Comparative Study of Pediatric Coronary Allograft Vasculopathy Between Single Centers in North America and United Kingdom.

Background. Coronary allograft vasculopathy (CAV) is the leading cause of death after pediatric heart transplantation from 1 year postoperation. Anecdotal evidence suggests a difference in the severity of disease between UK and North America. We performed a comparative study using intravascular ultrasound (IVUS). Methods. Consecutive IVUS procedures from a single year were included from each center. Using standardized techniques, measurement of the vessel area, lumen area, and maximal intimamedial thickening (IMT) were performed with calculation of intimal index (II) for each slice. Mean II, mean IMT, and absolute maximum IMT were calculated along the left coronary artery for each patient. Transplant demographics and treatment details were included in the analysis. Results. One hundred four patients were included between the 2 centers. Interobserver variability for IVUS analysis was excellent. Patients were aged mean 14.2 (SD 3.3) years at the time of the study and 9.2 (SD 6.0) years earlier post-transplant procedure. UK patients were older, at transplant for a shorter time, and demonstrated more severe CAV. Multiple regression analysis demonstrated the detrimental effect of donor age and time from transplant on CAV severity and benefits of sirolimus use. Conclusions. The data show more severe CAV in the UK cohort despite significantly shorter time post-transplant. Donor age and time post-transplant were associated with more severe CAV and sirolimus use was associated with a reduction in IMT. This study demonstrates a marked difference in the prevalence of CAV in children between UK and North America. The causes are likely to be multifactorial; however, younger donors and recipients have significantly less disease.