Objectives. The purpose of this study was to assess the reliability of echocardiography in the noninvasive diagnosis of acute rejection in heart transplant recipients. Background. Although echocardiographic results seem to correlate well with allograft rejection, published data are limited and contradictory. Methods. In 130 transplant recipients, 1,400 serial echocardiograms were recorded within 24 h of endomyocardial biopsy. Increased wall thickness, myocardial echogenicity, pericardial effusion, shorter pressure half-time, isovolumetric relaxation time and a decrease in left ventricular ejection fraction were considered markers of rejection. Results. The distribution of echocardiographic markers revealed highly significant differences between bioptically graded moderate, mild and no rejection and between untreated and treated rejection episodes (both chi-square test, p <0.0001). Specificity was 98.6% for two markers, but sensitivity was good (80%) for only moderate rejection because of the large number of false negatives in untreated patients with mild rejection. In untreated patients, there was a highly significant difference in the number of echocardiographic criteria between a benign and nonbenign outcome (chi-square test, p <0.0001). In treated patients, the significant difference in the variation in echocardiographic criteria between favorable and unfavorable responses after 1 week was more pronounced after 2 weeks (t test, p <0.01 vs. <0.081). Diastolic indexes and pericardial effusion at 2 weeks seemed to be predictive of therapeutic response. Conclusions. Poor sensitivity to mild rejection indicates that serial echocandiography cannot supplant endomyocardial biopsy in the early diagnosis of acute rejection, but it seems to be a reliable noninvasive means of identifying acute rejection requiring intensified immunosuppressive therapy and of evaluating outcome.
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