Abstract 20849: Age-Related Differences in Coronary Plaque Composition After Pediatric Heart Transplantation: A Virtual Histology Intravascular Ultrasound Study

Abstract

Background: Coronary vasculopathy (CAV) is the leading cause of late morbidity and mortality in both adult and pediatric heart transplant (HTx) recipients. Virtual histology intravascular ultrasound (VH-IVUS) may add important information in the evaluation of CAV progression. Indeed, the presence of VH-IVUS derived “inflammatory plaques” has been found to be associated with higher progression of CAV in adult patient recipients. The aim of this prospective study was to investigate tissue characterization of CAV by VH-IVUS in a pediatric cohort.

Methods: 40 patients (mean age: 17,1 ± 6,7 yrs, male= 23) underwent VH-IVUS analysis of the left anterior descending coronary artery 8.1± 4.6 years after HTx. Based on age, patients were divided in two groups (group A < 18 yrs; group B: ≥ 18 yrs; time from HTx: group A: 6.6 ± 2.9 yrs vs group B: 10.3±4.9 yrs, p=.01). According to VH-IVUS analysis, coronary allograft lesions were divided into “inflammatory” (VHD-IP) (necrotic core and dense calcium >30%) and “non-inflammatory” plaques (VHD-NIP) (necrotic core and dense calcium <30%).

Results: The mean percentage of fibrous, fibrofatty, dense calcified, and necrotic core plaques was 51±33%, 8±10%, 10±13%, and 4±7%, respectively. There were significant differences between group A and B in the mean percentage of fibrofatty and necrotic core plaques (5± 8 vs. 12± 11%,p= 0.05; 16±14 vs. 4±5%, p=0.002, respectively) while no significant differences have been found for fibrous and dense calcified plaques (45±41 vs. 58±21%, p=0.21, 3±6 vs. 6±8%, p= 0.08, respectively). The presence of VHD-IP at baseline was significantly more prevalent in the group B than group A (22 vs 8%, p=0.03). In both groups, type of plaque was not correlated with time from HTx (r=0.51).

Conclusions: VH-IVUS provides to identify distinct pattern of CAV in pediatric HTx, allowing early stratification of lesions. Younger patients with CAV exhibit a lower prevalence of inflammatory plaques, independently of time from HTx.