Treat the underlying cause of strokes, heart attacks

Many of us are aware that cardiovascular disease - disease of the heart or blood vessels - is the leading cause of death in Singapore. According to statistics from the Ministry of Health, it kills over 5,500 people a year. It is estimated that almost 23.6 million people will die from cardiovascular disease every year by 2030, and that the largest increase in number of deaths will occur in the South-East Asia Region.

While people may be familiar with terms such as “heart disease”, “stroke” and even “cardiovascular disease”, many are not aware of a condition named "atherothrombosis" which is the underlying cause of most heart attacks, strokes, and peripheral arterial disease.

What is atherothrombosis?

Simply put, atherothrombosis refers to the formation of a blood clot in an artery. When a clot forms in an artery leading to the heart, it results in a heart attack. When a clot forms in an artery leading to the brain, it results in a stroke.

These blood clots occur when plaques, caused by the buildup of fatty materials along the arterial wall, rupture and damage the wall of the artery. Cells in the blood known as platelets respond to this by forming a clot to seal the damaged area. In an already narrowed artery, such blood clots can further reduce or completely block the flow of blood in the artery. The loss of oxygen rich blood to various parts of the body can cause serious damage to the brain or heart, depending on where the clot is located.

What are the implications of atherothrombosis?

Atherothrombosis may lead to one or more of the following consequences:

Heart attack: When a blood clot occurs in an artery that supplies blood to the heart muscle, blood flow is severely reduced or completely blocked. This reduces the amount of oxygen available for use by the heart. It can result in irreversible damage to the heart muscle with potentially life-threatening consequences.

Ischaemic stroke: Atherothrombosis in an artery either in or leading to the brain is one cause of an ischaemic stroke. About 85 per cent of strokes are ischaemic strokes. When a blockage of an artery in the brain lasts less than 24 hours and produces no lasting brain damage or symptoms, it is known as a transient ischaemic attack (TIA). TIAs suggest a high risk of further strokes.

Peripheral arterial disease: When blood flow is restricted by narrowing arteries in the legs, pain or discomfort may occur in the buttocks, thighs or calves, usually after walking a certain distance. This pain, called intermittent claudication, generally goes away with rest. Some individuals also complain that their feet are cold. However, two thirds of people with peripheral arterial disease do not have any noticeable symptoms.

Who is at risk?

Who is at risk of atherothrombosis?

Various age, genetic and lifestyle factors determine an individual’s risk of atherothrombosis.

Recognised risk factors for atherothrombosis include:

  • Previous history of atherothrombotic events (such as heart attack or stroke);
  • Diabetes
    - Approximately 1 out of 11 of Singaporeans have diabetes
  • High levels of fats in the blood such as cholesterol or triglycerides
    - Almost 20 per cent of Singaporean adults aged have high cholesterol
  • High blood pressure
    - 1 in 4 Singaporean adults have high blood pressure 
  • Smoking
    - More than one in ten Singaporean adults smoke cigarettes
  • Advancing age (65 years for males, 70 years for females)
  • Lack of exercise

If you have one of the recognised risk factors listed above, you are more likely to develop atherothrombosis. Those who have more than one risk factor are at an even higher risk of suffering a heart attack or stroke.

Other health dangers

Are there any other health dangers associated with atherothrombosis?

If a person suffers from atherothrombosis in one part of the body, they are at increased risk of further problems in the same, or another location. For example, a person suffering from peripheral arterial disease is at a higher risk of suffering a heart attack or stroke. Similarly, people with a history of stroke are at a higher risk of suffering a heart attack.

Treatment for atherothrombosis

Patients who have acute coronary syndrome (that is, they have already suffered an atherothrombotic event) will usually be prescribed antiplatelet therapy. This is usually a combination of aspirin and Clopidogrel, taken as two separate tablets each day. However studies have found that there is often a decline in compliance with taking both medications over a 12 month period.

The latest in antiplatelet therapy combines aspirin and Clopidogrel in a single tablet called CoPlavix. By reducing the number of pills the patient has to take each day, as well as lowering monthly medicine costs, patient compliance is improved, which in turn, improves the outcome of treatment.

Being on antiplatelet therapy does not mean that lifestyle changes are no longer necessary. Instead, modifications to one’s diet and activity levels should be regarded as the first line of defense against atherothrombosis.

Lifestyle modifications include quitting smoking, increasing exercise levels and adopting a low-fat, high-fibre diet.

Aim to exercise regularly, at moderate intensity, for at least 30 minutes a day for most days of the week. Regular exercise not only lowers high blood pressure, high blood sugar levels and high cholesterol levels, it also reduces the “stickiness” of blood.

A high-fibre, low-fat and low-cholesterol diet is also beneficial in reducing blood pressure, cholesterol and obesity, which in turn, lowers one’s risk of atherothrombosis.

Alcohol intake should also be limited to no more than two servings per day, while those who smoke should stop smoking completely. Studies have shown that any amount of smoking can increase the risk of stroke and heart attack by 2 or 3 times.

Research has shown that aggressive modification of risk factors in high-risk individuals can lower risk of atherothrombosis by as much as 50 per cent over five years.

This article was contributed by National Heart Centre Singapore (NHCS) and is part of a series on heart health.

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