Long QT syndrome

Title

Not a rare disease

Summary Summary

Long QT syndrome is a disorder of the heart’s electrical activity that can cause sudden, uncontrollable, and irregular heartbeats (arrhythmia), which may lead to sudden death. Long QT syndrome can be detected by electrocardiogram (EKG). It can be caused by a variety of different gene mutations (changes). It can also be acquired (noninherited) and may be brought on by certain medicines and other medical conditions.^[1]

Last updated: 10/4/2013

Symptoms Symptoms

Signs and symptoms of the arrhythmias experienced by people with long QT syndrome includes unexplained fainting, seizures, drowning or near drowning, and sudden cardiac arrest or death.^[1] You can read more about these and other symptoms of long QT syndrome on the National Heart Lung and Blood Institute's Web site by clicking here.

Last updated: 10/4/2013

The Human Phenotype Ontology (HPO) provides the following list of features that have been reported in people with this condition. Much of the information in the HPO comes from Orphanet, a European rare disease database. If available, the list includes a rough estimate of how common a feature is (its frequency). Frequencies are based on a specific study and may not be representative of all studies. You can use the MedlinePlus Medical Dictionary for definitions of the terms below.

Signs and Symptoms	Approximate number of patients (when available)
Sensorineural hearing impairment	Very frequent (present in 80%-99% of cases)
Atrioventricular block	Frequent (present in 30%-79% of cases)
Abdominal situs inversus	Occasional (present in 5%-29% of cases)
Anemia	Occasional (present in 5%-29% of cases)

Last updated: 5/8/2017

Cause Cause

Acquired long QT syndrome can be caused by certain medicines and medical conditions. Some medications that cause long QT syndrome include antihistamines and decongestants, antibiotics, antidepressants, and cholesterol-lowering medicines. Examples of medical conditions that can cause long QT syndrome include excessive diarrhea or vomiting and certain thyroid disorders.^[1]

Inherited forms of long QT syndrome are caused by changes in genes that control the heart muscle’s electrical activity.^[1] Inherited long QT syndrome may be isolated (occur alone without other associated symptoms) or be due to a genetic syndrome, such as Romano-Ward syndrome, Jervell Lang-Nielsen syndrome, Anderson-Tawil syndrome, and Timothy syndrome.^[2]

Last updated: 10/4/2013

Diagnosis Diagnosis

Long QT syndrome is diagnosed on the basis of electrocardiographic (EKG) findings, clinical findings such as congenital deafness or unexplained fainting, and family history of long QT syndrome or sudden cardiac death. Genetic testing is often performed in families in whom the diagnosis of long QT syndrome has been made or is suspected on clinical grounds.

Last updated: 10/4/2013

Testing Resources

Orphanet lists international laboratories offering diagnostic testing for this condition.

Do you have updated information on this condition? Let us know.

Research Research

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

ClinicalTrials.gov lists trials that are studying or have studied Long QT syndrome. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.
Orphanet lists European clinical trials, research studies, and patient registries enrolling people with this condition.
The Research Portfolio Online Reporting Tool (RePORT) provides access to reports, data, and analyses of research activities at the National Institutes of Health (NIH), including information on NIH expenditures and the results of NIH-supported research. Although these projects may not conduct studies on humans, you may want to contact the investigators to learn more. To search for studies, enter the disease name in the "Text Search" box. Then click "Submit Query".

Organizations Organizations

Nonprofit support and advocacy groups bring together patients, families, medical professionals, and researchers. These groups often raise awareness, provide support, and develop patient-centered information. Many are the driving force behind research for better treatments and possible cures. They can direct people to research, resources, and services. Many groups also have experts who serve as medical advisors. Visit their website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Sudden Arrhythmia Death Syndromes Foundation
4527 S 2300 E, Suite 104
Salt Lake City, UT 84117-4448
Telephone: 801-272-3022
Website: http://www.sads.org

Do you know of an organization? Send us your suggestions.

Learn More Learn More

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

The KidsHealth Web site developed by the Nemours Foundation has an information page on arrhythmias. Click on KidsHealth to view the information page.
The Mayo Clinic has developed an information page on long QT syndrome. Click on the Mayo Clinic to view the information page.
The National Heart, Lung, and Blood Institute (NHLBI) has information on this topic. NHLBI is part of the National Institutes of Health and supports research, training, and education for the prevention and treatment of heart, lung, and blood diseases.

In-Depth Information

The Merck Manuals offers a detailed review article on Long QT syndrome. Click on Merck Manuals to view the article.
Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
MeSH® (Medical Subject Headings) is a terminology tool used by the National Library of Medicine. Click on the link to view information on this topic.
Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.

Videos/Presentations

Identification and Treatment of Sudden Death Conditions in Young Patients. A presentation by David Bradley, M.D., Director, Pediatric Heart Rhythm Service, CS Mott Children's Hospital. Assoicate Professor, Department of Pediatrics and Communicable Diseases, University of Michigan.

GARD Answers GARD Answers

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

I have long QT syndrome, as does many of my family members. Some of these family members have been found to carry a mutation in a long QT syndrome gene, others with the condition do not. How can this be? How can I learn more about genetic testing for this syndrome? Is attention deficit disorder and/or celiac diseases related to long QT syndrome? Is genetic testing for celiac disease available? See answer

Have a question? Contact a GARD Information Specialist.

References References

Long QT syndrome. National Heart Lung and Blood Institute. 2007; http://www.nhlbi.nih.gov/health/dci/Diseases/qt/qt_all.html. Accessed 12/17/2008.
Sovari AA, Kocheril AG, Assadi R Baas AS, Zareba W, Rosero S. Long QT syndrome. eMedicine. 2010; http://emedicine.medscape.com/article/157826-overview . Accessed 4/15/2011.

Do you know of a review article? Send us your suggestions.