Background: Despite the major clinical complication of thromboembolic events after the Fontan procedure, there is no consensus regarding the optimal antithrombotic therapy. Novel tools to assess thrombogenicity are desirable to establish optimal thromboprophylaxis in this patient population. The Total Thrombus-formation Analysis System (T-TAS) was developed for the quantitative analysis of thrombus formation using microchips with thrombogenic surfaces. This study evaluated the utility of T-TAS in the assessment of thrombogenicity in pediatric Fontan patients.Methods and results: The participants included 20 consecutive Fontan patients who underwent cardiac catheterization and 30 healthy controls. Blood samples collected without and with antithrombotic therapy (aspirin or aspirin and warfarin) were used for T-TAS to compute the area under the curve (AUC) in the atheroma (AR10-AUC30) and platelet (PL18-AUC10) chips. T-TAS values showed that patients in the Fontan group without antithrombotic therapy had lower thrombogenicity than those in the control group (PL18-AUC10, median [interquartile range] 356 [313-394] vs. 408 [392-424]; AR10-AUC30, median [interquartile range] 1270 [1178-1351] vs. 1382 [1338-1421]). Aspirin and warfarin therapies signi cantly decreased PL18-AUC10and AR10-AUC30, respectively, compared with those of patients without antithrombotic therapy (P<0.001 for each comparison). Subgroup analysis divided by low (<9 mmHg) or high (≥ 9 mmHg) central venous pressure (CVP) showed that CVP affects the reduction in AR10-AUC30with antithrombotic therapy.Conclusions: T-TAS may be a useful tool for monitoring thrombogenicity and antithrombotic therapy in Fontan patients.

Background: Despite the major clinical complication of thromboembolic events after the Fontan procedure, there is no consensus regarding the optimal antithrombotic therapy. Novel tools to assess thrombogenicity are desirable to establish optimal thromboprophylaxis in this patient population. The Total Thrombus-formation Analysis System (T-TAS) was developed for the quantitative analysis of thrombus formation using microchips with thrombogenic surfaces. This study evaluated the utility of T-TAS in the assessment of thrombogenicity in pediatric Fontan patients. Methods and results: The participants included 20 consecutive Fontan patients who underwent cardiac catheterization and 30 healthy controls. Blood samples collected without and with antithrombotic therapy (aspirin or aspirin and warfarin) were used for T-TAS to compute the area under the curve (AUC) in the atheroma (AR10-AUC30) and platelet (PL18-AUC10) chips. T-TAS values showed that patients in the Fontan group without antithrombotic therapy had lower thrombogenicity than those in the control group (PL18-AUC10, median [interquartile range] 356 [313–394] vs. 408 [392–424]; AR10-AUC30, median [interquartile range] 1270 [1178–1351] vs. 1382 [1338–1421]). Aspirin and warfarin therapies significantly decreased PL18-AUC10and AR10-AUC30, respectively, compared with those of patients without antithrombotic therapy (P<0.001 for each comparison). Subgroup analysis divided by low (<9 mmHg) or high (≥ 9 mmHg) central venous pressure (CVP) showed that CVP affects the reduction in AR10-AUC30with antithrombotic therapy. Conclusions: T-TAS may be a useful tool for monitoring thrombogenicity and antithrombotic therapy in Fontan patients.