Major Signs and Symptoms
If you have long QT syndrome (LQTS), you can have sudden and dangerous arrhythmias (abnormal heart rhythms). Signs and symptoms of LQTS-related arrhythmias often first occur during childhood and include:
- Unexplained fainting. This happens because the heart isn't pumping enough blood to the brain. Fainting may occur during physical or emotional stress. Fluttering feelings in the chest may occur before fainting.
- Unexplained drowning or near drowning. This may be due to fainting while swimming.
- Unexplained sudden cardiac arrest (SCA) or death. SCA is a condition in which the heart suddenly stops beating for no obvious reason. People who have SCA die within minutes unless they receive treatment. In about 1 out of 10 people who have LQTS, SCA or sudden death is the first sign of the disorder.
Other Signs and Symptoms
Often, people who have LQTS 3 develop an abnormal heart rhythm during sleep. This may cause noisy gasping while sleeping.
Silent Long QT Syndrome
Sometimes long QT syndrome doesn't cause any signs or symptoms. This is called silent LQTS. For this reason, doctors often advise family members of people who have LQTS to be tested for the disorder, even if they have no symptoms.
Medical and genetic tests may reveal whether these family members have LQTS and what type of the condition they have.