Heart graft monitoring by the ventricular evoked response

Monitoring of the negative slew rate of the evoked T wave has been proposed as a noninvasive diagnostic tool to follow heart transplant recipients. Th e clinical contribution of this measurement on telemetrically recorded, pac ed unipolar ventricular electrograms was evaluated in the detection of grad e 3 acute allograft rejection. Thirteen patients undergoing heart transplan tation received a DDD pacemaker connected to two epimyocardial leads. Elect rograms were recorded and digitized after each endomyocardial biopsy(EMB). The maximum slew rate of the descending slope of the repolarization phase ( RSP) was extracted and normalized. A 20% downward shift of RSP from the ref erence value was considered abnormal. Results of signal processing were bli nded during the first 6 months. Eleven patients completed the 6 months blin ded period and two patients died. A total of 101 EMB were graded according to the International Society for Heart and Lung Transplantation classificat ion. Grade 3 was assigned to 9 EMB. A significant difference wets found bet ween RSP values measured during grade 3 rejection episodes and other RSP va lues (P < 0.001). A diagnostic model consisting of a single threshold test confirmed the ability of RSP to predict significant signs of rejection on E MB (P < 0.0001). The sensitivity of RSP in detecting grade 3 rejections was 100%, specificity was 81%, negative predictive value 100%, and positive pr edictive value 35%. The use of RSP as a noninvasive monitoring tool to pose the indication for a biopsy would avoid 73% of EMB. Monitoring of transpla nted hearts based on the analysis of the ventricular evoked response is pro mising and may markedly reduce the number of EMB.