title: Evaluation of Tp-e interval, Tp-e/QT ratio and Tp-e/QTc ratio in patients with subclinical hypothyroidism.
abstract: BACKGROUND
  Prolongation of the peak-to-end interval of the T wave (Tp-e) has been reported as associated with ventricular arrhythmias. The aim of this study was to investigate the ventricular repolarization by using the Tp-e interval, Tp-e/QT ratio and Tp-e/ QTc ratio in patients with subclinical hypothyroidism (SH).
  
  
  METHODS
  We studied 56 volunteers: These were 28 patients with SH (mean age 45 ± 11 years) and 28 healthy subjects (mean age 34 ± 8 years). All basic biochemical parameters were analyzed and electrocardiograms (ECGs) were recorded. RR and QT intervals, QTc, Tp-e intervals and the Tp-e/QT and Tp-e/QTc ratios were calculated. The categorical and numerical variables were compared using the chi-square test and independentttest, respectively. Correlations were analyzed using the Spearman and Pearson correlation tests.
  
  
  RESULTS
  We found no difference between QT and QTc intervals between groups. In the subjects with SH, the Tp-e intervals (87 ± 5 ms, 66 ± 5 ms,p<0.01), Tp-e/ QT ratio (0.23 ± 0.03, 0.18 ± 0.01,p<0.01) and Tp-e/QTc ratio (0.21 ± 0.02, 0.16 ± 0.01,p<0.01) were increased compared with healthy subjects. We also found positive correlations between levels of thyroid stimulating hormone (TSH) and Tp-e (r= 0.72,p<0.01), Tp-e/ QT ratio (r= 0.67p<0.01), Tp-e/ QTc ratio (r= 0.68,p<0.01). In the subjects with SH, Left Ventricular Myocardial Performance Index (LV-MPI) was increased compared with the healthy subjects (0.64 ± 0.08, 0.59 ± 0.09,p= 0.066) although it was not significant.
  
  
  CONCLUSIONS
  Compared with healthy subjects, patients with SH demonstrated longer Tp-e intervals, and higher Tp-e/QT and Tp-e/QTc ratios. TSH levels were positively correlated with Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio.
authors.affiliation: Department of Cardiology, Sisli Hamidiye Etfal Education and Research Hospital, 34360 Sisli/Istanbul, Turkey.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Gürdal
authors.affiliation: Department of Internal Medicine, Sisli Hamidiye Etfal Education and Research Hospital, Istanbul, Turkey.
authors.forename: Hatice
authors.initials: H
authors.lastname: Eroğlu
authors.affiliation: Department of Cardiology, Sisli Hamidiye Etfal Education and Research Hospital, Istanbul, Turkey.
authors.forename: Füsun
authors.initials: F
authors.lastname: Helvaci
authors.affiliation: Department of Cardiology, Sisli Hamidiye Etfal Education and Research Hospital, Istanbul, Turkey.
authors.forename: Mutlu Çağan
authors.initials: MÇ
authors.lastname: Sümerkan
authors.affiliation: Department of Biostatistic, Atatürk University Faculty of Medicine, Erzurum, Turkey.
authors.forename: Kamber
authors.initials: K
authors.lastname: Kasali
authors.affiliation: Department of Cardiology, Sisli Hamidiye Etfal Education and Research Hospital, Istanbul, Turkey.
authors.forename: Şükrü
authors.initials: Ş
authors.lastname: Çetin
authors.affiliation: Department of Cardiology, Sisli Hamidiye Etfal Education and Research Hospital, Istanbul, Turkey.
authors.forename: Gökhan
authors.initials: G
authors.lastname: Aksan
authors.affiliation: Department of Cardiology, Sisli Hamidiye Etfal Education and Research Hospital, Istanbul, Turkey.
authors.forename: Kadriye
authors.initials: K
authors.lastname: Kiliçkesmez
keywords: Tp-e interval; Tp-e/QTc ratio; subclinical hypothyroidism; ventricular arrhythmias