UNLABELLED
The diffuse nature of allograft coronary artery disease (CAD) suggests that global myocardial blood flow (MBF) may decrease with time after transplantation; therefore the diagnosis of this disease remains problematic.
METHODS
To investigate whether PET detects a fall in allograft MBF over time, PET scans (108) were obtained from 43 heart transplant recipients. Thirty-five patients underwent two serial PET scans 1 yr apart. MBF was measured by PET using 13N-ammonia as a tracer. Coronary angiography was performed parallel with PET imaging and compared with perfusion rates measured by PET scans.
RESULTS
MBF measured by PET decreased sequentially with time. The mean MBF was 73 +/- 21, 56 +/- 13, 51 +/- 11 and 51 +/- 27 ml/min/100 g of tissue in patients surviving 3 mo, 1, 2 and 3 yr after transplantation, respectively. Significant MBF decrease occurred within 1 yr after transplantation. Sequential PET studies showed a decrease in MBF in 22 of 35 patients (63%). Mean MBF for the first and second scans was 65 +/- 18 and 54 +/- 16, respectively. MBF decrease was more profound in patients (n = 11) angiographic evidence of CAD. There was a trend towards increased rejection and CMV infection rates in patients with decreased MBF.
CONCLUSION
With time, PET detects a decrease in MBF in cardiac allografts. The frequency of MBF decrease detected by PET is concordant with the true incidence of allograft CAD, suggesting that sequential PET is a more sensitive modality for monitoring allograft CAD than angiography.