Ion Channel Diseases as a Cause of Sudden Cardiac Death in Young People: Aspects of Their Diagnosis, Treatment, and Pathogenesis.

Background: Sudden cardiac death (SCD) is the death of an apparently healthy person within one hour of the onset of symptoms, or within 24 hours of last being seen alive and well-with no evidence of an extra-cardiac cause. In autopsied cases, SCD is defined as the natural unexpected death of unknown or cardiac cause. The reported incidence figures for SCD vary widely.

Methods: This review is based on clinical registry studies, metaanalyses, randomized controlled trials, systematic reviews, and current guidelines that were retrieved by a selective search in PubMed employing the key words "channelopathy," "Brugada syndrome," "long QT syndrome," "catecholaminergic polymorphic ventricular tachycardia," "short QT syndrome," and "early repolarization."

Results: Approximately 18% of cases of SCD in young persons are associated with cardiac channelopathy. The most common ion channel diseases affecting the heart are long QT syndrome and Brugada syndrome. The diagnosis is established by specific ECG abnormalities in the absence of structural heart disease. These can be unmasked by various maneuvers, e.g., the administration of sodium-channel blockers in Brugada syndrome. Imaging studies such as echocardiography, coronary angiography, and computed tomography are used to rule out structural heart disease and coro nary artery disease. Long-term ECG and risk stratification scores can be useful aids to therapeutic decision-making. For some of these diseases, it is advisable for the patient to avoid particular triggers of ECG changes and cardiac arrhythmias in his or her everyday life. The near relatives of persons with congenital ion channel diseases should undergo clinical and gen etic screening to protect them from SCD.

Conclusion: The affected families should be investigated systematically so that appropriate diagnoses and treatments can be established.