Repeated episodes of thrombosis as a potential mechanism of plaque progression in cardiac allograft vasculopathy

Abstract

The pathogenesis of cardiac allograft vasculopathy (CAV) remains complex and may involve multiple mechanisms. We tested the hypothesis that the multilayer (ML) appearance, an intravascular ultrasound (IVUS) finding suggestive of repetitive thrombosis, is associated with plaque progression in heart transplant (HTx) recipients. Our study population consisted of 132 HTx recipients undergoing at least two grayscale and virtual histology (VH)-IVUS examinations. A retrospective serial analysis was performed between the first (baseline) and the last (follow-up) IVUS data during a median follow-up of 3.0 years. The subjects were divided into two groups based on the presence of the ML appearance on the baseline IVUS. At baseline, subjects with ML appearance (n = 38) had a longer time elapsed since transplant, larger vessel volume, and larger plaque volume than those without (n = 94) (all P < 0.01). Intraluminal thrombi and plaque ruptures were identified only in subjects with ML appearance (P < 0.01 vs. those without). More subjects with ML appearance at baseline developed subsequent ML formation compared with those without [21 (55%) vs. 22 (23%), P < 0.01] during follow-up. There was an increase in plaque volume, necrotic core volume, and dense calcium volume in subjects with ML appearance (all P < 0.01 vs. those without). Multivariable linear regression analysis showed that ML appearance was a potential predictor of plaque progression (regression coefficient 0.28, 95% CI 0.10-0.45, P < 0.01). The current study demonstrates that a finding of ML appearance, indicative of repeated episodes of mural thrombosis, is not infrequent in asymptomatic HTx recipients and possibly contributes to progression of CAV.