The standard of care in adult heart transplant recipients has been to perform periodic endomyocardial biopsies for surveillance for rejection. Because of the risks and discomforts associated with the biopsy procedure, a non-invasive test (AlloMap) based on gene-expression profiling of peripheral blood was developed and introduced in 2005 to identify heart transplant recipients who have a low probability of rejection at the time of protocol surveillance testing. The schedule of AlloMap surveillance testing has been derived from the customary timing of surveillance biopsies: e.g. at 1 to 2 month intervals for patients who are 6 and 12 post-transplantation, and at 3, 4 or 6 months after the first year post-transplantation.
In the large multicenter IMAGE (Invasive Monitoring Attenuation by Gene Expression Profiling) 602 patients in the United States who had undergone cardiac transplantation at least 6 months prior were randomized 1:1 to either surveillance with routine biopsy or AlloMap testing. Patients in both groups were also monitored with echocardiography. A primary outcome event was defined as an episode of rejection with hemodynamic compromise, graft dysfunction due to other causes, death or retransplantation. Over a median follow-up period of 19 months, 297 patients who were monitored with AlloMap and 305 patients who underwent routine biopsies had similar 2-year cumulative rates of events (14.5% and 15.3%, respectively; hazard ratio with gene-expression profiling, 1.04; 95% confidence interval, 0.67 to 1.68).
This Outcomes AlloMap Registry (OAR) study is designed to collect similar clinical outcomes information as studied in IMAGE, in a larger cohort of patients (approximately 2000) followed for up to 5 years. At each routine clinic visit, key clinical features such as rejection surveillance management schedules, testing results (e.g. blood levels of immunosuppressive agents), and AlloMap scores will be collected. This larger and longer term follow-up dataset is intended to enable further elucidation, through analyses techniques such as multivariate Cox proportional hazards models, of the surveillance management features which may be associated or contribute to the most favorable long term outcomes of the heart recipients.
