A Multicenter, Randomized Trial Comparing Heparin/Warfarin and Acetylsalicylic Acid as Primary Thromboprophylaxis for 2 years After the Fontan Procedure in Children

Study Questions:

What is the safety and efficacy of acetylsalicylic acid (ASA) as compared with warfarin for thromboprophylaxis after the Fontan procedure?

Methods:

A multicenter, randomized study was performed. At the time of the Fontan procedure, patients were randomized to 2 years of ASA at a dose of 5 mg/kg/day or warfarin with a goal international normalized ratio (INR) of 2.0-3.0. Patients in the warfarin group received 24 hours of heparin prior to initiation of warfarin. Patients underwent transthoracic and transesophageal echocardiograms 3 months and 2 years after the Fontan procedure. The primary endpoint for the study was intracardiac or embolic thrombosis.

Results:

Of 111 patients randomized, 57 received ASA and 54 received warfarin. A majority of patients in both groups (86% in the ASA group and 85% in the warfarin group) underwent extracardiac Fontans, most of which were fenestrated. There were 13 thromboses (3 clinical, 10 routine echo) in the heparin/warfarin group and 12 thromboses (4 clinical, 9 routine echo) in the ASA group. Major bleeding occurred in one patient in each group.

Conclusions:

There is no significant difference between ASA and warfarin as primary thromboprophylaxis for the first 2 years after Fontan surgery.

Perspective:

This important and well-designed study demonstrated no benefit in warfarin over ASA for patients in the first 2 years after a Fontan procedure. There is significant practice pattern variation between centers in post-Fontan anticoagulation, with little data to support any particular approach. Interestingly, the vast majority (approximately 85%) of patients in the study had undergone extracardiac conduit Fontans. The high overall thrombus prevalence of 19% suggests that alternative anticoagulation approaches should be considered. This study also points to the challenges of warfarin anticoagulation in children. Although the mean INR at time of thrombus detection was 2.2, 41% of all INR measurements were below the therapeutic range.

Clinical Topics: Anticoagulation Management, Cardiac Surgery, Congenital Heart Disease and Pediatric Cardiology, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Cardiac Surgery and CHD & Pediatrics, Congenital Heart Disease, CHD & Pediatrics and Imaging, CHD & Pediatrics and Interventions, CHD & Pediatrics and Prevention, Interventions and Imaging, Echocardiography/Ultrasound

Keywords: Child, Heart Diseases, Blood Coagulation, Fontan Procedure, Thrombosis, Warfarin, Heparin, Hemorrhage, Echocardiography, Transesophageal


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