Bleeding risk associated with combination thromboprophylaxis therapy is low for patients with coronary artery aneurysms after Kawasaki disease.

Background: Kawasaki disease (KD) may lead to coronary artery aneurysms (CAA) with potential for thrombosis. We aimed to determine the bleeding risk during thromboprophylaxis regimens with dual and triple therapy.

Methods: KD patients with medium to large CAAs receiving combination thromboprophylaxis therapy (dual or triple therapy with acetylsalicylic acid (ASA), clopidogrel, low molecular weight heparin (LMWH) or warfarin) were reviewed (1979-2017). Treatment periods <30 days were excluded. Bleeding events were classified using the Bleeding Academic Research Consortium (BARC) Score. The incidence of bleeding events per patient year of exposure was determined for each regimen.

Results: n = 98 of 3022 KD (23 females:75 males) were included. Median age at diagnosis was 2.6 years (IQR: 0.6-6.2), median maximum CAA z-score was 18.0 (range: 5-65.5, IQR: 10.8-28.0, m = 6) and median follow-up duration was 6.5 years (IQR: 2.5-20.2). The incidence of type ≥2 bleeds per patient-year for each regimen was 0 (ASA + clopidogrel+LMWH), 0.03 (ASA + clopidogrel), 0.06 (ASA + warfarin), 0.06 (ASA + clopidogrel+warfarin), and 0.1 (ASA + LMWH) in ascending order. 31 bleeding events requiring medical attention (type ≥2) occurred in 30 patients (median age 7.8 years). Of the 17 type ≥2 bleeds on warfarin with an International Normalised Ratio (INR) available, 13 occurred with an INR >3. For patients receiving triple therapy (dual antiplatelet with anticoagulant), there were 57 bleeding events over 20 treatment periods.

Conclusions: The overall bleeding risk was low in KD patients receiving combination thromboprophylaxis, and not significantly different across all regimens. Type ≥2 bleeding events that occurred on warfarin were most frequently associated with high INR values.