Key result
L-thyroxine is linked to a ~33% reduction in QT dispersion in primary hypothyroidism.
Why the study?
The effect of L-thyroxine treatment on ECG parameters, such as QT dispersion, in patients with primary hypothyroidism was investigated due to cardiovascular manifestations of hypothyroidism.
Does L-thyroxine treatment reduce QT dispersion in patients with primary hypothyroidism?
Observational (n=18)
Single-blind
No
Does L-thyroxine treatment reduce QT dispersion in patients with primary hypothyroidism?
Absolute Event Rate: 30% vs 45%
p-value: p=0.008
L-thyroxine replacement therapy significantly reduces QT dispersion in patients with primary hypothyroidism, which may lower the risk of malignant ventricular arrhythmias.
L-thyroxine was associated with reduced QT dispersion in hypothyroidism; hypothesis-generating and requires prospective confirmation before practice change.
Hypothyroidism has various cardiovascular manifestation and exhibits electrocardiographic change. The QT dispersion on surface ECG reflects regional variations in myocardial repolarization. The effect of L-thyroxine treatment on ECG parameters, such as QT dispersion, in patients with primary hypothyroidism were investigated. This study involved 18 patients (3 men, 15 women, ages: 48+/-18 yr) with primary hypothyroidism. All patients were checked with a standard 12-lead ECG before and after L-thyroxine treatment. Various ECG parameters were then measured twice. The mean L-thyroxine treatment duration was 22+/-2.7 months. The mean thyroid-stimulating hormone levels of patients before and after therapy were 40.2+/-29.8 microU/mL, 3.6+/-4.6 microU/mL (p<0.001) and free-T4 levels were 0.44+/-0.38 ng/dL, 1.51+/-0.39 ng/dL (p<0.001). After L-thyroxine treatment, QT interval (395+/-42 vs. 380+/-24 msec, p<0.05), QTc interval (434+/-32 vs. 417+/-23 msec, p<0.05), QT dispersion (45+/-23 vs. 30+/-13 msec, p=0.008), QTc dispersion (49+/-23 vs. 32+/-14 msec, p=0.005) significantly decreased. There were no significant changes in the PR and RR intervals, as well as the QRS duration. Our findings suggest that the thyroid hormone affects ventricular inhomogenicity, and that L-thyroxine replacement therapy may reduce malignant ventricular arrhythmia and sudden cardiac death in primary hypothyroidism.
No takes yet. Share an insight, caveat, or question.
Kweon et al. (2007) conducted an observational in Primary hypothyroidism (n=18). L-thyroxine vs. Baseline (before treatment) was evaluated on QT dispersion (p=0.008). L-thyroxine treatment significantly decreased QT dispersion from 45 msec to 30 msec (p=0.008) and QTc dispersion from 49 msec to 32 msec (p=0.005) in patients with primary hypothyroidism.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: