A reliable, sensitive, non-invasive alternative for transvenous endomyocardial biopsy in detecting cardiac allograft rejection is desirable for optimal management of heart transplant patients. To establish whether (31)P magnetic resonance spectroscopy can become a non-invasive tool for detecting cardiac allograft rejection, the cardiac high-energy phosphate metabolism of human heart transplants was serially examined in 13 patients by means of (31)P MRS from post-operative day 13 to day 294, and compared with histologic evaluation of endomyocardial biopsies. Biopsy scores of 2 or higher, according to the Working Formulation criteria of Billingham et al., were considered to indicate rejection. Logistic regression, which was corrected for differences between the individual patients and the time after transplantation, showed no significant correlation between the occurrence of histologically detected rejection and the PCr:ATP ratio. However, using an analysis of variance, the PCr:ATP ratios of non-rejecting cases obtained within 50 days after transplantation (mean: 27 +/- 11 days) appeared to be significantly different from those obtained after post-operative day 50 [0.95 +/- 0.17 (n = 25) vs 1.17 +/- 0.17 (n = 32), mean +/- SD; p < 0.01]. No significant difference was observed between the PCr:ATP ratios obtained 100 days after transplantation (mean: 162 +/- 52 days) and the PCr:ATP ratios in the hearts of healthy volunteers [1.18 +/- 0. 18 (n = 19) and 1.23 +/- 0.17 (n = 6), mean +/- SD, respectively; p = 0.55]. The PCr:ATP ratio in transplanted human hearts is not a sensitive indicator for the detection of early acute human cardiac allograft rejection. This may be due to a temporarily altered high-energy phosphate metabolism early after transplantation irrespective of rejection.
Copyright 1999 John Wiley & Sons, Ltd.