Abstract 17328: Novel Oral Anticoagulants in Adult Fontan Patients: A Multi-Site Experience

Introduction: Adult Fontan patients are typically prescribed antiplatelet or anticoagulant therapy to manage increased risk for thrombotic and embolic complications (TECs). There is a Class III recommendation against the use of novel oral anticoagulants (NOACs) in this population due to a paucity of data. We hypothesized that NOACs are potentially non-inferior to warfarin in adult Fontan patients. Methods: We performed a multi-site retrospective review of adult Fontan patients, evaluated at three major academic medical centers (1995-2018), prescribed NOAC, warfarin, or aspirin therapy. Results: We identified 267 adult Fontan patients: 48 on NOACs, 107 on warfarin, and 180 on aspirin (14.4% to 54.2% cross-over amongst groups). Patients were more likely to have clinically significant bleeds (“bleeds”) if on a NOAC (HR=9.3, CI=3.0-28.4) or warfarin (HR=4.1, CI=1.6-10.5) versus aspirin. Bleed hazard ratio differences between NOAC and warfarin patients were not statistically significant (HR=2.3, CI=0.9-5.9). Patients on NOACs were not more likely to suffer TECs than patients on warfarin (HR=1.7, CI=0.4-6.3) or aspirin (HR=2.8, CI=0.7-10.3). Aspirin patients were younger, healthier, and had more favorable Fontan palliation. The traditional scoring systems to predict bleeds (HAS-BLED) and TECs (CHA 2 DS 2 VASc) were not predictive in this patient population. The only risk factor we identified for bleeds was a history of/predisposition to bleeding (OR=10.2, CI=4.4-23.6). Risk factors we identified for TECs included diabetes mellitus (OR=5.0, CI=2.2-11.4), labile international normalized ratio (OR=3.7, CI=1.1-12.4), and CHF (only in the NOAC/warfarin subgroup, OR=4.4, CI=1.2-16.3). Conclusions: NOACs are a potentially noninferior alternative to warfarin for adult Fontan patients. Our findings have laid the groundwork for a randomized control trial comparing the use of NOACs to warfarin in adult Fontan patients to test noninferiority or equivalence.