Platelet testing to guide aspirin dose adjustment in pediatric patients after cardiac surgery

Abstract Objectives Thrombosis is associated with increased morbidity and mortality in pediatric patients undergoing cardiac surgery. Although aspirin commonly is used for thromboprophylaxis, the utility of laboratory-based tests that assess aspirin efficacy have not been evaluated. We sought to determine the relationship between platelet aggregation testing and aspirin dose adjustment on thrombosis rates in this population. Methods Pediatric patients undergoing cardiac surgery who received aspirin and underwent platelet testing were studied retrospectively. Patients were excluded if they were treated with multiple agents or experienced thrombosis before the initiation of aspirin. Thrombosis events within 30 days after initiation of aspirin were recorded. Associations between aspirin responsiveness and thrombosis rate and aspirin dose adjustment and thrombosis rate were assessed with the use of multivariable logistic regression analysis. Results Suboptimal platelet response to aspirin was detected in 64 of 430 patients (15%) and thrombosis was detected in 11 patients (2.6%). Lack of aspirin responsiveness on initial testing was a significant risk factor for thrombosis ( P P P Conclusions Current practice of weight-based aspirin dosing may lead to subtherapeutic platelet inhibition in some children. Aspirin unresponsiveness is associated with increased risk of thrombosis after specific pediatric cardiac surgical procedures. Aspirin dose increase in unresponsive patients is associated with reduced risk of thrombosis.