Article Impact Level: HIGH Data Quality: STRONG Summary of the Journal of the American College of Cardiology, 81(5), 477–486. https://doi.org/10.1016/j.jacc.2022.11.036 Sahej Bains et al
Points
- More than 1 of every six patients diagnosed with long QT syndrome in one quaternary medical clinic was later discovered not to have the condition.
- The key causes for long QT syndrome over-diagnosis included secluded QT prolongation, separated QTc prolongation, and sustained QTc interval secondary to vasovagal syncope.
- This physical examination appeared favorable for a version in one of the significant LQTS genetic makeup, a positive family history of unexpected cardiac death assumed to be irrelevant to LQTS, and an incorrect explanation of the QTc interval as a result of including the U wave.
Summary
The primary reason behind the trial was to detect diagnostic errors that cause long QT syndrome to be overdiagnosed. The researchers examined the participants’ electronic health care records for those who had been given an outside diagnosis of prolonged QT syndrome but were later discovered to have acceptable outcomes.
290 out of 1,841 participants were initially diagnosed with long QT syndrome, and around 16% had typical results. The main factors that led to long QT syndrome overdiagnosis included 15% QT prolongation, 30% QTc delay, and 30% long-term QTc interval secondary to vasovagal syncope.
The researchers came to the conclusion that vasovagal syncope is one of the most common reasons why long QT syndrome is misdiagnosed too often. This is a “pseudo”-positive hereditary test result for long QT syndrome-inducing genes, a family history of cardiac arrest, transient QT prolongation, and an incorrect explanation of the QTc interval due to the presence of the U wave.
The authors describe the critical problem of a proper prolonged QT syndrome assessment because such an evaluation could significantly impact people’s lives with the potentially fatal syndrome. Several unfavorable outcomes, including improper lifetime medications, disqualification from sporting events, and inappropriate implanted cardioverter-defibrillator installation, result from overdiagnosis of long QT syndrome.
Notably, at the researchers’ facility, more than 1 in every six individuals who are first given a long QT syndrome diagnosis are ultimately determined not to have the condition. The researchers classify the variables into medical, diagnostic, molecular, and family histories. These characteristics are linked to an inaccurate diagnosis of long QT syndrome. Temporary QT delays can occur for several different reasons. QT delay seems to be a frequent occurrence shortly after vasovagal syncope because of changes in autonomic tone. It is crucial that more than one ECG shows QT prolongation and that the patient history is compatible with an arrhythmogenic type of fainting.
The incorrect identification of long QT syndrome may be lessened with the careful application of genetic testing, as many variations of uncertain importance tend to be misdiagnosed. The importance of performing an exhaustive multigenerational family history and a precise QT assessment without the U-wave cannot be overstated. It could be challenging to retract the dire misdiagnosis once it has been given to a patient.
Link to the article: https://www.jacc.org/doi/10.1016/j.jacc.2022.10.019
References Bains, S., Neves, R., Bos, J. M., Giudicessi, J. R., MacIntyre, C., & Ackerman, M. J. (2023). Phenotypes of Overdiagnosed Long QT Syndrome. Journal of the American College of Cardiology, 81(5), 477–486. https://doi.org/10.1016/j.jacc.2022.11.036
