C4d Immunostaining Is an Independent Predictor of Graft Dysfunction, Cardiac Allograft Vasculopathy and Death in Heart Transplant Recipients

Abstract

Purpose Antibody-mediated rejection (AMR) occurs in 10-20% of patients post heart transplant (HT), and is associated with hemodynamic instability, rejection, coronary allograft vasculopathy (CAV) and death. C4d immunostaining, histology, allograft dysfunction and presence of donor specific antibodies are used in the diagnosis of AMR. This study aimed to determine if C4d staining has prognostic significance in patients post-HT. Methods and Materials Consecutive patients receiving an endomyocardial biopsy between July 2007-June 2008 were selected. Left ventricular function, angiography, episodes of antibody and cellular rejection (CMR) and death were noted. Subsequent biopsies after enrollment were reviewed. Immunostaining for C4d deposition was performed on paraffin-embedded tissue using an anti human antibody (rabbit polyclonal, [ALPCO, Salem, NH]), and were graded from 0-3. We used Cox proportional models and recurrent events analysis to evaluate the association between C4d staining (time-varying covariate) and mortality, graft dysfunction, CAV and episodes of ≥2R-CMR. Results We analyzed 2525 biopsy specimens from 217 patients. The average age of patients were 45 ± 13 years at transplant (70% were males). During a mean follow up of 4.5 ± 2 years, 35 died, 49 patients had LV dysfunction, 7 had CAV and 51 patients had a total of 95 episodes of CMR. On multi-variable analysis, C4d staining was a significant predictor of graft dysfunction (HR 1.64; 95% CI 1.14-2.36) and death (HR 2.38; 95% CI 1.1-2.6) after adjusting for donor age and ischemic time. In univariable analysis, C4d staining was associated with higher risk of CAV (HR 2.4, 95% CI 1.04-5.4). C4d staining was not associated with episodes of CMR (HR 1.16; 95% CI, 0.84-1.6) after adjusting for recipient’s age, sex and transplant year. Conclusions Asymptomatic C4d immunostaining was a significant predictor of graft dysfunction, CAV and death and was not associated with subsequent episodes of CMR.