Low Molecular Weight Heparin vs. Warfarin for Thromboprophylaxis in Children with Coronary Artery Aneurysms After Kawasaki Disease: A Pragmatic Registry Trial

Abstract Background The substantial risk of thrombosis in large coronary artery aneurysms (CAA) (maximum z-score ever recorded ≥10) after Kawasaki disease (KD) mandates effective thromboprophylaxis. We sought to determine the effectiveness of anticoagulation (low molecular weight heparin (LMWH) or warfarin) for thromboprophylaxis in large CAA. Methods Data were used from 383 patients enrolled in the International KD Registry (IKDR). Time-to-event analysis was used to account for differences in treatment duration and follow-up. Results From diagnosis onward (96% received acetylsalicylic acid concomitantly), 114 patients received LMWH (median duration: 6.2 (IQR:2.5-12.7) months), 80 warfarin (median duration 2.2 (IQR:0.9-7.1) years) and 189 no anticoagulation. Cumulative incidence of coronary artery thrombosis with LMWH was 5.7±3.0%, warfarin 6.7±3.7% and with no anticoagulation 20.6±3.0% (p Conclusions LMWH and warfarin appear to have equivalent effectiveness for preventing thrombosis in large CAAs after KD, although event rate for secondary thromboprophylaxis and safety outcomes were low. Based on our findings, all patients with CAA z-score ≥10 should receive anticoagulation but the choice of agent might be informed by secondary risk factors and patient preferences.