Sudden Cardiac Death: Are You at Risk?

Source: Article first appeared in "Know Your Man Inside Out" by SingHealth / Her World

Did you know?

Heart attacks are not confined to the old. Even young men can get a heart attack leading to sudden death.  80 per cent of all sudden cardiac death are related to coronary heart disease which, in most cases, can be prevented.

What causes young men to die suddenly?The most common cause is sudden cardiac death (SCD), of which 80 per cent is related to coronary artery disease (CAD) (see box below), with or without a heart attack.

Unfortunately, over half of sudden cardiac death victims have no prior symptoms. Some patients have chest pain, breathlessness or sweating. When these occur in a patient at risk of heart problems, treatment should always be sought immediately.

An SCD attack is not the same as a heart attack. SCD is caused by an abnormal heart rhythm due to an abnormal ‘electrical circuitry’ of the heart. A heart attack is caused by blockage of the arteries supplying blood to the heart. The subsequent damage to the heart muscle may or may not lead to an SCD attack. It is estimated that 1,000 Singaporeans die from SCD every year, about half of whom are below 60 years old.

Learn to recognise these symptoms

• Central or left-sided chest pain often associated with sweating, nausea or breathlessness. The pain is described as something weighing heavily on the chest and is usually brought about by physical or emotional stress. It usually goes away within minutes when the stressful activity is stopped.

• Shortness of breath. Because the heart muscles are damaged by the shortage of blood supply or from a heart attack, it can’t pump blood efficiently to meet the body’s needs.

• Discomfort on exertion, jaw tightness on exertion or after meals. These symptoms immediately subside on resting.

In anyone at high risk for heart disease (eg diabetics, high cholesterol, hypertension, strong family history of heart disease), any chest symptom, even atypical, should be investigated. Diagnosis is made with an electrocardiogram and blood tests.

Treatment may involve hospitalisation and ways to restore blood flow in the coronary artery (by angioplasty or thrombolysis).

If you are around...

1. Call the ambulance immediately. Early treatment increases survival rate.

2. Perform chest compression CPR. This will also improve the chances of survival.

Cardiac Artery Disease (CAD) CAD is a common type of heart disease where fatty deposits accumulate in the coronary artery and impede the blood flow. Reduced blood flow to the heart can cause chest pain (angina). A sudden, complete blockage can lead to a heart attack. Many people who have this form of heart disease are not aware they have it. CAD develops slowly and silently over decades. It can go virtually unnoticed until it produces a heart attack. You can prevent or slow down CAD by taking steps to improve your heart health. Drugs and surgical techniques can open up narrowed coronary arteries, but the best long-term solution is to make the right lifestyle choices.

Are You in the High-Risk Group?Age: Age increases a person’s susceptibility to heart disease. Gender: Men are three to five times more likely to have coronary heart disease than women. However, the risk for women increases after menopause. Five to 10 years after menopause, women have the same risk for coronary heart disease as men. Ethnicity: Compared with Chinese, South Asians (Indians, Sri Lankans, Pakistanis, etc) are three times more likely to suffer from coronary heart disease. Malays have double the risk compared with Chinese. Obesity: People who have excess body fat – especially located around the waist – are more prone to heart disease and stroke even if they have no other risk factors. Excess weight increases the strain on the heart. It also raises blood pressure, blood cholesterol and triglyceride levels, and lowers HDL, ("good" cholesterol levels). It is also associated with the development of diabetes mellitus. Family history: You can be at higher risk of heart disease if your immediate family members (parents, children, brothers and sisters) have a history of premature heart disease. Certain risk factors tend to run in some families. If there is a history of heart disease in your family, you should try very hard to control your other risk factors. "In general, adults should know their family history of heart disease or sudden death. They should know their cholesterol level and know if they have diabetes mellitus and abnormal blood sugar levels. If you have any high-risk factor, get your doctor’s advice on how to improve those risk factors, change your lifestyle and dietary habits, and embark on a safe exercise programme."  Dr Teo Wee Siong, Senior Consultant Cardiologist, National Heart Centre http://www.healthxchange.com.sg/healthyliving/SpecialFocus/Pages/Sudden-Cardiac-Death-Are-You-at-Risk.aspx?

Sudden Cardiac Death: Not So Random As It Looks

Source: Article by National Heart Centre Singapore (NHCS), Heart Health

It is estimated that 1000 Singaporeans die from sudden cardiac death (SCD) every year, about half of whom are below 60 years old.

Is sudden cardiac death the same as a heart attack?

"A sudden cardiac death, or SCD, is not a heart attack," said Dr Aaron Wong, Senior Consultant at the National Heart Centre Singapore (NHCS). "A SCD can be due to many causes but is usually caused by an abnormal heart rhythmdue to abnormal 'electrical circuit' of the heart. A heart attack is caused by blockages in the heart arteries supplying blood to the heart, causing a portion of the heart muscle to be damaged. Heart attack may lead to abnormal heart rhythm, and therefore SCD, but not always."

Unlike a heart attack, which has symptoms such as chest pains and breathlessness, SCD usually has no warning signs. The only way to treat a SCD is to set the rapid heartbeat back to its normal pace by delivering an electrical shock to the heart using a device called a defibrillator.

Patients at high risk of SCD may be advised by their doctors to have an Implantable Cardiac Defibrillator (ICD)implanted. The ICD is a pocket-sized device which detects abnormal heart beats or rhythm and sends an electric current to the heart. This electric current shocks the heart and helps to reset the heart rhythm like a mini-defibrillator.

