Patients born with certain congenital heart defects, that essentially only have one functioning heart ventricle, have undergone the Fontan surgery in order to alleviate their symptoms. One of the risks associated with Fontan procedures includes the risk of thromboembolic events. In order to minimize this risk Fontan patients are managed with anticoagulant medications, such as warfarin. Therefore, there is no data available regarding the Fontan population. Recent Novel Oral Anticoagulants (NOACs) have been shown to be just as effective in the general population, when compared to traditional anticoagulant medications. Unfortunately, these studies have not included patients with Fontan physiology.
This project involved a retrospective analysis on the adult Fontan population at Ahmanson/UCLA Adult Congenital Heart Disease Center who need anticoagulants. Patients from the adult Fontan population who have been followed long term and had clinical data on file were included in the study (n=238). The total adult Fontan population was further narrowed to compare patients who were taking either NOACs or warfarin/warfarin+aspirin. Patients who were on an aspirin only anticoagulation therapy, or were not on an anticoagulation therapy at all, were excluded from this analysis.
Out of the total Fontan population (n=238), the data was categorized into groups who were taking either NOACs (n=11) or warfarin/warfarin+aspirin (n=60). The remaining portion of patients, which were taking aspirin only or were not taking any anticoagulation medication, were excluded (n=98). The NOAC subgroup and warfarin subgroup had similar baseline creatinine values, hemoglobin values, oxygen saturation levels, and average number of patients on anti-arrhythmic medication. The warfarin subgroup had a lower amount of cardiac interventions via catheter (0.5) compared to the NOAC subgroup (1.8). The number of patients with a normal baseline cardiac function, ventricular ejection fraction of 50-70%, was 82% in the NOAC subgroup compared to 54% in the warfarin subgroup (P = 0.08). No NOAC related hospitalizations, bleeding requiring transfusion, or adverse side effects were noted in the NOAC group.
There are some differences between the two anticoagulant therapy groups. Overall, the NOAC subgroup appears to have similar outcomes compared to the warfarin subgroup in the Fontan population. Unfortunately, the NOAC subgroup (n=11) was relatively small. It is important to keep in mind that the Fontan population makes up a small fraction of the total number of patients with congenital heart defects. Furthermore, the number of Fontan patients who are on a NOAC therapy is even smaller. Rivaroxaban and Apixaban, NOACs approved for use in 2011 and 2014 respectively, are quite new compared to warfarin, which was approved for use in 1954. This NOAC Fontan subpopulation will hopefully grow in the future and provide more data. This could be a great impact in anticoagulant therapies, as it would provide more treatment options for this clinically challenging patient population.