Background and methods: In a prospective protocol for noninvasive diagnosis of acute cardiac rejection, 83 routine endomyocardial biopsies, followed each time by the analysis of signal-averaged electrocardiography and by a cardiac Doppler echocardiographic study, were performed in 18 heart transplant recipients. The follow-up time was 5 +/- 3.6 months. To detect noninvasively acute cardiac rejection, we compared biopsy findings with the presence of late potentials at signal-averaged electrocardiography and with two diastolic indexes, pressure half-time, and isovolumic relaxation time obtained from Doppler echocardiographic study.
Results: Thirteen acute rejection crises requiring modification of immunosuppression were diagnosed by means of endomyocardial biopsy. This clinically relevant acute cardiac rejection was associated with the presence of late potentials in 69% of cases and with the presence of pressure half-time < or = 55 msec and isovolumic relaxation time < or = 60 msec in 69% and 62% of cases, respectively. Sensitivity and specificity were as follows: for late potentials, 69% and 71%; for pressure half-time < or = 55 msec, 69% and 76%; for isovolumic relaxation time < or = 60 msec, 62% and 83%, respectively. The presence in a single patient of at least one abnormal parameter showed a sensitivity of 100% and a specificity of 60% in detecting important rejection.
Conclusions: These data support the use of combined signal-averaged electrocardiography and Doppler echocardiographic study of the left ventricular diastolic function in the screening of acute cardiac rejection. Such results can suggest when endomyocardial biopsy should be performed, with the reliance that a normal noninvasive study highly excludes the presence of acute cardiac rejection requiring intensified immunosuppression.