Background. At our transplant center, cardiac allograft recipients undergo transplantation following a negative IgG anti-human globulin (AHG) crossmatch (XM). Flow cytometry crossmatching (FCXM) is a more sensitive XM procedure than the AHG XM procedure, yet there is limited information regarding the clinical relevance of FCXM to cardiac allograft outcome. Methods. FCXM was performed retrospectively using the pretransplant sera from 140 recipients of primary cardiac allografts who underwent transplantation after AHG-IgG-NEG XM. The FCXM results were correlated to posttransplant rejection and patient survival. Results. All of the patients were auto-XM-NEG. Twenty-two of 140 patients (16%) displayed IgG(+) FCXM and had a significantly poorer 1-year survival rate than did 57 of the FCXM-NEG recipients (68% vs. 86%, P
