Long QT Syndrome

Long QT Syndrome is a disorder of the heart's electrical system. The QT interval is measured on the electrocardiogram and reflects the time it takes for the heart to recover electrically from each heartbeat. The cause of long QT syndrome is often due to an underlying genetic abnormality and is therefore an inherited heart disorder which means it can run in families. Sometimes the QT prolongation occurs because of medication or other cardiac conditions.

People with long QT syndrome can develop a chaotic, fast heart rhythm called torsades de pointe a type of ventricular tachycardia. This heart rhythm can lead to fainting or seizures. In some instances, a prolonged episode of this chaotic heart rhythm can lead to ventricular fibrillation and sudden death. The risk of life-threatening events is related to the degree of QT prolongation, gender, and type of gene mutation.

Signs and Symptoms

  • Syncope
  • Fainting
  • Seizures
  • Sudden death
  • Fainting, loss of consciousness


Treatment may include medication, avoidance of any QT prolonging drugs, lifestyle modification, and in some case, an implantable cardioverter defibrillator (ICD) may be recommended.

Risk Factors

Risk factors include a family history of sudden death, or family members with a diagnosis of long QT syndrome.