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Published on: April 5, 2011
The relation of thyroid function and ventricular repolarization: decreased serum thyrotropin levels are associated
Marcus Dörr1, Jörg Ruppert, Daniel M Robinson
1Department of Internal Medicine B, M. Ernst Moritz Arndt University, Friedrich Loeffler Strasse 23 a, D-17475 Greifswald, Germany. mdoerr@uni-greifswald.de
Context:
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).
Design, Setting, And Participants:
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.
Main Outcome Measures:
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).
Conclusion:
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.
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