Channelopathies: Brugada syndrome, long QT syndrome, short QT syndrome, and CPVT.

In approximately 10-20% of all sudden deaths, no structural cardiac abnormalities can be identified. Important potential causes of sudden cardiac deaths in the absence of heart disease are primary electrical diseases such as Brugada syndrome, long QT syndrome (LQTS), short QT syndrome (SQTS), and catecholaminergic polymorphic ventricular tachyarrhythmias (CPVT). The resting ECG and the ECG under exercise are pivotal for the diagnosis of ion channel diseases. Molecular genetic screening can reveal underlying mutations in a variable degree among the cardiac ion channel diseases in up to 70% (LQTS) and may identify individuals with incomplete penetration of the disease. In patients with primary electrical diseases, specific clinical triggers for arrhythmic events such as syncope or sudden cardiac death have been identified including exercise, strenuous activity, auditory stimuli, or increased vagal tone. Young, otherwise healthy individuals are likely to be involved in sports activity. Therefore, special attention has to be given to advise these patients. Competitive sports and vigorous exercise are contraindications in almost all patients. Even recreational exercise may have to be avoided in phenotypically overt patients or silent gene carriers depending on the underlying disease.