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Evaluation of QT dispersion and Tp‐e interval in children with subclinical hypothyroidism
Author(s) -
Akın Alper,
Unal Edip,
Yıldırım Ruken,
Ture Mehmet,
Balık Hasan,
Haspolat Yusuf Kenan
Publication year - 2018
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/pace.13286
Subject(s) - medicine , qt interval , subclinical infection , confidence interval , cardiology , triiodothyronine , electrocardiography , hormone , endocrinology
Background Studies on adults have shown increased dispersion of QT and corrected QT (QTc), peak‐to‐end interval of the T wave (Tp‐e), Tp‐e/QT ratio, and Tp‐e/QTc ratio in subclinical hypothyroidism (SH), but there have been no pediatric studies. Materials and methods A total of 40 SH patients were compared with 40 healthy children in respect to serum thyroid‐stimulating hormone (TSH), serum‐free level of triiodothyronine, and free level of thyroxine (fT4). SH diagnosis was accepted as TSH above the laboratory accepted upper limit (>4.2 mU/L) and normal fT4 values. The patient and control group data were compared by calculating the QT interval, QTc, QT dispersion (QTd), QTc dispersion (QTcd), Tp‐e, Tp‐e/QT ratio, and Tp‐e/QTc ratio on 12‐lead surface electrocardiogram. Results The mean age was 7.91 ± 3.6 years in the SH group and 8.8 ± 2.4 years in the control group. In the SH group, the minimum QT (QTmin) was determined to be statistically significantly lower (P < 0.001) and maximum QT (QTmax), QTd, QTcd, Tp‐e, Tp‐e/QT ratio, and Tp‐e/QTc ratio were statistically significantly higher (P = 0.028, P < 0.001, P = 0.003, P < 0.001, P = 0.001, P < 0.001, respectively). A positive correlation was determined between TSH and QTmax (r: +0.331, P = 0.037). Conclusions The current study is the first to have shown significantly increased QTd, QTcd, Tp‐e, Tp‐e/QT ratio, and Tp‐e/QTc ratio in children diagnosed with SH. A positive correlation was determined between TSH and maximum QT values, Tp‐e, Tp‐e/QT ratio, and Tp‐e/QTc ratio. These results suggest the need to further assess the long‐term risks of prolonged QT dispersion in the setting of subclinical hypothyroidism.