Perspective:

The authors address an important issue of accurate diagnosis of LQTS, as such diagnosis may have profound consequences on the lives of patients suspected of having the life-threatening condition. Overdiagnosis of LQTS brings a host of undesirable effects, such as inappropriate lifelong medication, sports disqualification, unnecessary implantable cardioverter-defibrillator (ICD) implantation, inappropriate ICD shocks, etc. It is notable that >1 of every 6 patients who arrive with a diagnosis of LQTS at the authors’ institution are eventually found not to have the diagnosis! The authors group factors associated with an incorrect diagnosis of LQTS into four domains: clinical, diagnostic, genetic, and family history. There are many reasons for temporary QT prolongation. One prominent instance of QT prolongation occurs early after vasovagal syncope due to dynamic changes in the autonomic tone. It is critical that the clinical history is consistent with an arrhythmogenic type of syncope, and that QT prolongation is documented on >1 electrocardiogram. Judicious use of genetic testing may mitigate the erroneous diagnosis of LQTS, as many variants of unknown significance skew toward misdiagnosis. Finally, it is key to perform a thorough multigenerational family history and accurate QT measurement excluding the U wave. Once a patient is given the ominous misdiagnosis, it may be difficult to rescind.