27.JAN.2017 6 MIN READ | 6 MIN READ

Even the fittest athletes can succumb to heart disease.

Dr Leslie Tay, an interventional cardiologist at Mount Elizabeth Hospital, advises on reducing the risk of sudden cardiac arrest during sports.

It is always sad and shocking to hear the tragic news of relatively young athletes passing away unexpectedly while competing in endurance events. Although such deaths are uncommon (1-in-50000 to 1-in-8000 participants a year), even one death is one too many, especially if they can be prevented.

What is a sudden cardiac arrest?

As its name suggests, a sudden cardiac arrest occurs when the heart unexpectedly and suddenly stops beating. At the same time, blood supply to the brain and vital organs ceases. If left without treatment, the person is dead within minutes.

When does a sudden cardiac arrest strike?

A sudden cardiac arrest usually occurs when one reaches the peak of his game. This is the time when athletes push themselves further towards the finishing line, resulting in an adrenaline rush that can trigger irregular heartbeats (dubbed 'deadly heart rhythm'). This, in turn, leads to sudden cardiac arrest, especially in people with pre-existing heart diseases.

What can cause a sudden cardiac arrest?

There are over 20 possible conditions linked to sudden cardiac arrest during a sporting or endurance event. In participants above 35 years old, sudden cardiac arrests are frequently associated with coronary artery disease and heart attacks. In the younger participants, however, inherited cardiac abnormalities are usually responsible, and the most common condition is hypertrophic cardiomyopathy (HCM).

HCM occurs when a part of the heart muscle becomes abnormally thick and disrupts the blood flow. Additionally, the heart muscle cells responsible for regular heartbeats also become highly disorganised. These 2 factors combined increases the risk of developing a deadly heart rhythm.

When a person with HCM is exhausted and dehydrated (during an intense race, for example), the body loses blood due to dehydration and the heart struggles to supply sufficient blood to the body. Stable and sufficient blood supply ensures the body receives enough oxygen for survival but when that supply is disrupted, a deadly heart rhythm develops and that ultimately leads to sudden cardiac arrest.

Recognising the symptoms

Many cardiac arrest victims do not experience any symptoms but many of the conditions that cause cardiac arrest presents themselves with ominous symptoms such as breathlessness, chest pain, heart palpitation, fainting spells or loss of consciousness.

How to prepare for an endurance event

Being well prepared to take part in a race or obstacle course does not only mean training your physical strength. It is also equally important to go for a heart screening to make sure you are fit to race.

If you have any pre-existing illnesses that you feel may put you at risk, you should speak to your doctor before committing to the race.

Although not foolproof, pre-participation screening is key to identifying individuals at risk of sudden cardiac arrest. Medical tests are conducted to screen for patients with underlying heart diseases, which may put them at increased risk of sudden cardiac arrest. If a heart disease is detected, patients can move forward with treatment.

Pre-participation screening does not just apply to professional athletes and those running marathons but also to those looking to start in any strenuous exercise programme.

What to do before an endurance event

Adequate training
Begin a training programme appropriate for the activity you are participating in and allow time for a gradual build-up of intensity. As a guide, marathon runners often begin training at least 6 months ahead of the race, and even earlier if you are a beginner.

You may be prepared to sweat it out during your race but also remember to fuel your body with fluid to avoid dehydration. As your body goes through various stages of dehydration throughout the race, your body loses blood too. To prevent a lack of oxygen supply (and eventual death by cardiac arrest), do remember to fuel your body with water throughout the race.

Listen to your body
It might be difficult but learn to read signs of your body. Your body is the best indicator of your limits and learning to recognise when your body is exhausted can prevent you from overexerting yourself.

Consult your doctor
Do not race if you experience breathlessness, chest pain, heart palpitation, or feel faint while exercising. As a precaution, consult your doctor on whether you should avoid racing if you have any history of diabetes mellitus, hypertension, hyperlipidaemia, or a family history of sudden cardiac death.

Remember, an important part of being well prepared is to go for a heart screening. Don't take your health for granted and assume you are surely fit to race. Heart screening may reduce the risk of sudden cardiac arrest.

Tay Leslie
Mount Elizabeth Hospital

Dr Leslie Tay is a cardiologist practising at Mount Elizabeth Novena Hospital, Singapore.