Echo rejection score: new echocardiographic approach to diagnosis of heart transplant rejection.

OBJECTIVE The gold standard test in the diagnosis of heart transplant rejection is right ventricular (RV) myocardial biopsy, which is an invasive, time-consuming, expensive method. In an effort to find a reliable method to minimise the sequential use of myocardial biopsy, we assessed the main echocardiographic indices for the detection of allograft rejection. MATERIALS AND METHODS Fifty myocardial specimens were examined in this prospective study, which assessed the prominent echocardiographic parameters propounded by previous studies as indicators of rejection. Prior to biopsy, all the patients underwent preoperative transthoracic echocardiography. The accuracy of the echocardiographic indices was compared with that of myocardial biopsy indices as the gold standard. At three myocardial segments, namely, RV base, interventricular septal (Sep) base and lateral left ventricular (Lat) base, peak systolic strain (RV-S, Lat-S and Sep-S) was measured. In addition, time to systole (TS) was measured at the same three segments, yielding the three variables of RV-TS, Sep-TS and Lat-TS. RESULTS Our logistic regression model revealed that the four factors of Lat-S (%), Sep-TS (ms), posterior wall thickness (PWT; mm) and left ventricular mass index (LVMI; g m(-2)) could denote heart transplant rejection. We devised a new index, the echo rejection score, using the following formula: [(PWT+LVMI)-(Lat-S+Sep-TS)]. This new formula has an area under a curve of 0.932 and a cut-off point of 0; it yields a sensitivity of 100.0%, specificity of 71.0%, positive predictive value of 67.9% and a negative predictive value of 100.0%. If the echo rejection score is >0, there is a 67.9% possibility that a cardiac transplant patient is presenting with allograft rejection, while a score < or =0 denotes a 100% improbability of rejection. CONCLUSION Our proposed method for screening patients at risk of acute cardiac rejection with echo rejection score showed a good sensitivity in detection of graft rejection. However, further study is required to determine if it can be used as an adjunct to the myocardial biopsy.