Persistent ECG abnormalities in heart transplant recipients should prompt consideration of acquired channelopathies from the allograft, which can be confirmed via genetic testing.
BACKGROUND: Congenital long QT syndrome (LQTS) is rare but significant, as it carries a risk for ventricular arrhythmias and sudden cardiac death. Its diagnosis can be made clinically by serial ECGs, ambulatory ECG monitoring, and exercise stress testing; however, genetic testing is confirmatory in the majority of cases. METHODS: Here, we describe a rare case of phenotype-positive LQTS in a 6-year-old heart transplant recipient, confirmed 5 years after transplantation to be genotype-positive and thus "acquired" from the transplanted heart. RESULTS: Recognition of a persistently prolonged QTc interval on the recipient's serial ECGs led to ambulatory ECG monitoring and exercise stress testing-both of which were suspicious for LQTS. Ultimately, genetic evaluation and cardiac biopsy were obtained and resulted positive for a KCNQ1 pathogenic variant associated with Type 1 LQTS. CONCLUSION: Recognition of persistent, otherwise unexplained, ECG abnormalities can prompt genetic analysis of the allograft, leading to the potential life-saving diagnosis of a channelopathy.
Barresi et al. (2025) studied this question.