Ashraf Abdo

Myocardial ischemic-fibrotic injury after human heart transplantation is associated with increased progression of vasculopathy, decreased cellular rejection and poor long-term outcome.

OBJECTIVES We sought to assess the influence of peritransplant ischemia and fibrosis on the development of allograft vasculopathy, acute cellular rejection and long-term outcome. BACKGROUND Allograft vasculopathy is a common long-term complication of cardiac transplantation. One of the potential risk factors is peritransplant allograft ischemia. METHODS One hundred forty heart transplant recipients had baseline and one-year intravascular ultrasound analysis done to assess the progression of allograft vasculopathy. Serial endomyocardial biopsies were evaluated for cellular rejection, vascular rejection, ischemia and fibrosis. Based on histology, patients were classified into one of the following groups: nonischemic (n = 32), ischemia (n = 24), fibrosis (n = 62) or vascular rejection (n = 22). Three-color flow cytometry crossmatching (FCXM) was used to assess donor-specific human lymphocyte antigens (HLA) sensitization. Long-term outcome of patients in each group was assessed by estimating incidence of graft failure or deaths over a seven-year follow up. RESULTS Patients in the fibrosis group had the lowest incidence of donor-specific HLA sensitization (40%, p = 0.008) and lowest average episodes of cellular rejection (1.7 +/- 1.4, p = 0.04), but they had increased coronary vasculopathy progression (change in coronary intimal thickness = 0.59 +/- 0.28 mm, p < 0.0001) and poor seven-year event-free survival (49%, p = 0.01). CONCLUSIONS The development of fibrosis after cardiac transplantation is associated with advanced coronary vasculopathy, although a low incidence of acute cellular rejection is noted, suggesting the presence of nonimmune mechanisms in mediating the pathogenesis of allograft vasculopathy.

Does acute cellular rejection correlate with cardiac allograft vasculopathy

BACKGROUND Previous studies of the association between acute cellular rejection and cardiac allograft vasculopathy (CAV) have yielded conflicting conclusions. We explored a possible association between acute cellular rejection and the extent of CAV, and we found a potential confounding variable that may obscure such an association. METHODS We investigated 140 patients (mean age, 51 +/- 11 years) who underwent serial intravascular ultrasound examinations at baseline and at 1 year after heart transplantation to assess CAV as change in maximal intimal thickness (CMIT). Patients were classified according to the presence or absence of biopsy-proven myocardial fibrosis. We used a standard biopsy-scoring system and a novel biopsy-scoring system, developed in our institution, to assess acute cellular rejection. Using univariate analysis, we found that CMIT was not associated with acute cellular rejection in the overall patient population (n = 140). However, we observed a correlation between CMIT and acute cellular rejection (standard method, r = 0.30, p = 0.01; novel method, r = 0.51, p < 0.0001) in patients who had no evidence of ischemic injury or fibrosis in their biopsy specimens (n = 57). Step-wise multiple regression showed that the rejection score derived from our novel method was associated more closely with the CMIT than was that derived from the traditional method. CONCLUSIONS This data indicate that the presence of myocardial fibrosis masks an actuarial association between acute cellular rejection and the development of de novo allograft vasculopathy. As previously suspected, myocardial fibrosis is a marker for non-immune-mediated graft injury independently associated with an increased incidence of CAV.

Donor Spontaneous Intracerebral Hemorrhage Is Associated With Systemic Activation of Matrix Metalloproteinase-2 and Matrix Metalloproteinase-9 and Subsequent Development of Coronary Vasculopathy in the Heart Transplant Recipient

Background—Matrix metalloproteinase (MMP)-2 and MMP-9 have been shown to play a role in the progression of hemorrhagic stroke. We hypothesized that donor intracerebral hemorrhage (ICH) is associated with activation of the metalloproteinases before transplantation that play a key role in the subsequent development of transplant vasculopathy. Methods and Results—We evaluated mRNA expressions of MMP-2 and MMP-9 in donor spleen lymphocytes (before transplantation) and in heart biopsies at 1 week after transplantation in 20 recipients from ICH donors and 20 recipients from trauma donors. Patients underwent serial coronary intravascular ultrasound, and interstitial myocardial fibrosis was quantified at 1 year. The baseline characteristics were similar except for increased donor age in the ICH group. Heart biopsies from the ICH group showed significant increased expression of MMP-2 (17-fold, P <0.0001) and MMP-9 (20-fold, P <0.0001) compared with the trauma group. Furthermore, the ICH group showed 1.8-fold (P =0.016) increased mRNA expression of MMP-2 and 1.7-fold (P =0.015) increased mRNA expression of MMP-9 in the donor spleen lymphocytes, suggesting the presence of systemic activation of metalloproteinases before transplantation. At 1 year, the ICH group showed increased myocardial fibrosis and accelerated coronary vasculopathy. Using multivariate regression analysis, MMP-9 was found to be associated with increased risk for vasculopathy independent of donor age (OR, 2.41; P =0.01; 95% CI, 1.24 to 4.69). Conclusions—This is the first report to describe systemic activation of MMP-2 and MMP-9 in donors with intracerebral hemorrhage and subsequent development of allograft vasculopathy.

