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The effect of cardiac catheterization on thyroid functions in infants with congenital heart diseases: a prospective
Boshra A Elbaz1, Hala M Elmarsafawy2,3, Wafaa N Laimon4
1Department of Pediatrics, Neonatology Unit, Mansoura New General Hospital, Mansoura, Egypt.
Insights
Iodinated contrast media (iCM) and fluoroscopy duration during cardiac catheterization are significant risk factors for developing hypothyroidism in infants with congenital heart disease. Monitoring thyroid function post-procedure is crucial, especially for high-risk patients.
Area of Science:
- Pediatric Cardiology
- Endocrinology
- Radiology
Background:
- Excess iodine intake can transiently inhibit thyroid hormone synthesis (Wolff-Chaikoff effect).
- Infants with congenital heart disease (CHD) have a higher predisposition to hypothyroidism due to thyroid morphology and contrast media exposure.
Purpose of the Study:
- To determine the incidence, clinical course, and risk factors of hypothyroidism following cardiac catheterization (CC) in infants with CHD.
- To identify specific thresholds for iodinated contrast media (iCM) and fluoroscopy duration associated with hypothyroidism.
Main Methods:
- Prospective study of 115 infants with CHD (≤3 years) undergoing CC, compared to 100 healthy controls.
- Thyroid function tests (TFTs) were performed before CC, 4 weeks after, and 2 weeks later if abnormal.
- Risk factors including iCM dose and fluoroscopy duration were analyzed.
Main Results:
- Hypothyroidism was detected in 12% of infants 4 weeks post-CC.
- Higher iCM dose (RR=2.5) and longer fluoroscopy duration (RR=2.12) were significant univariate predictors.
- Multivariate analysis identified iCM dose as the sole significant predictor (RR=2.10); cut-off points were 8.7 gm/kg for iCM and 24 min for fluoroscopy.
Conclusions:
- Increased iCM dose and prolonged fluoroscopy during CC are risk factors for hypothyroidism in infants with CHD.
- Recommend thyroid profile assessment 4 weeks post-CC for infants receiving >8.7 gm/kg iCM or >24 min fluoroscopy.
Abstract:
This study aims to determine the incidence, clinical course, and risk factors of hypothyroidism following cardiac catheter (CC) in infants with congenital heart diseases (CHD). This prospective study involved 115 patients with CHD, all aged 3 years or younger, who underwent CC, as well as 100 healthy age- and sex-matched controls. Baseline thyroid function tests (TFTs) were conducted for both the patients and controls. In the CHD cohort, TFTs were reassessed 4 weeks after the CC, and for those with abnormal TFT values at this time, the tests were repeated after 2 weeks. Levothyroxine was started for patients with persistent abnormal TFTs, at 4 weeks and 6 weeks assessments after CC. Four weeks after CC, 12% of the studied group exhibited hypothyroidism. Univariate analysis identified significant predictors of hypothyroidism following CC: aortic stenosis (RR = 10.0 (1.49-66.99), P = 0.018), duration of fluoroscopy during CC (RR = 2.12 (0.99-4.26), P = 0.05), and total iodinated contrast media (iCM) during CC (RR = 2.5 (1.35-3.55), P = 0.019). Multivariate analysis indicated that iCM dose was the sole significant predictor of developing hypothyroidism (RR = 2.10 (1.01-3.23), P = 0.04). ROC curve analysis showed that the cut-off point of iCM dose for prediction of hypothyroidism evolution is 8.7 gm/kg, (sensitivity: 83%, specificity: 65%), while the cut-off point of fluoroscopy duration which predicts the development of hypothyroidism is 24 min (sensitivity: 83%, specificity: 66%). Acquired hypothyroidism after CC persisted in 4% of this cohort for 6 months.
Conclusion:
Higher doses of iCM and longer duration of fluoroscope during CC are risk factors for the evolution of hypothyroidism post-CC. We recommend assessing thyroid profile 4 weeks after CC, particularly in patients who received an iCM dose greater than 8.7 gm/kg and/or exposed to fluoroscopy for more than 24 min.
What Is Known:
• The use of excess iodine leads to transient inhibition of thyroid hormones biosynthesis via the Wolff-Chaikoff effect. • Infants with congenital heart diseases (CHD) are more prone to hypothyroidism due to higher frequency of abnormal thyroid morphology and routine exposure to supraphysiological doses of iodine.
What Is New:
• Exposure to a total dose of iodinated contrast media more than 8.7 gm/kg and a fluoroscopy duration more than 24 min during cardiac catheter are risk factors for the evolution of thyroid hypofunction following cardiac catheter.
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