Is there a thyrotoxic cardiomyopathy in children?

Area of Science:

• Pediatric Endocrinology
• Cardiology
• Thyroid Disorders

Background:

• Thyrotoxicosis, a condition of excess thyroid hormones, can affect cardiovascular function.
• The impact of thyrotoxicosis on left ventricular function, particularly in pediatric populations, requires further investigation.

Purpose of the Study:

• To assess left ventricular ejection fraction (LVEF) at rest and during exercise in children with thyrotoxicosis.
• To determine the reversibility of cardiac dysfunction after achieving a euthyroid state.
• To explore the correlation between thyroid hormone levels and cardiac response.

Main Methods:

• Utilized radionuclide angiocardiography to measure LVEF in eight thyrotoxic children at rest and during graded exercise.
• Reassessed five patients after they returned to a euthyroid state.
• Correlated changes in LVEF with serum thyroxine and triiodothyronine concentrations.

Main Results:

• In thyrotoxic children, LVEF at rest was 69% ± 8%.
• Exercise response varied: four showed normal LVEF increase, while four had no significant change or a decrease.
• Abnormal LVEF response correlated inversely with serum thyroxine (r = -0.82) and triiodothyronine (r = -0.88) levels.
• After treatment, LVEF at rest was 64% ± 6% and increased normally during exercise in all reassessed patients.

Conclusions:

• Thyrotoxicosis can lead to diminished left ventricular reserve, presenting as a compensated functional cardiomyopathy in some children.
• This functional cardiomyopathy appears reversible with treatment of thyrotoxicosis.
• Thyroid hormone levels may influence the development of functional cardiomyopathy in pediatric thyrotoxicosis.