Long QT Syndrome — diagnostic dilemmas.

Long QT syndrome is an increasingly recognised cause of sudden death in both adults and children. The mode of presentation is extremely variable, but of note 40% of cases' initial presentation is a cardiac arrest. It is an autosomal dominant condition, caused by mutations on several genes encoding ion channels. Only 50-60% of known families have an identifiable mutation in a long QT gene. This is of significance since thorough cardiac assessment misses up to 40% of those at risk. In Cardiff we have reviewed 7 families with long QT syndrome. Long QT syndrome is often misdiagnosed as faints, panic attacks or epilepsy. In our experience 4/8(50%) of the index cases died, and only one of these was diagnosed before death. Two were misdiagnosed as epileptic, one as panic attacks and one missed due to concurrent congenital heart disease. Diagnosis in the index case resulted in identification of 37 at risk 1st degree relatives. Potential misdiagnoses in the wider family include 6 cases of epilepsy, 3 panic attacks, 1 brain haemorrhage,1 myocardial infarct (age 27 years) and 1 unexplained cardiac arrest. Identification of further at risk family members was complicated by lack of stored DNA from the index cases. Doctors and pathologists need to be aware of the diagnosis and suggest family investigation. [ABSTRACT FROM AUTHOR]