Exercise Training-Induced Repolarization Abnormalities Masquerading as Congenital Long QT Syndrome

Area of Science:

• Cardiology
• Sports Medicine
• Genetics

Background:

• Diagnosis of long QT syndrome (LQTS) can be challenging, with occasional errors in identifying affected individuals.
• Athletes practicing sports who showed repolarization abnormalities were observed to be misdiagnosed.
• This observation prompted a study to investigate LQTS diagnosis in athletes.

Purpose of the Study:

• To investigate the diagnostic accuracy of LQTS in athletes presenting with ECG abnormalities.
• To differentiate between congenital LQTS and other causes of repolarization abnormalities in athletes.
• To assess the impact of detraining and physical activity resumption on ECG findings in athletes.

Main Methods:

• Focused on athletes referred for suspected LQTS due to ECG abnormalities during mandatory sports medical visits.
• Subjects underwent standard LQTS diagnostic procedures: resting and ambulatory ECG, exercise stress test, and genetic screening.
• Analysis included ECG parameters, genetic testing results, and clinical follow-up after detraining and retraining.

Main Results:

• Of 199 athletes with repolarization abnormalities, 121 were diagnosed with LQTS based on ECG and genotyping.
• 78 genotype-negative subjects showed normalization of ECG abnormalities after detraining, with recurrence upon retraining.
• These 33 individuals were considered not affected by congenital LQTS, highlighting a potential acquired form.

Conclusions:

• Suspected LQTS in athletes based on ECG abnormalities requires careful consideration.
• A significant proportion of genotype-negative athletes normalize ECGs after detraining, suggesting acquired LQTS.
• Diagnostic errors can be avoided by considering detraining effects and distinguishing congenital from acquired LQTS.