Has the 2004 revision of the International Society of Heart and Lung Transplantation grading system improved the reproducibility of the diagnosis and grading of cardiac transplant rejection?

We compared the interobserver reproducibility of the 1990 and 2004 International Society for Heart and Lung Transplantation (ISHLT) grading system for cardiac rejection. The 2004 ISHLT grading system for cardiac allograft rejection did not improve reproducibility partly due to pathologists' disagreement in diagnosing Grades 1B/1R and 3A/2R rejection. To achieve better reproducibility, better criteria for defining 1B/1R vs. 3A/2R rejection and markers of myocyte injury are needed.