The Relationship between Thyroid Hormone Levels and Corrected QT Interval and QT Dispersion in Non-Diabetic Hemodialysis Patients

Abstract

Background: Cardiovascular disease and sudden cardiac death are common in hemodialysis patients. These cardiac complications are often associated with prolonged QTc interval (QTc) and QTc dispersion (QTcd). Subclinical hypothyroidism (SH) can alter autonomic modulation of heart rate and cause increased inhomogeneity of ventricular recovery time. We aimed to evaluate the relationship between thyroid hormone levels and QTc and QTcd in non-diabetic hemodialysis patients. Methods: We enrolled 29 non-diabetic hemodialysis patients without thyroid disease. After each hemodialysis session, a 12-lead ECG was recorded. Before each hemodialysis session, routine laboratory tests and measurement of thyroid hormone levels were performed. Patients were divided into 2 groups according to QTc (group 1 QTc < 430 ms, group 2 QTc ≥ 430 ms). We examined the relationship between QTc or QTcd and thyroid hormone in the respective groups and then compared the results from the 2 groups. Results: The mean age was 54.06 ± 14.72 years and the mean s of QTc and QTcd were 433.82 ± 22.03 ms, 59.10 ± 28.29 ms, respectively. Homocysteine levels were significant higher in group 2 than group 1 (p < 0.05) and QTcd w as comparable between groups. In group 1, QTc and QTcd were not significant correlated with TSH, T3, fT4 and biochemical parameters. In group 2, QTc was significant positively correlated with TSH (p < 0.05) and QTcd was not significant correlated with thyroid hormone levels. Conclusion: The results of this study showed that TSH is associated with prolonged QTc interval and hyperhomocysteinemia in non- diabetic hemodialysis patients. Moreover, we suggest that SH may be associated with prolonged QTc in non-diabetic hemodialysis patients. However, further studies are required to elucidate the role of the L-thyroxine doses and TSH target levels in hemodialysis patients.