Optical Coherence Tomography (OCT) Detects Early Coronary Changes Related to Cardiac Allograft Vasculopathy in Pediatric Transplant Recipients: Results from a Multicenter Study Group

Background: Cardiac allograft vasculopathy (CAV) is a common cause of graft failure and mortality in pediatric heart transplant (HTx) recipients. CAV is diagnosed by coronary angiography which is unable to detect early changes that do not cause luminal narrowing.

Hypothesis: (1) Optical coherence tomography (OCT) can detect angiographically-silent coronary changes; (2) OCT might detect early CAV and may be used for therapeutic interventions and follow-up CAV.

Methods: The International Pediatric multicenter OCT registry includes 75 HTx recipients (age at Tx 4.6 ± 4.3 years) from three centers in Canada and Europe. Patients underwent ≥1 assessment of ≥1 coronary artery using OCT-system (Dragonfly, St Jude Medical) during routine cardiac catheterization and data from ≥10 cross-sectional images ≥1 mm apart; we identified the maximal intimal thickness at each vessel. CAV was classified by angiography according to the ISHLT criteria with investigators blinded to OCT findings. We used multi-level regression to assess between-group differences. CAV was defined as Intima-media thickness >0.2 mm.

Results: We included 93 OCT-runs from 75 patients (mean age 11.8 ± 4.0 years at OCT; 54% male). In newly diagnosed CAV (all grade 1), maximal intimal thickness was significantly greater (median 0.31 mm; IQR 0.22–0.56) compared with those without CAV (0.18 mm; 0.12–0.23; p < 0.001). In 12/75 patients, a change in medical treatment was made after first OCT and 10/12 patients were angiographically silent. Intimal thickness was greater in cases where medical management was changed compared with those where it was not changed (0.29 mm; 0.18–0.38 vs. 0.18 mm; 0.12–0.22; p < 0.001). Serial assessments were done in 17/75 patients (time between OCT assessments 1.6 ± 0.6 years). Intimal thickness did not change significantly over time in those with or without CAV. One patient was diagnosed with CAV at the second OCT and had angiographically-silent severe intimal thickening at first OCT (0.43 mm).

Conclusion: OCT can detect changes in intimal thicknesses that are angiographically silent. Children with a new diagnosis of CAV have more pronounced intimal thickening than those without CAV. These findings suggest that OCT findings may be useful in evaluating for CAV after heart transplantation.

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