Background
Kawasaki disease is a systemic vasculitis that predominantly affects children and can lead to coronary artery aneurysm formation. Although most patients recover without sequelae, those with persistent coronary aneurysms require lifelong antithrombotic therapy and follow-up. Transitioning care from paediatric to adult cardiology is a crucial step for such patients, as poor adherence and inadequate patient education may lead to catastrophic thrombotic events. The American Heart Association has emphasised the importance of structured transition programmes based on the Six Core Elements of Health Care Transition, Reference Chahal1 which include readiness assessment, care planning, and post-transfer follow-up.
Here, we present a case of acute myocardial infarction due to temporary interruption of antithrombotic therapy in a young adult with Kawasaki disease, in the context of transition to adult care.
Case presentation
A 20-year-old male presented to the emergency department with acute-onset chest pain. He had been diagnosed with Kawasaki disease at the age of six and was treated with intravenous immunoglobulin and high-dose aspirin during the acute phase. Coronary angiography at that time revealed coronary aneurysms, and long-term antithrombotic therapy was initiated.
During childhood, he was followed at the Children’s Medical Center, where he received aspirin 100 mg/day and warfarin 4 mg/day. Although the target INR during paediatric follow-up had been relatively low (approximately 1.46), he had been maintained on combined antiplatelet and anticoagulant therapy because of coronary aneurysm-related thrombotic risk.
At age 19, as the paediatric centre limited follow-up to patients under 18 years, his care was transferred to a local adult cardiology clinic. Adult follow-up was successfully established, and the same medications were continued. Approximately one year after transfer, although medications had been prescribed until the next visit, he discontinued both aspirin and warfarin for one week due to a busy schedule.
He had no history of smoking, no family history of premature coronary artery disease, and no other comorbid conditions aside from Kawasaki disease.
On arrival, blood pressure was 116/67 mmHg, and heart rate was 84 beats per minute, indicating haemodynamic stability, although persistent chest pain was present. The electrocardiogram showed anterior ST-segment elevation, and cardiac enzymes were markedly elevated (Figure 1A). Serum creatine kinase was 456 U/L, and cardiac troponin I was 0.76 ng/mL on admission. Transthoracic echocardiography demonstrated hypokinesis of the anteroseptal to anterior wall. At the time of presentation, the INR was 0.95, reflecting recent discontinuation of warfarin.
Coronary angiography and electrocardiographic findings in a 20-year-old man with Kawasaki disease-related coronary aneurysm. ( 1A ) Electrocardiogram obtained before treatment, showing ST-segment elevation in leads I, aVL, and V2–V4. ( 1B ) Pre-procedural left coronary angiogram in the RAO-caudal projection showing total occlusion of the proximal left anterior descending artery (LAD #6) with a large thrombus burden within an aneurysmal segment (white arrow). ( 1C ) Follow-up coronary angiogram in the RAO-caudal projection obtained at the time of intra-aortic balloon pumping (IABP) removal, demonstrating improved coronary flow within the aneurysmal LAD segment without stent placement (white arrow). ( 1D ) Electrocardiogram obtained at the time of IABP removal, showing resolution of ST-segment elevation and T-wave inversion in leads V2–V5.
Figure 1. Long description
Panel A: Electrocardiogram showing ST-segment elevation in leads I, aVL, and V2 to V4. Panel B: Pre-procedural left coronary angiogram in the RAO-caudal projection showing total occlusion of the proximal left anterior descending artery with a large thrombus burden within an aneurysmal segment. Panel C: Follow-up coronary angiogram in the RAO-caudal projection demonstrating improved coronary flow within the aneurysmal LAD segment without stent placement. Panel D: Electrocardiogram showing resolution of ST-segment elevation and T-wave inversion in leads V2 to V5.
Coronary angiography demonstrated total occlusion of the proximal left anterior descending artery (LAD #6) with multiple thrombi in a dilated segment corresponding to a residual aneurysm (Figure 1B). Intravascular ultrasound revealed a large aneurysmal segment with a maximal diameter of 7.9 mm and substantial residual thrombus burden.
The patient underwent guidewire crossing, thrombus aspiration, and plain balloon angioplasty, achieving TIMI 2 flow without stent placement. Stent implantation was avoided because of the large aneurysmal vessel diameter and the presence of extensive thrombus, raising concerns regarding stent malapposition and recurrent thrombosis. The initial strategy prioritised restoration of coronary flow, with the expectation that intensified antithrombotic therapy would further improve coronary perfusion.
Because coronary flow remained suboptimal after the initial procedure, intra-aortic balloon pumping, and intensive antithrombotic therapy were continued. Follow-up coronary angiography performed at the time of intra-aortic balloon pumping removal demonstrated improved coronary flow within the aneurysmal LAD segment without stent implantation (Figure 1C). Electrocardiography obtained at the same time showed resolution of ST-segment elevation with T-wave inversion in leads V2–V5 (Figure 1D). Following haemodynamic stabilization, dual antithrombotic therapy was reintroduced with aspirin 100 mg/day and warfarin 4 mg/day. The patient was subsequently managed with a target INR of 2.5–3.0, which has been maintained during follow-up.
At three-month follow-up, he remained asymptomatic, reported good adherence to medication. Functional status during exercise was normal. Planned follow-up includes myocardial perfusion scintigraphy to evaluate LAD perfusion.
Discussion
This case illustrates the risk of acute coronary thrombosis associated with even brief interruption of antithrombotic therapy in patients with Kawasaki disease-related coronary aneurysms.
Importantly, although the patient had been formally transferred to and followed in an adult cardiology clinic, the immediate trigger of myocardial infarction was one week of self-discontinuation of medication. Therefore, this case should not be interpreted as a failure of transfer logistics. Rather, this case highlights the need to distinguish between successful transfer of care, adequacy of transition-related self-management preparation, and simple medication nonadherence. In this patient, formal follow-up had been established; however, understanding of the lifelong necessity of antithrombotic therapy may have been insufficient, suggesting a potential gap in self-management education during the transition process.
Previous reports have documented similar thrombotic complications among young adults with incomplete transition support. Reference Chahal1 The Six Core Elements of Health Care Transition provide a structured framework to prevent such outcomes, emphasising readiness evaluation, individualised care planning, and continuity monitoring after transfer. Reference Lloyd-Jones2 In this patient, although medical follow-up was technically maintained, the educational and behavioural aspects of self-management were insufficiently addressed—a gap commonly observed during the transition period. From a pathophysiological standpoint, aneurysmal segments with altered flow dynamics and endothelial dysfunction remain highly thrombogenic, even in young adults. Therefore, strict adherence to anticoagulant and antiplatelet therapy is indispensable.
This case suggests that effective transition may require not only successful transfer of care but also reinforcement of self-management skills and medication adherence. However, given that this is a single case, no definitive conclusions regarding transition systems can be drawn.
Limitations
This case is limited by lack of detailed historical coronary data, short follow-up, and inability to infer causality from a single case.
Conclusion
This case highlights the potential danger of brief interruption of antithrombotic therapy in Kawasaki disease-related coronary aneurysm and suggests the importance of reinforcing medication adherence and self-management during the transition to adult care.
Acknowledgements
The authors thank Dr Masaki Monden, Dr Yuro Matsunaga, and Dr Toshiki Setoguchi for contributing to the treatment.
Author contribution
H.K.: data curation, drafting the manuscript.
D.F.: overall case management, patient consent, manuscript supervision.
H.F., N.M., and Y.O.: revision and clinical advice.
Financial support
None.
Competing interests
We have no potential conflicts of interest related to this manuscript.
