Early aspirin use, allograft rejection, and cardiac allograft vasculopathy in heart transplantation.

BACKGROUND: Early aspirin (ASA) use after orthotopic heart transplantation (OHT) has been associated with lower rates of cardiac allograft vasculopathy (CAV). 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 2004-2010 (n = 120) were categorized by early ASA use post-transplant (ASA use for > 6 months in the first year) and the presence of biopsy-defined acute cellular rejection (ACR) and/or antibody-mediated rejection (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 moderate/severe CAV (ISHLT ≥ 2) was investigated. RESULTS: Among patients with ACR or AMR, ASA therapy was associated with significantly lower rates of CAV≥ 2 (3.3 vs. 30.1%; P = .001; HRadj .07; 95% CI .01-.52), whereas ASA therapy was not associated with lower rates of CAV in patients with no rejection (5.6 vs. 5.3%; P = .90; HRadj 1.26; 95% CI .08-20.30; pinteraction  = .09). CONCLUSIONS: Early ASA use after OHT was associated with lower rates of moderate to severe CAV only in those patients with episodes of allograft rejection.

Early aspirin use and the development of cardiac allograft vasculopathy.

BACKGROUND: Cardiac allograft vasculopathy (CAV) remains a leading cause of morbidity and mortality after orthotopic heart transplantation (OHT). Little is known about the influence of aspirin on clinical expression of CAV. METHODS: We followed 120 patients with OHT at a single center for a median of 7 years and categorized them by the presence or absence of early aspirin therapy post-transplant (aspirin treatment ≥6 months in the first year). The association between aspirin use and time to the primary end-point of angiographic moderate or severe CAV (International Society for Heart and Lung Transplantation grade ≥2) was investigated. Propensity scores for aspirin treatment were estimated using boosting models and applied by inverse probability of treatment weighting (IPTW). RESULTS: Despite a preponderance of risk factors for CAV among patients receiving aspirin (male sex, ischemic heart disease as the etiology of heart failure, and smoking), aspirin therapy was associated with a lower rate of moderate or severe CAV at 5 years. Event-free survival was 95.9% for patients exposed to aspirin compared with 79.6% for patients without aspirin exposure (log-rank p = 0.005). IPTW-weighted Cox regression revealed a powerful inverse association between aspirin use and moderate to severe CAV (adjusted hazard ratio 0.13; 95% confidence interval 0.03-0.59), which was directionally consistent for CAV of any severity (adjusted hazard ratio 0.50; 95% confidence interval 0.23-1.08). CONCLUSIONS: This propensity score-based comparative observational analysis suggests that early aspirin exposure may be associated with a reduced risk of development of moderate to severe CAV. These findings warrant prospective validation in controlled investigations.