Long QT syndrome, or LQTS, is an abnormality in the rhythm of your heartbeat. It causes fast, erratic and sometimes dangerous heartbeats, usually when you exercise or feel stressed. The term “long QT” comes from the pattern doctors see on an electrocardiogram
, or EKG, when you have the condition.
Half of all people who have LQTS have their first abnormal heart rhythm by the time they’re 12 years old. About 90 percent have an abnormal heart rhythm by age 40. For this reason, doctors advise family members of people who have LQTS to be tested for this disorder.
Occasionally, people acquire LQTS, meaning they develop it during their lifetime. Some medications – such as antibiotics, diuretics, and antihistamines – and other health conditions can cause acquired LQTS.
Health conditions that can cause acquired LQTS include severe diarrhea or vomiting, eating disorders such as anorexia nervosa and bulimia, and some thyroid disorders. These conditions lower the sodium or potassium levels in your blood, which can trigger long QT symptoms.
Most people, however, inherit LQTS.