Noninvasive monitoring of rejection therapy based on intramyocardial electrograms after orthotopic heart transplantation. Initial experience with 14 cases

Abstract

Despite the use of increasingly specific immunosuppressive therapy, rejection remains the leading cause of death in cardiac transplant patients. Endomyocardial biopsy (EMB) is the gold standard for early detection and monitoring of cardiac transplant rejection. However, this approach is invasive and not suitable for routine use. A noninvasive alternative for monitoring cardiac transplant patients uses the analysis of the ventricular evoked response (VER) obtained by programmed electrical stimulation. Rejection-sensitive parameters (RSP) and infection-specific parameters (ISP) are extracted from changes in the slope of the T-wave and from the duration of repolarization, respectively. For the analysis of intramyocardial electrograms, separate left and right ventricular pacing at a rate of 100 beats/min and lasting 60 s is required, following the same protocol. From year 2000, telemetric pacemakers were implanted in 14 patients undergoing heart transplantation at this institution. A total of 95 endomyocardial biopsies and 275 ventricular evoked response measurements were carried out. Five out of 6 cases with significant rejection were correctly identified by RSP values below a threshold of 98% (sensitivity=80%, specifity=50%, negative predictive value=97%, positive predictive value=11%; P<0.002). Of the EMBs, 45% could have been saved if the diagnosis model had been used to indicate need for EMB. Noninvasive cardiac graft monitoring can reduce the need for surveillance biopsies and may offer a tool to optimize immunosupressive therapy after heart transplantation. Rejection grade 2 or higher can safely be detected.