045 Silent Thromboembolic Events in Adults After the Fontan Operation

Abstract

Thromboembolic complications have been noted after the Fontan operation. However, the prevalence of silent events among the adult population is not known. The objective of this study is to determine the prevalence of “silent” intracardiac thrombus and thrombus in the Fontan and pulmonary circulations among adults after the Fontan operation using a new dual energy CT protocol. All post Fontan patients attending the Pacific Adult Congenital Heart Clinic were approached for study participation. Those agreeable underwent a full clinical assessment, cardiopulmonary stress testing, transthoracic echocardiogram and dual energy cardiac CT. Twenty-three patients were included in the study (30±10 years, 26% women). Three (13%) patients had evidence of silent thrombi detected on CT. All 3 of these patients had an extra-cardiac conduit and mural thrombus was found within the conduit. Older age at the time of the Fontan operation was associated with the presence of thrombus (21±14 vs. 11±6 years, P = 0.05). Although the 3 thrombotic events occurred among those with an extra-cardiac conduit, there was no statistical difference in the location of thrombus based on the type of Fontan modification. Thirteen percent of adult patients post Fontan procedure have clinically silent thrombi. Given the significant risk of thromboembolic complications, large randomized prospective studies looking at anticoagulation therapy in all Fontan patients are urgently needed. In the meanwhile, given the important rate of silent thrombi, a systematic robust screening protocol that includes noninvasive low radiation methods such as dual energy cardiac CT methods should be considered.