Symptoms such as syncope and chest pain, especially if they are accompanied by palpitations or occur with exercise in any combination, require cardiac evaluation before adolescent athletes are allowed to return to the sports field. Some life-threatening conditions will likely be associated with a family history of HCM or LQTS, but the family history may not be discovered at the first medical visit. A family history of CPVT, for example, is hard to elicit unless this diagnosis has already been established in an affected family member. The keys will be the timing of symptoms and the documentation of arrhythmia with exercise. The ECG at baseline in CPVT may be deceptively normal. Hypertrophic cardiomyopathy is progressive, so evaluation during early childhood may be negative. Long QT syndrome may not always result in an abnormal ECG, even in genetically positive individuals. A high index of suspicion is needed to make these diagnoses, especially if the family history is not available.