Cardiac symptoms have a prominent position in hyperthyroidism. The cardiac and non-cardiac symptoms of hyperthyroidism may in part be related to an Increased sympathoadrenal activity. The thyroid hormones also exert a direct effect on the heart. in this study, we examined the value of OT dispersion as a simple non invasive predictive marker of hyperthyroidism. We examined 20 patients (age: 37±5.4 years, 16 female, 4 male) with hyperthyroidism and 22 age and sex- matched healthy subjects were selected to serve as the control group. Repolarisation dispersion parameters were calculated as the difference between maximal and minimal values of QT, QTc from 12-lead ECG recording at 25 mm/s. Comparisons were made using Student's t- test. QT and QTc dispersions were significantly longer in the patients with hyperthyroidism than in the control group. After treatment, QT and QTc dispersion intervals In the patients' group were not significantly different from these of the control group. in conclusion, striking increases in QT dispersion indicating regional inhomogenity of ventricular repolarization were noted in patients with hyperthyroidism. This new finding may suggest a possible explanation for the presence of ventricular arrhythmias in patients with hyperthyroidism.
Keywords: Hyperthyroidism, QT dispersion, Ventricular arrhythmias