atherosclerosis at an early stage, to start treatment and diet and thereby prevent heart attack.

Pathology

Atherosclerosis typically begins with an injury to the inner wall of the artery, caused by high cholesterol, high blood sugar, toxins, infection, or smoking. In response to the injury, inflammation occurs, which causes further damage to the inside wall of the artery. Cholesterol is deposited at the site of the injury and the cholesterol is covered by a layer of scar tissue, produced by the smooth muscle cells that make up the wall of the artery.

The combination of cholesterol and scar tissue is called a plaque. The plaque may continue to grow on the inside of the vessel, reducing the space for blood to flow through the vessel. The plaque may also break away from the wall of the blood vessel, where it is carried further in the artery by the bloodstream. As the artery becomes smaller and smaller, eventually the plaque becomes stuck in the artery. This completely stops blood from flowing to the tissues supplied by the artery.

The effects of atherosclerosis differ depending upon which arteries in the body narrow and become clogged with plaque. If the arteries that bring oxygen-rich blood to the heart are affected, you may have coronary artery disease, chest pain, or a heart attack. If the arteries to the brain are affected, you may develop a transient ischemic attack (TIA) or a stroke. If the arteries in arms or legs are affected, you may develop peripheral artery disease. You may also develop a bulge in the artery wall (aneurysm).

Approximately 14 million Americans have CAD. Each year, 1.5 million individuals develop acute myocardial infarction (AMI), the most deadly presentation of CAD, and more than 0.5 million die.