There are few data to guide aspirin therapy to prevent shunt thrombosis in infants. We aimed to determine if aspirin administered at conventional dosing in shunted infants resulted in ≥50% arachidonic acid (AA) inhibition in short and midterm follow-up using thromboelastography with platelet mapping (TEG-PM) and to describe bleeding and thrombotic events during follow-up. We performed a prospective observational study of infants on aspirin following Norwood procedure, aortopulmonary shunt alone, or cavopulmonary shunt surgery. We obtained TEG-PM preoperatively, after the third dose of aspirin, at the first postoperative clinic visit, and 2-8 months after surgery. The primary outcome was the proportion of subjects with ≥50% AA inhibition on aspirin. All bleeding and thrombotic events were collected. Of 24 infants analyzed, 13% had ≥50% AA inhibition at all designated time points after aspirin initiation; 38% had ≥50% AA inhibition after the third aspirin dose of aspirin, 60% at the first postoperative clinic visit, and 26% 2-8 months after surgery. Bleeding events occurred in eight subjects, and two had a thrombotic event. Bleeding events were associated with greater AA inhibition just prior to starting aspirin (p = 0.02) and after the third dose of aspirin (p = 0.04), and greater ADP inhibition before surgery (p = 0.03). The majority of infants failed to consistently have ≥50% AA inhibition when checked longitudinally postoperatively. Preoperative TEG-PM may be useful in identifying infants at higher risk of bleeding events on aspirin in the early postoperative period. Further research is needed to guide antiplatelet therapy in this population.
Keywords: Blood; Coagulation/anticoagulation; Congenital heart disease.