Coronary artery disease (CAD), also known as ischaemic heart disease, occurs when the arteries that supply blood to the heart muscle (the coronary arteries) become hardened and narrowed. The arteries harden and narrow due to build-up of fatty deposits called plaque on their inner walls. The hardening of the artery walls is known as arteriosclerosis, while the build-up of plaque is known as atherosclerosis.

As the plaque increases in size, the insides of the coronary arteries get narrower and less blood can flow through them. Eventually, blood flow to the heart muscle is reduced and can cause chest pain (angina). A sudden, complete blockage can lead to a heart attack.

Many people with this disease are not aware they have it, as it develops slowly and silently over decades. It can go virtually unnoticed until it produces a heart attack.

What is Coronary Artery Disease? (Video)

Coronary artery disease varies in signs, symptoms and in severity. You may have no symptoms, otherwise referred to as silent ischaemia, where you do not have any symptoms although blood supply to your heart may be restricted.

You may also experience the following symptoms when you have coronary artery disease:

• Shortness of breath or breathlessness on exertion or when lying down: Occurs when the heart fails due to damage of heart muscles
• Decreased effort tolerance
• Pain in the neck, jaw, throat, upper abdomen or back
• Chest pain (angina) on exertion with or without radiation to the left arm: Usually brought about by physical or emotional stress. It feels like a heavy weight on your chest.
• Severe chest discomfort lasting more than 10 to 20 minutes, which may be due to a heart attack.
• Heart attack: Caused by a blood clot or rupture in a narrowed coronary artery. The part of the heart muscle fed by that artery dies. Pain from a heart attack is often described as a crushing pain and may feel similar to angina, but lasts longer.

Should you have severe chest discomfort, call an ambulance to bring you to the nearest hospital.

You can prevent or slow down coronary artery disease by improving the health of your heart and blood vessels. Here are some heart healthy activities:

• Exercise at least 150 minutes a week, with moderate intensity exercise
• Get six to eight hours of sleep daily
• Take two servings of fruits and three servings of vegetables daily
• Achieve and maintain a healthy BMI (Body Mass Index). The healthy range for Asians is from 18.5 to 22.9 kg/m².
• Stop or not start on smoking
  
  

For more information on heart health activities and nutrition guide, visit our 'Guide for Patients with Coronary Atherosclerosis' here.

Causes

Coronary artery disease is caused by atherosclerosis or hardening of the arteries due to old age. In atherosclerosis, plaque build-up in the arteries is made up of fat, cholesterol, calcium, and other substances from the blood.

Plaque build-up in the arteries often begins in childhood. Over time, plaque build-up in the coronary arteries can:

• Narrow the arteries, reducing the amount of blood and oxygen reaching the heart muscles
• Block the arteries completely which stops the flow of blood to the heart muscle
• Cause blood clots to form which can block the arteries that supply blood to the heart muscle.
  
  

Risk Factors

The risk factors that can contribute to coronary artery disease include:

• Diabetes mellitus
• High blood pressure
  
• High cholesterol
• Obesity
• Sedentary lifestyle and a lack of physical activity
• Smoking
  

Diagnosis normally starts with a physical examination by a doctor, assessing your medical history and further investigative tests. Investigative tests generally include:

• Functional Testing: Either a stress echocardiogram (dobutamine stress echocardiogram or exercise stress echocardiogram) or a nuclear stress test, to detect whether your heart responds abnormally to stress.
• Coronary Angiography: A fine tube being threaded through your arm or leg artery to evaluate for blockages in your heart arteries. Coronary stents or balloons may be inserted into the heart arteries if there are significant blockages detected.
  
  

Other specific routine tests recommended may include:

• Electrocardiogram (ECG)
• Exercise Stress Test
• Echocardiogram
  
  

It is recommended to first slow down coronary artery disease by improving the health of your heart and blood vessels, through lifestyle changes. Making lifestyle choices to control the risk factors for coronary artery disease is the best long-term measure.

Drugs and surgical techniques can open up narrowed coronary arteries. Optimal medical therapy such as aspirin (blood thinners), beta blockers (cardiac protective) and statins (cholesterol lowering medications) is given to all patients with coronary artery disease.

While many people are able to manage this disease with lifestyle changes and medications, others with severe coronary artery disease may need coronary angioplasty or surgery. There are various procedures to improve coronary blood flow (revascularisation):

• Percutaneous Coronary Intervention (PCI): A common treatment for severe blockage of the coronary arteries, it is also known as coronary or balloon angioplasty / percutaneous transluminal coronary angioplasty (PTCA) with coronary stent placement.
  
  
  
  In PTCA, a small balloon or stent is used to help keep the part of the artery that is blocked open. The latest option within PTCA is the use of drug-eluting stents, which are stents covered with a drug, which supposedly has been shown to reduce the rate of re-narrowing of the arteries. If percutaneous coronary intervention does not widen the artery or if complications occur, you may need coronary artery bypass surgery.
  
  
• Coronary Artery Bypass Surgery: This is an open heart surgery where a new route is created for blood to go around a blocked part of a coronary artery to supply your heart with enough blood to relieve chest pain.