BackgroundTransplant coronary artery disease (TxCAD) contributes to a large percentage of late morbidity and mortality among adult heart transplant recipients. Intracoronary ultrasound (ICUS) is a sensitive tool in the diagnosis of TxCAD in adult patients and has allowed analysis of factors contributing to disease development. Experience with ICUS in pediatrics, however, has been limited. By using ICUS we sought to determine the overall prevalence of TxCAD in pediatrics and to characterize factors associated with its development in this population. Methods: Eighty-six studies were performed in 51 pediatric patients a median of 3.4 years after heart transplantation. Evaluation included angiography and ICUS in 83 and angiography alone in 3 studies. Donor and recipient characteristics were obtained. The ICUS images were analyzed for intimal thickening and compared with coronary angiograms. The presence of any intimal thickening on ICUS was considered TxCAD. An intimal index and point of maximal intimal thickening (MIT) were measured. Vessel disease was graded 0 to 4 based on these Results: Results: Four patients had evidence of vasculopathy by angiography, whereas 32 patients (63%) had evidence of intimal proliferation by ICUS. Grade 2 or greater disease was present in 19 (37%) patients. A positive correlation was found when comparing time from transplant with intimal index and MIT (p < 0.001). No other factors were found to predict the development of disease. The overall prevalence of disease was 74% in patients studied at least 5 years after transplant. Conclusions: Intracoronary ultrasound can be performed safely in pediatric patients. Transplant coronary artery disease is common in infants and children after heart transplantation, although its prevalence appears to be less than in adult recipients at similar time intervals. We found no factor other than time from transplant was associated with development of disease.