Intravascular Ultrasound in the Diagnosis of Cardiac Allograft Vasculopathy in Pediatric Heart Transplant Recipients: A 20 Year Single Center Review

Abstract

Purpose: The purpose of this study was to retrospectively evaluate the longterm use of intravascular ultrasound (IVUS) in diagnosing cardiac allograft vasculopathy (CAV) in pediatric heart transplant recipients. Methods: IVUS was part of the annual evaluation starting at age 7, and was repeated at least every other year whilst in our care. Morphometric analysis was performed on each study at 10 randomized segments and was graded using Stanford classification (SC). A SC grade of 3 (moderate) or 4 (severe) was considered significant for CAV. The presence of SC 3 or 4 (IVUS +) was compared to graft loss, retransplant, and cause of death: CAV, acute rejection, lymphoproliferative disease, other. IVUS + was compared to age at transplant (< 1 year, < 1 month), pre-transplant diagnosis, donor age, prolonged ischemic time, CMV, prior bypass, early and late acute rejection, and > 5 rejection episodes. Chi square analysis and Kaplan-Meier were used to compare data. A P-value of 0.05 was considered significant. Results: Since 1997, 213 patients underwent 804 IVUS studies. There were no major complications. Three patients had transient vasospasm. IVUS + correlated with graft loss, re-transplant, and CAV as a cause of death (p < 0.001). There was no significant correlation with other causes of death. There was a significant difference in long-term freedom from graft loss (P < 0.001) and CAV (P < 0.001) (figures). Heart transplant at < 1 year and those with HLHS were less likely to be IVUS + (both P = 0.003). Older donor age and prior bypass were more likely to be IVUS + (both P = 0.05). Other parameters were not significant. Conclusion: The presence of moderate to severe intimal thickening (Stanford Class 3 or 4) on IVUS was strongly associated with the development of CAV and eventual graft loss over time. Future research should focus on early intervention and long-term follow up in this high-risk population (Figure presented).