[Risk factors for sudden cardiac death related to the long QT syndrome].
BACKGROUND: Long QT syndrome is a rare condition. The syndrome is characterised by a prolonged QT-interval corrected for heart rate (QTc). The typical clinical presentation is the occurrence of syncope or cardiac arrest in young and otherwise healthy individuals. Cardiac events can be precipitated by environmental factors and use of certain drugs. The purpose of the present study is to provide guidelines regarding risk factors that may worsen the syndrome, based on available literature. MATERIAL AND METHODS: PubMed was searched for all literature in English from 1966 through 2004 on the Long QT syndrome. The articles and their literature references were examined. Additional information was achieved from experienced colleagues and from some key sites on the internet. RESULTS: The symptoms of the Long QT syndrome are tachycardia, syncope or cardiac arrest, often related to psychological or physical stress in young, usually healthy individuals. The syndrome can be inherited or acquired and is commonly caused by mutations in the potassium channel or by lack of inactivation of the sodium channels. The most common causes of acquired conditions are electrolyte abnormalities, intracranial disease, dietary deficiencies, myocardial infarction, dilated cardiomyopathy, mitral valve prolapse, bradycardia, severe malnutrition among anorexic patients and the use of medication. INTERPRETATION: It is important to have knowledge about the Long QT Syndrome. The treatment is primarily to remove potential risk factors and medically to give beta-blockers or insert pacemakers or cardiac defibrillators.