Incomplete Kawasaki disease with multivessel giant coronary aneurysms and refractory thrombosis in an infant; a case report.

Background: Kawasaki disease (KD) is an acute vasculitis of childhood with risk of coronary artery aneurysm (CAA) formation. Giant CAAs, thrombosis, and the need for revascularization in infancy are uncommon and clinically challenging. Case summary: A 9-month-old infant presented with persistent fever for 3 weeks before diagnosis and incomplete KD features. Echocardiography and computed tomographic coronary angiography revealed multivessel giant CAAs involving the left anterior descending (LAD), right coronary artery, and left circumflex (LCX) arteries, with multiple thrombi and a left atrial appendage thrombus. Alteplase was given in the intensive care unit for three cycles without thrombus resolution. A catheter-based attempt to recanalize the occluded LCX was unsuccessful. The patient was discharged on triple therapy with aspirin, clopidogrel, and rivaroxaban. Discussion: This case highlights the consequences of delayed recognition of incomplete KD, the limited efficacy of thrombolysis with alteplase in coronary thrombosis secondary to KD, the technical limitations and uncertain durability of percutaneous coronary intervention (PCI) in KD-related lesions during infancy, and evolving antithrombotic strategies, including the emerging role of direct oral anticoagulants for giant CAAs. Conclusion: Earlier diagnosis and risk-stratified therapy are essential to mitigate CAA complications. When revascularization and thrombolysis are not feasible or unsuccessful, individualized combinations of double antiplatelet and anticoagulant therapy may reduce thrombotic risk, necessitating close multidisciplinary follow-up.