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Thromboembolism in Adult Fontan Patients
Study Questions:
What are the risks of thrombotic and embolic complications and impact of anticoagulation after the Fontan operation?
Methods:
A retrospective review was performed at a single center of patients with atrial arrhythmia after Fontan operation evaluated between 1994 and 2014. Thrombotic and embolic complications were classified as either systemic or nonsystemic. Patients were also categorized as those receiving full anticoagulation, antiplatelet agents, or no therapy.
Results:
A total of 278 patients, mean age 31 ± 9 years, were followed for 88 ± 14 months. Of these, 181 patients were in the antiplatelet group, 91 patients were in the anticoagulation group, and 6 received no anticoagulation. There were 97 thrombotic and embolic complications in 81 (29%) patients, of which 32 were systemic (event rate of 2.1 per 100 patient-years), and 65 were nonsystemic (event rate of 4.4 per 100 patient-years). Prevalence of thrombotic and embolic complication was 18% at 5 years and 55% at 10 years. Atriopulmonary connection was a risk factor for thrombotic and embolic complication (hazard ratio, 2.31; 95% confidence interval, 161-4.64). Anticoagulation was protective against thrombotic and embolic complication and resulted in a reduction of risk of 2.5 thrombotic and embolic complications per 100 patient-years. Anticoagulation was associated with a lower risk of death and hospitalization (p = 0.02). Bleeding complications occurred in 7% of patients and were similar in all groups.
Conclusions:
Anticoagulation was associated with a lower thromboembolic complication rate and lower risk of death and hospitalization, without a significant increase in bleeding risk.
Perspective:
The optimal anticoagulation strategy for patients following the Fontan procedure remains controversial. A randomized trial comparing aspirin to warfarin in pediatric patients reported no difference in outcome. The current trial showed a relatively high rate of thromboembolic complication in Fontan patients, likely due to the older age of patients, high number patients with atriopulmonary Fontan connections, and necessity of atrial tachyarrhythmia occurrence for enrollment. Additionally, approximately one-third of patients were found to have subtherapeutic international normalized ratio in this study, which may have contributed to the rate of thromboembolic complications. This study reinforces current guidelines recommending anticoagulation for patients with complex congenital heart disease and recurrent or sustained tachyarrhythmias. The study also supports consideration of empiric anticoagulation for older patients with atriopulmonary Fontan connections. Nonvitamin K oral anticoagulants may prove to have an important role in the population, although further study is required to confirm safety and efficacy.
Keywords: Anticoagulants, Arrhythmias, Cardiac, Aspirin, Embolism, Fontan Procedure, Heart Conduction System, Heart Defects, Congenital, Hemorrhage, Platelet Aggregation Inhibitors, Risk Factors, Secondary Prevention, Tachycardia, Thrombosis, Warfarin
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