Detection of Age- and Time-dependent Differences of Cardiac Allograft Vasculopathy by OCT

Objectives: Cardiac allograft vasculopathy (CAV) limits survival after heart transplantation (HTx). Outcome depends on age at HTx and posttransplant time. Previous OCT studies have suggested an impact of intima to media ratio (I/M) on angiographic findings in adults. Studies comparing the development in pediatric and adult HTx patients are lacking. We evaluated CAV in pediatric versus adult patients using optical coherence tomography (OCT) at corresponding posttransplant intervals between OCT and HTx: < 10 and &≥ 10 years.

Methods: Retrospective OCT-analysis of 33 pediatric (cohort P) and 28 adult HTX patients (cohort A). HTX patients with donor age &≥18 years were excluded from cohort P. The patient population was divided into four groups: cohorts with an interval < 10 years were defined as P1 (n = 17; mean age at HTX, 3.9 ± 3.4 years) and A1 (n = 13; 45.8 ± 10.5 years), cohorts with an interval &≥ 10 years as P2 (n = 16; mean age at HTX, 2.5 ± 3.5 years) and A2 (n = 15; 47.5 ± 11.4 years). We used a novel quantification method, measuring coronary intima thickness (IT) and media thickness (MT) per quadrant every 5 mm. Intima to media ratio (I/M) was assessed, and I/M > 1 was considered as relative intimal hyperplasia (IH).

Result: P2 showed significantly higher absolute IT than P1 (p = 0.03), with absolute values of IT being significantly lower in P1 and P2 compared with corresponding A1 and A2. A relative IH was seen in both P1 and P2, and I/M was comparable at both time points. Mean I/M values of P1 and P2 were comparable to corresponding A1 and A2. In contrast, A1 and A2 presented with comparable absolute IT, but A2 showed significantly higher I/M values than A1 (p = 0.042; [Table 1]).

Table 1 OCT results

	Group P1	Group A1	p-Value	Group P2	Group A2	p-Value
Maximal IT (absolute IT), mm	0.2 (±0.15)	0.4 (±0.3)	0.02	0.3 (±0.1)	0.46 (±0.2)	0.019
Mean IT, mm	0.08 (±0.03)	0.2 (±0.15)	0.003	0.1 (±0.04)	0.2 (±0.08)	0.000
Maximal I/M, mm	5.4 (±3.8)	2.9 (±2.2)	0.042	5.7 (±2.4)	5.2 (±3.2)	0.623
Mean I/M, mm	2.0 (0.62)	1.4 (±1.01)	0.098	1.9 (±0.3)	2.3 (±1.1)	0.146

Conclusion: Relative intimal hyperplasia affects the pediatric coronaries already in the first 10 years after HTX and after 10 years CAV development differs depending on age at HTX.