Screening with an ECG is aimed at identifying people with cardiomyopathies or electrical disorders of the heart. In answer to the question, electrical abnormalities can be excluded with a one-off ECG, provided the patient has no symptoms. However, the situation is quite different with the cardiomyopathies.
Let me give you the example of hypertrophic cardiomyopathy. Hypertrophic cardiomyopathy is a hereditary disorder that is characterised by abnormal thickening of the heart muscle. That thickening of the heart muscle isn't there at birth and it usually develops during the pubertal spurt. So if we perform an ECG at the age of 13 or 14, we may not find any abnormality but by the time the individual is 17 or 18, the pathology may be rife and may be very easy to identify. So therefore, we cannot necessarily exclude with certainty that an individual will not develop hypertrophic cardiomyopathy just because the ECG was completely normal at the age of 14. We would suggest that such individuals undergo annual ECGs until they've completed their pubertal spurt.
The situation with arrhythmogenic right ventricular cardiomyopathy is even more different. This cardiomyopathy is relatively novel and we still don't fully understand the natural history of the condition. That is to say, that if someone's got a normal ECG at the age of 16, does that mean they'll never develop arrhythmogenic right ventricular cardiomyopathy? The answer to that question is we don't know; so what we recommend is five yearly screening, post puberty in anybody that's got a family history of arrhythmogenic right ventricular cardiomyopathy or who has symptoms that suggest that they may have an underlying cardiac disorder.
Just because someone has a normal ECG and has been reassured post puberty, does not mean that they will never ever develop a cardiac abnormality in the future. So the key is to be very vigilant about symptoms that suggest there may be a cardiac problem developing such as chest pain during exertion, breathlessness that is disproportionate to the amount of exercise being performed, palpitation, dizziness during exercise, a blackout during exercise or a blackout without warning. Should any individual that's been screened by us and been given the all clear ever develop these symptoms, they must come back for further investigations.