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What Is Coronary Artery Disease? - Heart Health

Coronary Artery Disease is the narrowing of the specific blood vessels – the coronary arteries – that supply oxygen and other nutrients to the heart muscle. You’ll find that some people refer to this as ‘coronary heart disease’. But this term actually – and a bit confusingly – refers to more than just blockage of the coronary arteries. It also includes blockages to the arteries in the neck which increase the risk of stroke.

Either way, the same problem causes both which means someone with coronary artery disease also has an increased risk of stroke. The underlying problem is atherosclerosis - stiffening and thickening of the artery lining over many years with the build-up of what’s called plaque.

The build up of plaque is a complex process that can all start in childhood where LDL or ‘bad’ cholesterol is ‘dumped’ into the artery lining, the body’s defences – the immune system – reacts to this and the lining becomes inflamed and swollen (see ‘How atherosclerosis develops’) .

Post mortems of adolescents who’ve died of other causes often show quite marked atherosclerosis and unless our lifestyles are changed, coronary artery disease steadily and often silently progresses through our life, which is why heart disease is such a major killer.

Heart attacks occur when plaques rupture and blood clots form and break off, blocking the coronary artery. Angina is when the plaque builds up more steadily causing a narrowing which starves the heart muscle of oxygen when you exert yourself. Strokes are caused when plaque in the neck (carotid) arteries rupture and clots break off and land in and blocked brain arteries.

How atherosclerosis develops

Arteries are blood vessels which carry blood, which has picked up oxygen in the lungs, away from the heart. Blood in arteries moves faster than veins (which return blood to the heart and lungs) and is under more pressure and therefore more prone to damage. Understanding how atherosclerosis occurs helps you understand why changing your lifestyle helps to prevent heart disease.

The bad guy is LDL (low density lipoprotein) cholesterol which is raised when you eat saturated fats (the fat in meat and unmodified dairy products like butter and milk). LDL is balanced by the good guy, HDL (high density lipoprotein) cholesterol, which can remove free cholesterol from the arteries. HDL is lowered by smoking and raised (a good thing) by exercise, weight loss and modest amounts of alcohol.

While a bad diet raises LDL, it also does something else that’s not good for your arteries. It increases a highly toxic form of oxygen called free radicals. These free radicals react with LDL oxidising it – like rusting in fact. When this oxidised LDL in the blood comes in contact with the artery lining, it damages it, causing an immune response in which white blood cells attack the offending LDL molecules which are now inside the artery wall.

If there’s too little HDL around to mop things up, all this becomes ‘trapped’ in the artery walls, which in turn captures more oxidised cholesterol. This heightens the original immune response, which is then repeated. The build-up is called plaque. Eventually the immune reaction causes scarring - “fibrotic” changes - which harden the artery wall.

The swelling first bulges outward – that is, away from the central tube of the artery, or ‘lumen’. But eventually it squeezes inward, narrowing the lumen and restricting the flow of oxygenated blood through the artery.

Effects of atherosclerosis

Atherosclerosis can affect any artery in the body, causing different diseases depending on where those arteries are.

Specifically, its ill effects include:

  • Narrowing or stenosis of the arteries. Once it reaches a certain size, plaque can rupture, and blood clots form over to ‘heal’ it. Once healed, the clots shrink and harden. This successive shrinking and hardening causes what’s known as ‘stenosis’, or narrowing, of the affected arteries as well as those that surround them. This reduces blood flow and increases blood pressure. When the arteries concerned supply the heart muscle, this can cause chest pain and other symptoms on exertion - known as angina. If the narrowing completely blocks the artery then the muscle dies. That’s a heart attack. If this process occurs in the neck arteries then the result is stroke. And if it happens in the leg arteries, the result is pain in the calves when walking (claudication) and gangrene.
  • Heart attack or myocardial infarction. A¬s we’ve just seen, if a narrowing of a coronary artery completely blocks the artery over time, then the muscle dies. That’s a heart attack. But heart attacks can happen in another way. Sometimes, softer plaque in the coronary arteries ruptures but doesn’t heal over and narrow. Instead, a blood clot (thrombus) can form behind it, either slowing or completely blocking blood supply to the heart. This can lead to the damage or death of the affected areas within minutes, and if the damage is severe enough or in the wrong place, it can be fatal. Sudden death in younger people is thought sometimes to be due to these immature, softer plaques rupturing because they are unstable.
  • Aneurysm. Aneurysms occur when the part of the artery wall that’s been damaged by atherosclerosis becomes oversized, weak and balloons outward. This makes the artery more prone to rupture and bleeding, which can also be fatal. The most common place for such a dangerous aneurysm is the aorta at the place in the body where it passes down through the abdomen (abdominal aortic aneurysm).
  • Cerebrovascular disease. This occurs when atherosclerosis affects arteries that feed the brain. Ruptures and blockages that occur in these arteries cause strokes. When the brain arteries themselves are affected then the result can be what’s called vascular dementia.
  • Peripheral artery disease. This occurs when atherosclerosis affects arteries in the arms and, more commonly, legs. This causes pain – usually in the calves – when walking or climbing stairs, lack of mobility, or in the case of total narrowing of the arteries or clots, death of the affected tissues. In men, erectile dysfunction can be another sign of peripheral artery disease.


In its early and middle stages, coronary artery disease has few symptoms, if any at all. In its later stages, the most common symptom of coronary artery disease is angina. Angina is often referred to as chest pain but it is actually a group of symptoms. it’s also described by patients as chest discomfort, heaviness, tightness pressure, aching, burning, numbness, fullness or squeezing. Although these symptoms are most often felt in the chest, they can also be felt in the back, shoulders and arms, sometimes radiating into the neck or jaw.

In summary, the most common symptom of coronary artery disease is angina, described as:

  • Dull pain (often described as discomfort and can be mistaken for heart burn or indigestion)
  • Tightness, heaviness or feeling of pressure in the centre of your chest
  • A squeezing or choking sensation
  • Shortness of breath
  • Pain in the back, shoulders and/or arms, sometimes radiating into the neck or jaw.

Less common symptoms can include:

  • Fainting
  • Sweating
  • Heavy dragging feeling in one or both arms
  • Tooth pain on exertion.

Next: Understanding risk factors

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Last published: 31 October 2011

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This information has been developed and reviewed for Bupa by health professionals. To the best of their knowledge it is current and based on reputable sources of medical research. It should be used as a guide only and should not be relied upon as a substitute for professional medical or other health professional advice.

Bupa Australia Pty Ltd makes no warranties or representations regarding the completeness or accuracy of the information. Bupa Australia is not liable for any loss or damage you suffer arising out of the use of or reliance on the information. Except that which cannot be excluded by law. We recommend that you consult your doctor or other qualified health professional if you have questions or concerns about your health. For more details on how we produce our health content, visit the About our health information page.

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