OBJECTIVEAssess the clinical implication of microvasculopathy detected by endomyocardial biopsy samples in patients post heart transplantation.

METHODSLight microscopic evaluations were performed in 278 endomyocardial biopsies harvested from 64 patients post heart transplantation for more than one year, microvasculopathy was defined as stenotic endothelial and/or medial disease.

RESULTSThe patients with stenotic microvasculopathy were younger than those without microvasculopathy (40.7 ± 15.9 vs. 49.4 ± 8.7, P < 0.05). The mean score of acute cellular rejection (0.83 ± 0.39 vs. 0.37 ± 0.32, P < 0.01) and the numbers of ≥ grade II acute rejection (0.84 ± 0.16 vs. 0.23 ± 0.10, P < 0.01) were significantly greater in stenotic microvasculopathy group compared to those of non-stenotic group. Multivariate regression analysis confirmed that stenotic microvasculopathy is the independent risk factor for the mean acute rejection score (OR = 3.40, 95%CI, 4.62 - 193.07, P < 0.01), but not for the Quilty lesion, coronary heart disease of donor, diabetes mellitus. Angiographically confirmed coronary vasculopathy and cardiac dysfunction (χ(2) = 0.94, P > 0.05 and χ(2) = 2.90, P > 0.05) were similar between microvasculopathy group and non-microvasculopathy group.

CONCLUSIONPost heart transplantation microvasculopathy is an immune-mediated phenomenon and associated with higher mean score of acute cellular rejection and higher numbers of ≥ grade II acute rejection but was not the prognostic risk factor for coronary vasculopathy and function reduction after heart transplantation.