The most common symptom of this disorder is recurrent fainting spells, often occurring during exercise or emotional excitement. Long QT syndrome can result from an inherited genetic defect in one of six genes or acquired through use of certain medications, stroke or other neurological disorders. The usual treatment for this disorder is beta-blocker drugs. There is a tremendous variation in the symptoms and effects of this disorder, Mason said. People may live to be 100 with this disorder, or it may cause death in infancy.
Many people never develop any symptoms while some have many episodes over many years.
Heart cells must expel potassium rapidly to recharge for the next heart beat. The inherited form results from changes in genes that code for proteins in the muscle cells of the heart. These proteins act as channels for potassium to leave the cell rapidly. In one of the inherited forms of long QT syndrome, potassium cannot leave through the channel quickly, so the muscle cells take longer to recharge, which lengthens the QT interval. Mason is now leading a international clinical trial funded by the National Institutes of Health, with participating medical centers at the University of Utah, University of Rochester, and in Pavia, Italy, to test if a simple therapy can control the cause of the disorder.