Optical coherence tomography for characterization of cardiac allograft vasculopathy in late survivors of pediatric heart transplantation

Background Optical coherence tomography (OCT) has been shown to reliably detect cardiac allograft vasculopathy (CAV). In recent studies performed in adult heart transplant (HTx) recipients, OCT revealed the presence of vulnerable plaques and complicated coronary artery lesions, thus challenging the current concept that CAV disease is a diffuse concentric and fibrosing vasculopathy. The aim of our study was to characterize CAV by OCT in a young population of HTx recipients. Methods We prospectively enrolled 21 young HTx recipients (mean age 27 years, range 22 to 38 years) to undergo OCT of the left anterior descending coronary artery (LAD) in addition to annual CAV screening by coronary angiography and virtual histology intravascular ultrasound (VH-IVUS). Quantitative OCT analysis was performed at the site of maximal intimal thickness (MIT) for each LAD segment. Results Patients were 27 years old with a mean time from cardiac transplantation of 14.7 ± 6.8 years. All patients exhibited intimal hyperplasia with an abnormal (>1) intima-to-media ratio. The median (interquartile range) MIT values by OCT were 0.37 (0.22 to 0.54) mm, 0.46 (0.29 to 0.54) mm and 0.34 (0.25 to 0.49) mm in the distal, middle and proximal LAD segments, respectively. Qualitative OCT analysis rarely showed features of vulnerable plaque or complicated lesions. Consistently, at VH-IVUS, the prevalent component at the site of MIT per vessel assessed by OCT was fibrous tissue. Conclusions Unlike recent evidence in adult HTx recipients, OCT findings of vulnerable plaque and complicated coronary lesions were found to be rare among late survivors of pediatric HTx.