The most common cause

The most common cause of SCD is a sudden onset of abnormal heart rhythm. This is usually due to a fast but chaotic heart rhythm called ventricular fibrillation (VF) or tachycardia (VT). An extremely slow heart rate may cause SCD as well but usually presents with prior symptoms of giddiness or fainting episodes.


In a patient with VF (a form of cardiac arrest), the heart beats 400 to 500 beats per minute and the normal rhythmic contractions of the lower chambers of the heart stop. When this happens, blood and oxygen are not pumped to the rest of the body and within seconds, the brain becomes starved of oxygen and the person loses consciousness. Without immediate treatment, the brain will cease to function and the person can die within minutes.

Who is likely to suffer from sudden cardiac death?

SCD does not randomly occur in people. Almost 75 per cent of all SCD patients show signs of a previous heart attack and 80 per cent of them have signs of coronary artery disease (CAD).


It has also been found that people who have high blood pressure, high cholesterol, diabetes mellitus, or a family history of CAD are at risk of developing CAD which in turn could lead to SCD.


According to Dr Ching Chi Keong, Consultant, Department of Cardiology at NHCS, a typical SCD patient is likely to be male, more than 35 years old and has a family history of early heart attack. There is also a higher incidence amongst South Asians.


For those who are younger than 35 years old, risk factors include:

• a family history of sudden deaths or unexplained drownings
• recurrent chest pain and/or fainting episodes during physical exertion and
• known heart disease, especially hypertrophic cardiomyopathy.

Risk factors of SCD 

Coronary artery disease (CAD)

• SCD can occur during a heart attack where the damaged heart muscle induces an abnormal heart rhythm or there is a sudden loss of heart pumping function due to massive damage to the heart muscle. The latter is usually not sudden but presents initially with symptoms of difficulty in breathing.
• Dr Wong advises, "Patients who have CAD (e.g. previous angina, heart attack, angioplasty or bypass surgery) should control their risk factors for CAD and stop smoking. Some medications have also been proven to reduce the progression of CAD, the risk of heart attack and heart failure but may have to be taken on a long term basis. Patients should not stop or reduce their medications dosage without consulting their doctors."

Poor heart function or heart failure

• Poor heart function is usually caused by repeated injury to the heart muscle (heart attacks) that leads to scarring and subsequent loss of muscle contraction function.
• Poor heart function can also be due to disease of the heart muscle (known as cardiomyopathy) due to an inherited heart muscle disease or virus infection.
• SCD is one of the most common mode of death in patients with heart failure. Patients with heart failure should be on long-term medications that have been shown to improve symptoms and prolong life expectancy. Patients with severely impaired heart function may benefit from implanting an ICD to reduce the chance of dying from SCD.

Strong family history
Some heart diseases, including CAD, cardiomyopathy and some heart electrical disorders are hereditary.

• The most common inherited risk factor is high cholesterol.
• Extremely high cholesterol can lead to CAD and heart attack at an early age. A person whose parents or sibling had CAD at a young age or high cholesterol should have his/her cholesterol checked regularly. Aggressive control of cholesterol levels can reduce the chance of developing CAD and therefore SCD.
• Hypertrophic cardiomyopathy (HCM)
• An abnormal thickening and arrangement of the heart muscle cells can cause VF or VT leading to SCD, especially during exertion. Certain types of HCM are prone to SCD and a person with HCM who has close family members who passed away due to SCD should have an ICD implanted.
• Arrhythmogenic right ventricular dysplasia (ARVD)
• A structurally abnormal right ventricle is also an inherited disorder. An ICD is often required in these patients.
• Dilated cardiomyopathy
• Features a dilated heart with poor heart function. The condition can also be caused by a virus infection or in some cases, is related to pregnancy.

Electrical disorders of the heart

• Some electrical disorders of the heart can lead to SCD and occasionally can be picked up during routine ECG. Many of these disorders are also inherited, and a strong family history of SCD is important.
• One of these disorders (known as the Wolff-Parkinson-White Syndrome) is caused by an extra nerve connecting the heart chambers, which can cause an 'electrical short-circuit' in the heart, resulting in a rapid heartbeat. This condition is now easily treatable with catheter ablation, a procedure where a thin tube (catheter) is advanced into the heart via a vein (usually from the leg/groin), to deliver a burst of radiofrequency energy to burn off this abnormal nerve or pathway.
• Another type of electrical disorders that can cause SCD is due to abnormalities in the heart muscle cell membrane (e.g. Brugada's and Long QT Syndromes).
• They frequently present in young, apparently healthy individuals with no known heart problems, although some abnormalities can often be seen in the ECG on careful examination. In many, the first presentation is usually SCD. Frequent fainting episodes or even a diagnosis of epilepsy may accompany such conditions. For these patients, the ICD is the only alternative to prevent SCD.

Awareness of your risk factors is important. "If you are more than 35 years old, do adopt a healthy lifestyle. Screen yourself for risk factors of CAD (e.g. diabetes, high cholesterol) and stop smoking, especially if you have a family history of CAD. For those who are less than 35 years old, learn to recognise the above symptoms and go for a medical check up for assessment", says Dr Ching.

What to do if you witness a sudden cardiac death

In the event a person collapses from SCD, the key to survival is early defibrillation. It has been found that each minute of delay before defibrillation reduces survival by about 10 per cent. To help a person who has collapsed from SCD, the following steps have proven to be vital.

1. Call the ambulance.
2. Perform cardiopulmonary resuscitation (CPR).
3. Use the automated external defibrillator (AED), if available.

http://www.healthxchange.com.sg/healthyliving/SpecialFocus/Pages/Sudden-Cardiac-Death-Not-So-Random.aspx?