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Overt hyperthyroidism is associated with increased dispersion of ventricular repolarization: a case-control study
Maksymilian Kłosowicz1,2, Magdalena Urbańczuk3, Aleksandra Burbelka1,2
1Department of Normal and Clinical Anatomy, Faculty of Medicine, Medical College, University of Rzeszów, Rzeszów, Poland.
Frontiers in Endocrinology
|July 22, 2026
Summary
Overt hyperthyroidism is linked to increased ventricular repolarization heterogeneity, indicated by elevated electrocardiogram (ECG) dispersion parameters. These findings suggest electrophysiological changes but do not confirm an increased arrhythmic risk.
Area of Science:
- Cardiology
- Endocrinology
- Electrophysiology
Background:
- Overt hyperthyroidism is associated with significant cardiovascular risks, including arrhythmias and heart failure.
- While standard ECG abnormalities are known, advanced markers of ventricular repolarization heterogeneity in hyperthyroidism are less understood.
Purpose of the Study:
- To investigate electrocardiogram (ECG)-derived ventricular repolarization dispersion parameters as potential markers in overt hyperthyroidism.
- To assess differences in repolarization heterogeneity between patients with overt hyperthyroidism and healthy controls.
Main Methods:
- A retrospective case-control study involving 97 participants (55 overt hyperthyroidism, 42 controls).
- Six ECG repolarization dispersion parameters were measured: QT dispersion (QTd), Bazett-corrected QT dispersion (QTcBd), Fridericia-corrected QT dispersion (QTcFd), JT dispersion (JTd), Fridericia-corrected JT dispersion (JTcFd), and Tpeak-Tend dispersion (Tp-ed).
- Statistical analyses included group comparisons, correlation, ROC analysis, and multivariable modeling.
Main Results:
- All six measured dispersion parameters were significantly elevated in patients with overt hyperthyroidism compared to controls (p < 0.001).
- JTcFd and QTcBd demonstrated the strongest discriminatory performance (AUC 0.813 and 0.804, respectively).
- Tpeak-Tend dispersion (Tp-ed) was independently associated with overt hyperthyroidism in multivariable analysis, with weak, non-significant correlations observed between thyroid hormone levels and dispersion indices.
Conclusions:
- Overt hyperthyroidism is associated with increased ventricular repolarization heterogeneity, evidenced by altered ECG repolarization parameters.
- These findings indicate underlying electrophysiological changes in overt hyperthyroidism.
- The precise clinical implications for arrhythmic risk require further investigation as arrhythmic outcomes were not assessed.
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