Abstract 11665: Early Aspirin Use, Rejection, and the Development of Cardiac Allograft Vasculopathy Following Orthotopic Heart Transplantation

Background:We previously observed early aspirin (ASA) use after orthotopic heart transplantation (OHT) to be associated with lower rates of moderate to severe cardiac allograft vasculopathy (CAV). Antibody-mediated rejection (AMR) and acute cellular rejection (ACR) are important risk factors for CAV. As ASA has anti-inflammatory and antithrombotic actions, we hypothesized that the inverse association between ASA use and CAV incidence may be most pronounced in patients with allograft rejection.Methods:Patients receiving OHT at a single center (N=120) were categorized by the presence of early ASA use post-transplant (ASA treatment >6 months in the first year) and the presence of ACR and/or AMR during 5-year follow-up. Propensity scores for ASA treatment were estimated using boosting models and applied by inverse probability of treatment weighting. The association between ASA use and time to angiographic moderate/severe CAV (International Society for Heart and Lung Transplantation grade ? 2) was investigated and interaction tested with rejection status.Results:Patients with rejection (N=77) were younger and less likely hypertensive with no imbalance in aspirin use. Patients with both AMR and ACR had higher rates of CAV >2 at 5 years than those with either isolated AMR or ACR or no rejection (24.0 vs 14.9 v 5.3%; ptrend=0.028). Among patients with rejection, ASA therapy was associated with significantly lower rates of CAV >2 (3.3 vs 30.1%; p=0.001; HRadj0.07; 95% CI 0.01-0.52; Fig.), whereas ASA therapy was not associated with lower rates of CAV in patients with no rejection (5.6 vs 5.3%; p=0.900; pinteraction=0.094).Conclusions:Early ASA use after OHT was associated with lower rates of moderate to severe CAV among patients with allograft rejection. This observation supports the need for a prospective randomized evaluation of ASA therapy after heart transplantation.