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Dear Doctor: I have a relative who died of sudden adult death syndrome. Is it a good idea for me to have tests done

Sudden adult syndrome or Sads is the term used for sudden cardiac death in an apparently fit and healthy young person.

It can be caused by a number of different heart conditions, some of which can be inherited. Heart rhythm abnormalities (arrhythmias) such as "Long QT Syndrome" and cardiomyopathy (heart muscle disease) are common causes of Sads.

In Long QT syndrome, the recharging of the electrical system after each heartbeat is longer than normal. This can result in a very fast, abnormal heart rhythm which can cause sudden loss of consciousness or, in some cases, sudden death. Symptoms usually begin in teenage years, but can also occur in newborns or appear as late as middle age.

The majority of conditions that can cause sudden cardiac death appear to be worsened by exercise. The person feels faint or passes out during exercise or when experiencing intense emotions such as fear. But it can also occur when asleep or on arousal from sleep. In one in three cases where death occurs , the person appears quite fit and healthy, with no symptoms at all before cardiac arrest happens.

Should I be tested for this condition?

If there have been any suspicious or sudden deaths in close family members under 35, including cot death, or if you have symptoms of chest pain (exercise-related), palpitations, shortness of breath, prolonged dizziness or fainting/blackouts, it is important that you are tested to find out if you have the same medical condition. Tests include an ECG, which looks at the electrical conduction pathways around the heart. The other is an echocardiogram, which looks at the structure and size of the chambers of the heart and its muscle thickness. Both tests are painless and non-invasive and take 15-20 minutes.

Your GP can refer you for these investigations.

What if nothing is found on these tests. Should I get tested again in a few years ?

If results are normal and you have no symptoms you are at low risk. The people at highest risk are those who have symptoms, or already had a cardiac arrest, or have significant abnormalities on their tests. But if you are young and have been tested, and your doctor thinks you are not affected, you should have another review in the future. ECG changes can become more obvious with age in children and young adults. But there is little evidence that repeated testing of relatives of someone who has died of Sads is helpful unless you develop new symptoms, or the technology for detecting these conditions improves.