Some 60-80 people under the age of 35 suffer sudden cardiac death (SCD) every year in Ireland, according to Dr Deirdre Ward, director of the Centre for Cardiovascular Risk in Younger Persons at Tallaght Hospital, Dublin.
SCD deaths can cause "pockets of hysteria" among the public, particularly after a spate of deaths, explains Ward.
Although SCD can affect elite athletes, most young people die unexpectedly during routine activities or even sleep.
SCD is relatively rare, she says. The risk of suffering SCD for those under 35 years of age is about one in 100,000.
Overall, 5,000 people of all ages die suddenly each year due to cardiac rhythm disturbance - also known as cardiac arrest, or sudden cardiac death.
The majority of these deaths are caused by the occurrence of sudden blockages in the arteries of the heart (heart attacks).
Cardiac death in young people is mostly due to heart muscle disease, electrical disorder (both of which are often inherited) or congenital heart disease.
If you have one of these conditions, engaging in competitive sport may double your risk.
However, for the majority of the population, avoiding exercise for fear of SCD will greatly increase their risk of developing coronary disease and heart attacks in later years.
Most of these conditions can be identified by relatively simple heart tests, according to Ward.
The biggest risk factor associated with SCD is a family history of sudden death from heart disease or unknown causes at a relatively young age.
Symptoms which may indicate the presence of heart disease include: chest discomfort or shortness of breath with exercise that limits your ability to perform exercise; unexplained blackouts, especially if they occur during exercise; and prolonged palpitations, especially if they cause you to suffer dizziness or blackouts.
Cardiac evaluation is available for those at risk at local hospitals, or through either of the two specialist clinics based in Tallaght Hospital and the Mater Hospital.
Cardiac evaluation usually involves an ECG, an exercise test on a treadmill or bicycle, while your cardiac performance is monitored by an attached cardiac monitor, an echocardiogram (heart ultrasound) and a heart rhythm monitor for 24 hours.
Both of the specialist clinics are funded by charitable donations and are free.
The Centre for Cardiovascular Risk in Younger Persons operates from Tallaght Hospital (tel: 01-4143058), with a clinic in St James's Hospital and links to St Vincent's University Hospital.
The charity CRY Ireland (for information tel: 01-8395438) provides information and counselling services to families affected by SCD and funds the centre in Tallaght.
To contact the Family Heart Screening Clinic at the Mater Hospital, tel: 01-8034354.