Diagnosis and Treatment of Long QT Syndrome

Long QT syndrome is a genetic condition that affects the heart’s electrical system. About 1 in 2500 people in the United States have some form of Long QT syndrome, which can cause cardiac arrest if untreated.

Long QT syndrome is caused by a defect in the ion channels (potassium, sodium, calcium, or chloride) in the heart. An ion channel defect means the heart doesn’t recharge correctly, and the extra time the heart takes to recharge lengthens the QT interval. During the QT interval, the heart is vulnerable, and an extra beat can trigger a life-threatening irregular heart rhythm. There are many types of long QT syndrome depending on the specific ion channel affected, although the top three account for about 90% of long QT syndrome patients.

About half of patients with long QT syndrome never have symptoms. In those with symptoms, the most common is syncope (sudden loss of consciousness) due to an irregular heartbeat that can be triggered by physical exertion, emotional response, or a sudden loud noise. If the irregular rhythm persists, it may result in a seizure or disorientation and confusion, which may lead to a patient being misdiagnosed with epilepsy.

Diagnosing long QT syndrome can be challenging, as an ECG may not always show a prolonged QT interval. In addition, some medications—including certain antibiotics, neurological medications, and nausea medications—can cause a prolonged QT even in patients without long QT syndrome. Your Oklahoma Heart Hospital physician may use a series of tests to diagnose long QT syndrome, including multiple ECGs, echocardiogram, treadmill test, or a wearable Holter monitor to track the heart rhythm for several days.

Genetic screening can also help identify patients who are at risk of developing long QT syndrome. If a family member has been diagnosed with this condition or if your family history includes family members who died suddenly at less than 50 years of age, genetic testing can help assess your personal risk for long QT syndrome.

The first course of treatment is usually the use of prescription beta-blocker medications to prevent irregular heart rhythms. Other common treatment options include placement of an ICD (implantable cardioverter defibrillator) to prevent death from an irregular heart rhythm (sudden cardiac death) or a procedure to block some of the nerves to the heart to prevent the irregular rhythm from happening. These less common options are generally used only for patients whose long QT syndrome is not adequately controlled through medication.

If you have a family history of long QT syndrome or sudden unexplained death before the age of 50, contact the Oklahoma Heart Hospital today for more information or to schedule an appointment with one of our physicians.