Myocardial high-energy phosphate metabolism in heart transplant patients is temporarily altered irrespective of rejection

A reliable, sensitive, non-invasive alternative for transvenous endomyocard ial biopsy in detecting cardiac allograft rejection is desirable for optima l management of heart transplant patients. To establish whether P-31 magnet ic resonance spectroscopy can become a non-invasive tool for detecting card iac allograft rejection, the cardiac high-energy phosphate metabolism of hu man heart transplants was serially examined in 13 patients by means of P-31 MRS from post-operative day 13 to day 294, and compared with histologic ev aluation of endomyocardial biopsies. Biopsy scores of 2 or higher, accordin g to the Working Formulation criteria of Billingham et al., were considered to indicate rejection. Logistic regression, which was corrected for differ ences between the individual patients and the time after transplantation, s howed no significant correlation between the occurrence of histologically d etected rejection and the PCr:ATP ratio. However, using an analysis of vari ance, the PCr:ATP ratios of non-rejecting cases obtained within 50 days aft er transplantation (mean: 27 +/- 11 days) appeared to be significantly diff erent from those obtained after post-operative day 50 [0.95 +/- 0.17 (n = 2 5) vs 1.17 +/- 0.17 (n = 32), mean +/- SD; p < 0.01]. No significant differ ence was observed between the PCr:ATP ratios obtained 100 days after transp lantation (mean: 162 +/- 52 days) and the PCr:ATP ratios in the hearts of h ealthy 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 hea rts is not a sensitive indicator for the detection of early acute human car diac allograft rejection. This may be due to a temporarily altered high-ene rgy phosphate metabolism early after transplantation irrespective of reject ion. Copyright (C) 1999 John Wiley & Sons, Ltd.