The relation of thyroid function and ventricular repolarization: decreased serum thyrotropin levels are associated with short rate-adjusted QT intervals.
BACKGROUND
The linkage of thyroid dysfunction with ventricular repolarization properties has not been investigated extensively, although alterations might be associated with an increased ventricular vulnerability.


OBJECTIVE
The objective of the study was to investigate whether there is an association between functional thyroid status and rate-adjusted QT intervals (QTc).


METHODS
The population-based Study of Health in Pomerania included 4310 subjects aged 20-79 yr. Data of 3610 subjects (1862 women and 1748 men) without branch bundle blocks or pacemaker were available for the present analyzes.


METHODS
QTc with respect to thyroid status. Short QTc was defined below the 25th percentile, and long QTc above the 75th percentile of the gender-specific distribution.


RESULTS
TSH levels were positively associated with QTc independent from potential confounders in multivariable analyses (P for trend = 0.001). Subjects with decreased TSH levels had shorter QTc than those with normal TSH levels (426.4 +/- 8.2 vs. 430.2 +/- 8.2; P < 0.001). Adjusted odds ratios for short QTc in subjects with elevated, normal, and decreased TSH were 0.87 (95% confidence interval 0.58-1.31), 1.00 (reference), and 1.53 (95% confidence interval 1.16-2.03), respectively (P for trend = 0.008).


CONCLUSIONS
TSH levels were positively related to QTc in a population-based sample. Subjects with decreased serum TSH levels had an increased risk for short QTc. Whether these findings are of clinical significance has to be investigated by further studies.
Dörr
Marcus
M
Department of Internal Medicine B, M. Ernst Moritz Arndt University, Friedrich Loeffler Strasse 23 a, D-17475 Greifswald, Germany. mdoerr@uni-greifswald.de
Ruppert
Jörg
J
Robinson
Daniel M
DM
Kors
Jan A
JA
Felix
Stephan B
SB
Völzke
Henry
H
D000328:Adult; D000368:Aged; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006306:Health Surveys; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013960:Thyroid Function Tests / Q000379:methods; D013961:Thyroid Gland / Q000502:physiology*; D013972:Thyrotropin / Q000097:blood*; D016276:Ventricular Function
D013972:Thyrotropin