Utility of Early Intravascular Ultrasound after Pediatric Heart Transplantation

Abstract

Intravascular ultrasound (IVUS) has been used in adult heart transplant (HTX) recipients early after transplant to assess risk for long-term outcomes, along with differences in therapeutic targets for the treatment of cardiac allograft vasculopathy (CAV). Little is known about the utility of IVUS early after pediatric HTX. We evaluated the use of IVUS early (<5 years) after pediatric HTX. All pediatric HTX recipients at our hospital who underwent coronary evaluation via IVUS within 5 years after transplant were included. Maximal intimal thickness (MIT) and associated Stanford IVUS class (SIC) were analyzed and subjects were stratified into two groups [SIC 1-2 (trivial/mild) vs. 3-4(moderate/severe)]. Chi-square, t-test, and Kaplan Meier analyses were undertaken to evaluate association of SIC with long-term outcomes [CAV (diagnosed by angiography or pathology), graft loss from all causes, graft loss from CAV, and death]. Seventy-one subjects had IVUS performed within 5 years after HTX. Fifty-four (76%) were SIC 1-2, while 17 (24%) were SIC 3-4. Median time from transplant at IVUS was 3.8 & 3.5 years, respectively (p=0.59). Median age at transplant was 6.4 & 8.7 years, respectively (p=0.80). MIT was 0.17±0.06 & 0.53±0.23 mm, respectively (p<0.001). Freedom from CAV and graft loss from CAV were lower in the SIC 3-4 group [CAV HR 2.7 (1.4-5.4), p=0.01 and graft loss from CAV HR 3.4 (1.3-8.9), p=0.005, respectively] (Figures). Graft loss from all causes and patient survival were not different between the groups (p=NS). Early changes in IVUS (<5 years post-HTX) were associated with the development of CAV and graft loss from CAV over time. These findings show the utility of performing IVUS early after pediatric HTX.