High free thyroxine levels are associated with QTc prolongation in males

Noord, Charlotte van; Deure, Wendy M van der; Sturkenboom, Miriam; Straus, Sabine M. J. M.; Hofman, Albert; Visser, Theo J.; Kors, Jan A.; Witteman, Jacqueline C. M.; Stricker, Bruno H. Ch.

doi:10.1677/joe-08-0140

Cited by 30 publications

(33 citation statements)

References 45 publications

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“…In addition, since thyroid hormones were available in only a minority of the study population, we could not assess the effect of thyroid dysfunction on our results. However, we do not expect that thyroid hormones would be a strong confounder, since we have shown previously that (sub) clinical hyperthyroidism was not associated with diabetes mellitus in the Rotterdam Study (41).…”

Section: Discussionmentioning

confidence: 90%

Serum glucose and insulin are associated with QTc and RR intervals in nondiabetic elderly

Noord

Sturkenboom²,

Straus³

et al. 2010

European Journal of Endocrinology

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Aims: To study whether nondiabetic persons with impaired fasting serum glucose and hyperinsulinemia have QTc/QT interval prolongation and RR interval shortening in the electrocardiogram (ECG), and whether these were associated with an increased risk of sudden cardiac death. Methods: This study consisted of two analyses. First, a cross-sectional analysis was used as part of the population-based Rotterdam Study including 1050 men and 1520 women (R55 years) without diabetes mellitus. Participants in round 3 of the Rotterdam Study for whom an ECG and fasting serum glucose and fasting insulin measurements were available were eligible for the study. Participants using digoxin or QTc-prolonging drugs and participants with left ventricular hypertrophy and left and right bundle branch block were excluded. The endpoints of the study were the lengths of the QTc, QT, and RR intervals. The associations were examined by means of linear regression analysis. Secondly, in all 6020 participants of the Rotterdam Study with an ECG, the associations between the QTc, QT, and RR intervals and sudden cardiac death were examined by means of Cox regression analysis. Results: Overall, there was a significant association between impaired fasting serum glucose and the QTc interval with an increase of 2.6 ms (95% confidence interval (CI): 0.3; 5.0) in those with fasting glucose O6 mmol/l. Hyperinsulinemia was also associated with QTc prolongation (3.0 ms (0.8; 5.3)) in those with fasting insulin R100 pmol/l. Impaired fasting glucose (IFG) and hyperinsulinemia were significantly associated with a decrease of the RR interval (K33.7 ms (K48.8; K18.6) and K44.4 ms (K58.7; K30.0) respectively). Participants in the fourth quartile of the QTc and QT intervals had a significantly increased risk of sudden cardiac death compared to participants in the first quartile (hazard ratio (HR) 2.87 (95% CI: 2.02-4.06); HR 3.05 (1.99-4.67) respectively). Furthermore, there was a significant inverse association between the fourth quartile of the RR interval compared to the first quartile and the risk of sudden cardiac death )).Conclusion: In this population-based study, we demonstrated that IFG and hyperinsulinemia are associated with a significantly increased QTc interval and with significant shortening of the RR interval, the latter probably due to an increased sympathetic activity. In addition, we demonstrated that both a prolonged QTc interval and a shortened RR interval are associated with an increased risk of sudden cardiac death.

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Section: Discussionmentioning

confidence: 90%

Serum glucose and insulin are associated with QTc and RR intervals in nondiabetic elderly

Noord

Sturkenboom²,

Straus³

et al. 2010

European Journal of Endocrinology

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“…28 This hyperdynamic state, which causes many of the symptoms in hyperthyroid patients, could be one of the mechanisms explaining the relation between thyroid hormone and SCD. Furthermore, thyroid hormones have been shown to lead to QT-interval prolongation, 29,30 which, in turn, is related to cardiovascular disease, in general, 31 and SCD, in particular. 18 Another pathway could be through various cardiovascular risk factors related to thyroid dysfunction, and thus leading to ischemic heart disease, in turn, a large contributor in SCD.…”

