Background: Acute cardiac allograft rejection is associated with early diastolic dysfunction. The development of chronic rejection is dependent on the frequency and severity of acute rejection episodes. Therefore, early diagnosis and therapy influence long-term survival significantly. For the first time, acoustic quantification, a new echocardiographic technology for on-line measurement of cardiac volumes and their changes, facilitates quantitative assessment of systolic and diastolic function noninvasively.
Methods: Since May 1996, all consecutive patients after cardiac transplantation (n = 94) underwent 475 endomyocardial biopsies and the same number of echocardiographic studies within 6 hours after biopsy before the histological results were available.
Results: Nineteen patients showed 23 episodes of acute rejection (ISHLT > or = 2). There was a significant decrease in left ventricular peak filling rate [PFR: end-diastolic volume (EDV)/ second) as a parameter of diastolic function during rejection (2.9 +/- 0.4, n = 23) as compared to PFR measured under nonrejection status (4.5 +/- 0.8; n = 452; p < 0.0001). Most importantly we found that in these 19 patients showing rejection, the PFR was normal in the last examination before rejection, but was significantly reduced during rejection (2.9 +/- 0.4 vs 4.5 +/- 0.7; n = 23, p < 0.0001). After successful rejection therapy, PFR again normalized in all patients, with the exception of 1 patient with steroid-refractory humoral rejection. We calculated sensitivity and specificity for several cutpoints for the event "first rejection" in 15 patients and plotted them in a receiver operating characteristic curve, showing that a PFR > or = 4.0 EDV/second is never associated with treatable rejection. A decrease of PFR of more than 18% from its prevalue of the last biopsy with no rejection increases the accuracy for the diagnosis of rejection significantly.
Conclusions: We conclude that diastolic dysfunction during acute cardiac allograft rejection can be accurately detected by noninvasive measurement of peak filling rate with acoustic quantification echocardiography. Monitoring of this parameter provides reliable discrimination between treatable and nontreatable rejection.