BackgroundThe diffuse nature of cardiac allograft vasculopathy makes early detection of the disease by traditional noninvasive methods or coronary angiography difficult. The aim of this study was to determine if there is a relation between abnormalities in vessel wall morphology, as assessed by intracoronary ultrasound, and a decreased vasodilatory response to the endothelium-dependent vasodilator papaverine hydrochloride and if cardiac allograft vasculopathy detected by coronary angiography is associated with specific intracoronary ultrasound findings.Methods and ResultsTwenty-three heart transplant recipients underwent 25 intracoronary ultrasound studies and 24 studies of coronary vasomotor tone 10 days to 8.3 years after surgery using a 20-mHz intracoronary ultrasound catheter. The studies were divided in two groups according to the presence (n=7, group 1) or absence (n= 18, group 2) of angiographically evident cardiac allograft vasculopathy. Qualitative assessment of vessel wall morphology and quantitative analysis of the vasodilator response to the injection of papaverine hydrochloride into the coronary artery distal to the imaging site were performed off-line, and results for the two study groups were compared. A significantly higher percentage of patients with than without angiographic evidence of cardiac allograft vasculopathy had a three-interface vessel wall morphology by intracoronary ultrasound (100% versus 11%,P< .001). In two recipients who underwent two serial studies, the appearance of three interfaces in the vessel wall or a progressive thickening of the inner interface of the vessel wall occurred in conjunction with the appearance of angiographic cardiac allograft vasculopathy. The vasodilator response to papaverine was less in patients with than in those without angiographically evident cardiac allograft vasculopathy both in terms of absolute and relative increases in lumen diameter (+0.1±0.12 mm versus +0.3±0.17 mm,P< .05, and +5.1±5.3% versus +8.2±5.3%,P= NS) and lumen crosssectional area (+0.5±0.6 mm2versus +1.7±1.1 mm2,P< .02, and +7.1±8.8% versus 16.6±11.0%,P= .055), respectively.ConclusionsIntracoronary ultrasound assessment of vessel wall morphology and evaluation of vascular response to endothelium- dependent vasodilators are useful techniques for detecting cardiac allograft vasculopathy.