Long QT Syndrome
Long QT syndrome (LQTS) is a heart rhythm disorder in which the heart's electrical recovery is delayed, increasing risk of dangerous arrhythmias, fainting, and sudden death. It can be inherited or acquired from medications.
Quick Facts
- ICD-10: I45.81
- Inherited types: LQT1, LQT2, LQT3, others
- Risk: Sudden cardiac death
Symptoms
- Fainting (syncope), often triggered by exertion, emotion, or startle
- Seizures (sometimes due to brain hypoxia during arrhythmia)
- Sudden cardiac arrest
- Family history of unexplained sudden death
- Many people have no symptoms before a serious event
Causes
Inherited
Mutations in cardiac ion channel genes (most commonly KCNQ1, KCNH2, SCN5A).
Acquired
- Many medications (some antibiotics, antipsychotics, antiarrhythmics, antifungals, antidepressants — there is a long list)
- Electrolyte abnormalities (low potassium, magnesium, calcium)
- Severe bradycardia
Diagnosis
- ECG showing prolonged QT interval
- Exercise stress test
- Holter monitoring
- Genetic testing for inherited forms
Treatment
- Avoid QT-prolonging medications (list maintained at credibles.org)
- Correct electrolytes
- Beta-blockers for inherited LQTS
- Implantable cardioverter-defibrillator for high-risk patients
- Left cardiac sympathetic denervation in selected cases
- Family screening
Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about a medical condition. If you are experiencing a medical emergency, call your local emergency number immediately.
References
- Heart Rhythm Society. Long QT Syndrome Resources.