Noninvasive monitoring of cardiac allograft rejection by intramyocardial electrogram recordings.

Rejection after cardiac transplantation was monitored in nine patients by control of intramyocardial electrogram (IMEG) recordings transmitted by an implanted telemetric pacemaker. Under immunosuppression with cyclosporin A and prednisolone, 33 out of a total of 119 endomyocardial biopsy specimens showed moderate rejection (infiltrate with myocytolysis). Twenty-nine of these rejection episodes could be correctly predicted from IMEG recordings with a voltage drop above 15% used as a criterion (sensitivity 87.9%). Eighty-three of 86 negative biopsy results corresponded to negative IMEG results (specificity 96.5%). In this group of patients, amplitude of body surface electrocardiograms was not useful for the diagnosis of rejection because of the broad range of spontaneous variation. Control of IMEG voltage amplitude appears to be more accurate than body surface electrocardiogram amplitude in the detection of rejection episodes. Thus the onset of rejection during biopsy intervals is more readily detected and treatment is instituted earlier. The method is suitable for ambulatory patient monitoring by the patient's local physician.