Association between the vasa vasorum and the atherosclerotic changes in cardiac allograft vasculopathy: volumetric analysis

Aims The current study was designed to test that vasa vasorum (VV) plays a role in the progression of cardiac allograft vasculopathy (CAV) in patients with heart transplantation (HTX). Methods and results Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) were performed in the left anterior descending artery in 19 segments of 19 HTX patients (median 2.1 years from HTX). Each segment is composed of both the continuous lesions: (i) CAV area: intimal thickness > 0.5 mm with 5 mm length and (ii) VV area: intimal thickness <= 0.5 mm with 5 mm length. The per cent VV volume (VV volume/vessel volume x 100, % VV) was evaluated in the VV area with OCT (in CAV area VV cannot be assessed because of limited penetration power of OCT). A year later, the association between the baseline %VV and the change in per cent plaque volume (plaque volume/vessel volume x 100, %PV) was evaluated with IVUS. To a normal distribution, Delta%PV (follow-up % PV-initial % PV) was undergone square root transformation. The correlations between the %VV at baseline study and square root-Delta%PV were significant both in the CAV area and in the VV area (r = 0.787, P < 0.001 and r = 0.701, P < 0.001, respectively). In multivariable analysis, only the %VV was significantly correlated with square root-Delta%PV in both areas. Conclusion The current study demonstrated a significant association between the VV volume and the progression of plaque volume in both the CAV area and the VV area. Thus, VV may be a potential predictor and possible therapeutic target to attenuate CAV.