Abstract
Background: Heart transplant rejection is a multifactorial phenomenon routinely assessed using endomyocardial biopsy. Recently, efforts have been made to identify less invasive and cost-effective biomarkers for predicting graft rejection. Objectives: This study evaluated serum CK-MB levels in heart transplant patients and examined their relationship with the grading of graft rejection. Methods: In a prospective cohort study, 92 biopsy specimens from heart transplant patients were analyzed at Tehran's Rajaie Cardiovascular Medical and Research Center during 2022. Rejection grades, plasma CK-MB levels, and their relationship were investigated. Results: The mean age (standard deviation) of the patients was 36.70 (9.59) years, with 60.9% being male. Regarding graft rejection grades, 16.3% were grade 0R, 46.7% had Quilty effect (QE), 32.6% were grade 1R, and 4.3% were grade 2R. The mean (standard deviation) serum CK-MB levels for grades 0R, QE, 1R, and 2R were 17.14 (16.46), 12.39 (7.52), 26.77 (22.97), and 29.50 (7.94) ng/L, respectively (P = 0.046). The sensitivity of CK-MB for detecting grade 1R and 2R graft rejection was 56.7% and 75%, respectively, while its specificity for detecting grade 0R was 80%. A significant correlation was observed between increased serum CK-MB levels and transplant rejection grades (P < 0.001). Most cases of grade 0R had negative CK-MB serum levels (< 24 IU/L), with a higher frequency of positive CK-MB in grade 1R compared to grade 0R and in grade 2R compared to grade 1R. Conclusions: While elevated serum CK-MB levels in heart transplant patients may indicate graft rejection, the inconsistency of CK-MB levels with graft rejection grades suggests that endomyocardial biopsy and histopathological examination remain the gold standard for determining graft rejection grades.