Researchers at the Mayo Clinic have discovered the epinephrine QT stress test that can predict the long QT syndrome with an accuracy of about 75%.
The Long QT syndrome is a rare yet almost fatal, heart rhythm disorder occurring right from birth and affecting about one in every 3000 people in the United States. Its name comes from the elongated Qt interval seen in the electrocardiogram (ECG ) of such people with the disease.
If untreated, 50% of the people with symptoms of LQTS will die within 10 years of the first diagnosis of the disease.
However type 1 LQTS, a common subtype of the LQTS syndrome may go unrecognized because the patient's resting ECG could be normal. In the epinephrine QT stress test, a patient is medicated to stimulate the heart in such a way that it mimics exercise revealing concealed type 1 long QT syndrome with an accuracy of about 75%.
This in turn can be confirmed by a blood test for LQTS genetic testing.
147 individuals, ages 8-59, who been referred to Mayo Clinic's Long QT Syndrome Clinic during the period between 1999 and 2002 had an epinephrine QT stress test. A paradoxical lengthening of the QT interval was observed in 96%of these patients during infusion of the epinephrine.
These results could help physicians to recognize, evaluate and diagnose LQTS.
Although the treatment for LQTS patients can vary the options include medication or the implantation of a cardioverter defibrillator.