Abstract 18025: Systematic Screening is Necessary to Detect Post-operative Thrombosis and Evaluate Risk in Children Undergoing Cardiac Surgery: A Prospective Observational Study

Introduction: Postoperative thrombosis in children undergoing cardiac surgery with cardiopulmonary bypass (CPB) is a frequent, under-diagnosed and clinically detrimental complication. Methods: Pediatric patients were prospectively enrolled before surgery with CPB in an observational cohort study. Children <1 year old and cyanotic patients were oversampled. All subjects had serial lab assessment of hemostatic status and standardized vascular ultrasound for surveillance of post-operative thrombosis. Eligible non-enrolled patients were retrospectively reviewed as concurrent controls without study surveillance. All imaging findings underwent blinded adjudication to confirm the presence and clinical importance of identified thrombi. Results: Of 400 enrolled patients (54% males, 55% <1 year, 25% cyanotic), 398 (99%) completed the study, and 339 (85%) had protocol vascular ultrasound prior to or within 1 week of hospital discharge. Post-operative thrombosis was diagnosed in 99 study patients (25%) vs. 10% of the 1,019 control patients (p<0.001). Clinical evaluation alone missed 59% of all postoperative thrombi and 20% of clinically important thrombi. Multivariable factors associated with higher odds of postoperative thrombosis in study patients included 4 factors reflective of reduced heparin sensitivity and/or anticoagulation levels during CPB (Table). Postoperative thrombosis was associated with longer ICU stay (5 vs. 2 days, p=0.008), longer hospital stay (6 vs. 10 days, p<0.001), increased odds of reintervention or post-operation ECMO (OR: 2.7, p=0.005) and mortality (OR: 5.9, p=0.002). Conclusions: Given the poor performance of relying on clinical suspicion for detecting post-operative thrombosis, children <1 year old undergoing surgery with CPB should be systematically screened for thrombosis post-operatively. Individualization of thromboprophylaxis should consider both preoperative clinical factors and heparin sensitivity.