Section: Discussionmentioning

confidence: 99%

Thyroid Function and Sudden Cardiac Death

et al. 2016

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Original research article BACKGROUND:The association between thyroid function and cardiovascular disease is well established, but no study to date has assessed whether it is a risk factor for sudden cardiac death (SCD). Therefore, we studied the association of thyroid function with SCD in a prospective population-based cohort. METHODS:Participants from the Rotterdam Study ≥45 years with thyroidstimulating hormone or free thyroxine (FT4) measurements and clinical follow-up were eligible. We assessed the association of thyroid-stimulating hormone and FT4 with the risk of SCD by using an age-and sex-adjusted Cox proportional-hazards model, in all participants and also after restricting the analysis to euthyroid participants (defined by thyroid-stimulating hormone 0.4-4.0 mIU/L). Additional adjustment included cardiovascular risk factors, notably hypertension, serum cholesterol, and smoking. We stratified by age and sex and performed sensitivity analyses by excluding participants with abnormal FT4 values (reference range of 0.85-1.95 ng/ dL) and including only witnessed SCDs as outcome. Absolute risks were calculated in a competing risk model by taking death by other causes into account. RESULTS:We included 10 318 participants with 261 incident SCDs (median follow-up, 9.1 years). Higher levels of FT4 were associated with an increased SCD risk, even in the normal range of thyroid function (hazard ratio, 2.28 per 1 ng/dL FT4; 95% confidence interval, 1.31-3.97). Stratification by age or sex and sensitivity analyses did not change the risk estimates substantially. The absolute 10-year risk of SCD increased in euthyroid participants from 1% to 4% with increasing FT4 levels.CONCLUSiONS: Higher FT4 levels are associated with an increased risk of SCD, even in euthyroid participants.thyroid Function and sudden cardiac Death a Prospective Population-Based cohort study

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“…While ECG abnormalities in patients with hypo- and hyperthyroidism are well established, relatively little is known about how variations in thyroid hormone levels within the normal range affect the electrical activity of the heart in the general population [11]–[12]. This study aimed to evaluate the association of total thyroxine (T4) and thyrotropin (TSH) levels with ECG parameters (heart rate, PR interval, QRS duration, QT interval, and JT interval) in a representative sample of the general US population.…”

Section: Introductionmentioning

confidence: 99%

Thyroid Hormones and Electrocardiographic Parameters: Findings from the Third National Health and Nutrition Examination Survey

et al. 2013

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IntroductionAltered thyroid status exerts a major effect on the heart. Individuals with hypo- or hyperthyroidism showed various changes in electrocardiograms. However, little is known about how variations in thyroid hormone levels within the normal range affect electrical activities of the heart in the general population.Methods and ResultsWe conducted a cross-sectional analysis of 5,990 men and women from the Third National Health and Nutrition Examination Survey. Serum total T4 was measured by immunoassay and TSH was measured by chemiluminescent assay. We categorized T4 and TSH into 7 groups with cut-offs at the 5th, 20th, 40th, 60th, 80th, and 95th percentiles of the weighted population distribution. Electrocardiographic parameters were measured from the standard 12-lead electrocardiogram. We found a positive linear association between serum total T4 level and heart rate in men, and a U-shape association between T4 and PR interval in men and women. TSH level was positively associated with QRS interval in men, while a U-shape association between TSH and QRS was observed in women. No clear graded association between thyroid hormones and corrected QT or JT was found, except that men in the highest category of T4 levels appeared to have longer corrected QT and JT, and men in the lowest category of T4 appeared to have shorter corrected QT and JT.ConclusionsVariation in thyroid hormone levels in the general population, even within the normal range, was associated with various ECG changes.

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High free thyroxine levels are associated with QTc prolongation in males

Cited by 30 publications

References 45 publications

Serum glucose and insulin are associated with QTc and RR intervals in nondiabetic elderly

Serum glucose and insulin are associated with QTc and RR intervals in nondiabetic elderly

Thyroid Function and Sudden Cardiac Death

Thyroid Hormones and Electrocardiographic Parameters: Findings from the Third National Health and Nutrition Examination Survey

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