Background: Coronary allograft vasculopathy is the leading cause of late death after heart transplantation in children. It is poorly detected by conventional angiography. Intravascular ultrasound is invasive and costly. This study shows that magnetic resonance imaging (MRI) late gadolinium enhancement (LGE) of the coronary vessel wall can detect and grade coronary allograft vasculopathy.
Methods and results: Twenty-four children (10 male; age range, 9-17 years) underwent coronary angiography, intravascular ultrasound, and MRI. Maximal intimal thickness and mean intimal index were recorded. MRI included coronary magnetic resonance angiogram and LGE vessel wall imaging with 1.5 T (n=12) and 3.0 T (n=12). Ten healthy control subjects also underwent LGE MRI. Mean time posttransplantation was 5.5 years (range, 0.25-14 years). Seven patients had Stanford grade IV coronary allograft vasculopathy on intravascular ultrasound, 3 of whom had angiographic disease. Maximal intimal thickness and mean intimal index were 0.73±0.50 mm and 20.9±10.6%, respectively. On MRI, mean diameter of enhancement of vessel wall was 6.57±4.91 mm, and mean enhancement index (indexed to vessel lumen size) was 1.10±1.72. The control group showed little or no LGE. Correlation of LGE with maximal intimal thickness using the Pearson coefficient was 0.80 (P<0.001) and with mean intimal index was 0.92 (P<0.001). An MRI diameter >7.5 mm gave 86% sensitivity and 93% specificity.
Conclusions: LGE scores correlate well with traditional intravascular ultrasound measures. These promising early results encourage larger-scale clinical studies to investigate whether LGE MRI will allow closer follow-up and better prevention of coronary allograft vasculopathy in children.