BACKGROUNDAcute allograft rejection in heart transplantation remains as one of the major complications. Obligatory graft surveillance is still achieved with the invasive and expensive endomyocardial biopsy (EMB). Our study aimed to study the use of intramyocardial electrograms combined with other noninvasive methods for the monitoring of acute rejection after human heart transplantation.

METHODSPermanent pacemakers were implanted in 58 patients undergoing heart transplantations. Intramyocardial electrograms (IMEG) were recorded periodically and the results were compared with those from EMBs. The R wave amplitude of the IMEG was used as the index value, the average R wave amplitude at the third week following transplantation was considered as the baseline, and a reduction of > 20% compared with the baseline was regarded as a positive result. EMB was performed in cases of positive IMEG results and also at other times. Other noninvasive methods were used to help the diagnosis. Acute rejection (AR) was defined as International Society of Heart-Lung Transplantation grade IIIA or higher.

RESULTSWe obtained 1231 IMEG records and 127 EMBs. Of the total 127 EMBs, 53 were positive, in which there were 42 IMEG positive results and 11 negative, while in the rest 74 negative EMBs, there were 9 IMEG positive results and 65 negative. The sensitivity of IMEG for the diagnosis of AR was 79.2%, and the specificity was 87.8%. The positive predictive value was 82.4% and the negative predictive value was 85.5%. Of the total of 1231 IMEG records, 51 were positive and 1180 were negative. Excluding 11 proved by EMB to be false negative, if the other 1169 were considered as no evidence of rejection, through the other noninvasive methods, AR diagnosed by this noninvasive monitoring strategy, the sensitivity was 79.2%, and the specificity was 99.2%. The positive predictive value was 82.4% and the negative predictive value was 99.1%.

CONCLUSIONSIMEG can be used as a noninvasive method for monitoring AR following heart transplantation. It is a continuous, safe and inexpensive method, and could reduce the need for EMB combined with other noninvasive methods, without reducing the detection of rejection.