Arrhythmias & electrophysiology
Prominent U-waves without QT prolongation in X-linked creatine transporter deficiency caused by SLC6A8 variants
Authors' conclusion
This study highlighted an atypical ventricular repolarization pattern in patients with CTD (prominent U-waves and biphasic T-waves) without QTc interval prolongation.
Study context
- Population
- Male patients with creatine transporter deficiency (CTD) with confirmed SLC6A8 pathogenic variants20 distinct SLC6A8 variants
- Participants
- 23 patients
- Outcome
- Cardiac phenotype (resting ECG, Holter, transthoracic echocardiography, biological analysis)
Methodological detailsprospective
- Prospective
Main finding
As reported in the abstract
Cardiac phenotype
- Prominent U-waves on resting electrocardiogram (ECG)
- 82.6%
- Prominent U-waves on ambulatory ECG
- 95%
- Biphasic T-waves on resting ECG
- 30.4%
- Biphasic T-waves on ambulatory ECG
- 90%
- QTc interval, U-waves excluded (median [IQR], ms); no patient with prolonged QTc
- 431 ms [411-443]
- Mildly elevated NT-proBNP without clinical or imaging abnormalities (patients)
- 2
Observational data: associations, not effects.
Original publication
Prominent U-waves without QT prolongation in X-linked creatine transporter deficiency caused by SLC6A8 variants. Heart Rhythm. Published 14 November 2025. doi:10.
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