Diagnosis of early cardiac transplant rejection by fall in evoked T wave amplitude measured using an externalized QT driven rate responsive pacemaker.

Reliable diagnosis of cardiac allograft rejection is at present only possible using endomyocardial biopsy. We have serially measured epicardial evoked T wave amplitude during ventricular pacing with an externalized QT driven rate responsive pacemaker telemetered to a TP2 analyzer in 13 patients (12 males) followed for 19 (14-26) days after transplantation. A total of 228 records were analyzed. Rejection was defined on endomyocardial biopsy. On 17 of the 31 occasions on which biopsy was performed during the study, specimens showed significant (moderate) rejection. In 11 patients the initial biopsy proven rejection episode was associated with a significant fall in the evoked T wave amplitude from 1.3 (0.7-2.3) mV to 0.6 (0.5-1.8) mV (P less than 0.005), which began 2 (1-4) days earlier. One patient with uncontrolled diabetes mellitus had no change in evoked T wave amplitude during rejection. The evoked T wave amplitude did not fall in the absence of histologic rejection. These results suggest a noninvasive method for detecting cardiac rejection, which appears both sensitive (92%) and specific (100%) in the first rejection episodes.