Frequency of hypothyroidism after cardiac catheter in infants with congenital heart diseases: A single center prospective study

This study aims to determine the incidence, potential onset and clinical course of hypothyroidism following cardiac catheter (CC) in infants with congenital heart diseases (CHD) and to evaluate the predictors for hypothyroidism in this vulnerable group. This prospective study included 102 patients with CHD, aged ≤ 3 years who underwent CC. Thyroid function tests were assessed before CC, one day, one week, two weeks and four weeks after the procedure. 12% of the studied group showed hypothyroidism four weeks after CC. Univariate analysis revealed that the significant predictors of hypothyroidism following CC are aortic stenosis (RR=10.0 (1.49-66.99), P=0.018), duration of fluoroscopy (RR=1.12 (0.99-1.26), P=0.05), and total cumulative dose of iodinated contrast media (iCM) (RR=1.01 (1.003 -1.01), P=0.019). Multivariate analysis revealed that iCM cumulative dose was the only significant predictor of developing hypothyroidism (RR=1.00 (1.00-1.01), 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 (26.1 ml/kg), (sensitivity: 83.3%, specificity: 65.1%), while the cut-off point of fluoroscopy duration which predicts development of hypothyroidism is 24 minutes, (sensitivity: 83.3%, specificity: 65.9%). In a median follow-up duration of 20 months, acquired hypothyroidism after CC persists in 5% of this cohort. Conclusion: Exposure to higher dose of iCM and longer duration of fluoroscopy during CC are risk factors for evolution of hypothyroidism. We recommend assessment of thyroid profile 4 weeks after CC particularly in patients who received a dose of iCM higher than 8.7 gm/kg and/or exposed to fluoroscopy for more than 24 minutes.