Computerized scoring of histopathology for predicting coronary vasculopathy, validated by intravascular ultrasound

BACKGROUND Allograft coronary vasculopathy results from a complex interplay between immunologic and non-immunologic factors. We devised a computerized biopsy scoring method based on histopathology to predict the development of coronary vasculopathy. METHODS One hundred forty heart transplant recipients underwent serial intravascular ultrasound analysis at baseline (within 1 month) and at 1 year after transplantation and were evaluated for development of coronary vasculopathy (change in coronary maximal intimal thickness, CMIT). We evaluated serial endomyocardial biopsy specimens for cellular rejection, vascular rejection, ischemia, and fibrosis. In a mathematical model, we computed a biopsy score in each patient based on the duration and severity of histopathology. RESULTS We found a significant correlation between biopsy score (RY) and progression of coronary vasculopathy (r = 0.54, p = 0.001). Using a sensitivity analysis method, an RY value of > or =560 predicted development of coronary vasculopathy with a sensitivity of 86%, specificity of 62%, and diagnostic accuracy of 80%. Compared with patients with low-risk biopsy scores (RY < 560, n = 37), patients with high-risk biopsy scores (RY > or = 560, n = 103) had increased progression of coronary vasculopathy (CMIT, 0.59 +/- 0.29 vs 0.19 +/- 0.10 mm, p < 0.001) and worse 7-year event-free survival (60% vs 91%, p = 0.01). CONCLUSION The biopsy score is an effective method for predicting the development of coronary vasculopathy and for predicting outcome in cardiac transplant recipients.

Impact of Donor Spontaneous Intracranial Hemorrhage on Outcome after Heart Transplantation

Donor cause of death has been suggested to have a significant impact on cardiac transplant morbidity and mortality. Our objective was to evaluate the impact of donor spontaneous intracranial bleeding on clinical outcome after heart transplantation. A group of 160 recipients underwent cardiac transplantation from donors with spontaneous intracranial bleeding (ICB group). These were compared with 197 recipients who were transplanted from trauma donors (Trauma group). A higher 4‐year mortality rate was noted in the ICB group (24% vs. 14%, p = 0.015). ICB as a cause of donor death was an independent predictor of recipient mortality (adjusted hazard ratio 2.02, 95% CI 1.27–3.40, p < 0.0001). Compared with the Trauma group, the ICB group had an increased incidence of post‐transplant graft dysfunction during the first week of transplant (10% vs. 3%, p = 0.007), and higher incidence of interstitial myocardial fibrosis on their endomyocardial biopsies within 4 weeks of transplant (21% vs. 9%, p = 0.0012). There was a trend towards an increased rate of allograft vasculopathy in the ICB group (competing risks adjusted hazard ratio 1.39, 95% CI 0.90–2.13, p = 0.14).

Systemic Up‐Regulation of Angiotensin II Type 1 Receptor in Cardiac Donors with Spontaneous Intracerebral Hemorrhage

Donor spontaneous intracerebral hemorrhage (ICH) is a potential risk factor for morbidity and mortality after cardiac transplantation. We hypothesized that donor ICH is associated with systemic up‐regulation of angiotensin II receptor type 1 (AT1R). We evaluated mRNA expression of AT1R and AT2R in donor spleen lymphocytes and in heart biopsies from 20 recipients of hearts from donors with spontaneous ICH which were compared with 20 recipients from trauma donors. Heart biopsies showed 4.7‐fold increased mRNA expression of AT1R (p < 0.0001) in the ICH group compared with the Trauma group. The ICH group also showed 2.6‐fold (p < 0.01) increased mRNA expression of AT1R in the donor spleen lymphocytes, suggesting the presence of systemic activation before transplantation. At 1 year, the ICH group had increased coronary vasculopathy by vascular ultrasound. Using multivariate regression analysis, mRNA expression of AT1R in the donor spleen lymphocytes was found to be a strong independent predictor of transplant vasculopathy (odds ratio = 4.397, CI = 1.243–15.553, adjusted p = 0.02). This is the first report to describe splenic up‐regulation of AT1R in the presence of spontaneous ICH and its association with subsequent development of transplant vasculopathy.

HLA alloantibodies and time of death in cardiac transplantation

For some time now it has become clear at our program that a positive flow cytometry crossmatch (FCXM) is associated with a degree of morbidity and mortality. Here we have examined this issue again to determine what impact these anti-donor HLA antibodies might have on the time of death in failed transplants. Of 876 total transplants available for analysis, 637 continue to survive (72.7%), 63 (7.2%) were lost within 90 days, 76 (8.7%) were lost between 90 days and 3 years, and 100 (11.4%) greater than 3 years post-transplant. As seen in the table, when 584 patients with FCXM results were stratified by FCXM as negative, HLA class I positive (T&B reactive) and class II positive (T negative, B cell positive), there was a significant difference observed with class I and class II reactions associated with increased early and intermediate losses when compared to the negatives. We have also previously observed that hearts from donors who died due to a cerebrovascular accident (CVA) seem particularily sensitive to these antibodies. With these donors, almost 30% of the class I positive transplants were lost within the first 90 days. The amount of antibody reactivity of the FCXM measured in molecules of fluorescence binding to the donor cells also differed among these groups. The mean increase in fluorescence over controls was 562 for survivors, 3491 for 90 day deaths, 1102 for intermediate (90 days-3 years), and 10,562 molecules for late deaths (p 0.0001). It seems that HLA antibodies identified at the time of transplant may be assoicated not only with early but also late death in cardiac transplantation.