The relationship between the TSH values and the Tpeak - Tend interval duration in hypothyroid patients receiving Levothyroxine treatment.

Introduction: Changes in thyroid hormone level can affect the cardiovascular system. The aim of this study was to show how the Tpeak -Tend (Tpe) interval, which is a new marker of ventricular arrythmia, is affected in patients who have become euthyroid following Levothyroxine treatment for hypothyroidism, as this has not been examined previously in literature.

Materials And Methods: This, cross-sectional study included a total of 119 females aged 18-45 years, separated into 3 groups as hypothyroid, euthyroid and control groups. For evaluation of the QTc and Tpe intervals, examination on precordial V5 lead was made of all the ECGs taken routinely on presentation of the patients.

Results: The Tpe and QTc intervals of the hypothyroid group were determined to be significantly prolonged compared to those of the euthyroid and control groups (p < 0.001) and the values of the euthyroid and control groups were similar. A positive correlation was determined between TSH levels and Tpe and QTc intervals. Tpe interval AUC = 0.801 (%95 CI: 0.719 - 0.884) was higher than that of QTc AUC = 0.689 (%95 CI: 0.591 - 0.786).

Conclusions: The Tpe duration was evaluated in respect of the risk of arrythmia in hypothyroid patients. In patients who had become euthyroid, the Tpe interval was found to be similar to that of healthy individuals and was more predictive than QTc. In the light of these findings it can be recommended that measurement of the Tpe interval should be preferred to QTc as a marker of the arrythmogenic effect in hypothyroid patients.