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.