Myocardial Infarction in Kawasaki Disease: Diagnosis and Outcome

Source: Ghelani SJ, Baker AL, Friedman K, et al. Myocardial infarction in Kawasaki disease. J Pediatr. 2025;284:114638; doi: 10.1016/j.jpeds.2025.114638.Investigators from Boston Children’s Hospital conducted a retrospective study to describe the clinical features, treatments and outcomes in children with myocardial infarction (MI) occurring as a result of Kawasaki disease (KD). All patients treated at their institution with KD and MI between 1984 and 2023 were included in the study. Demographic and clinical data were collected by review of medical records and available databases. The diagnosis of acute MI was based on symptoms, changes in cardiac enzymes, or electrocardiographic (ECG) or imaging findings. The number of doses of intravenous immunoglobulin (IVIG) administered to study patients and use of corticosteroid therapy were recorded. Information on maximum coronary artery dimensions was extracted from medical records, and the classification of coronary artery aneurysms was based on dimensions and Z-scores using specific thresholds. The use of antithrombotic and thrombolytic therapies in study children also was recorded. Outcomes included death, decreased cardiac function, interventions such as coronary artery bypass grafting (CABG), and listing for heart transplantation.During the 39-year study period, 22 children with KD had a diagnosis of MI. The median age at onset of KD in these patients was 14 months (range, 3 months to 15 years), and 86% were male. Of the 22 study children, 20 (91%) received IVIG a median of 10 days after the onset of KD, with 10 (45%) receiving 2 doses and 3 receiving ≥3 doses. Corticosteroids were administered to 7 (32%) children. MI occurred within 3 months of the onset of KD in 48% of study participants and within 1 year in 62%. All of the children with MI had at least 1 large coronary artery aneurysm. In 7 (32%) patients, the MI was diagnosed by the presence of symptoms including chest pain, fatigue, syncope, left ear pain misdiag-nosed as otitis media, upper extremity pain, and vomiting. Findings consistent with MI were seen on MRI and/or echocardiogram in more than 50% of children. The diagnosis of MI was missed in 7 patients for whom MI was an incidental finding on MRIs. At the time of diagnosis, 10 (56%) children with MI were being treated with anticoagulation therapy, although treatment was not always optimal. Overall, 2 children with MI and KD died, both in 1988. Of the 20 surviving patients, 5 had decreased left ventricular function on their most recent ECG. Seven children underwent a CABG procedure, including 1 who died in the operating room. One patient is currently listed for heart transplantation.The authors conclude that the diagnosis of MI in children with KD initially was missed frequently because of lack of specific symptoms.Dr Philip has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.KD is the most common cause of acquired cardiac disease in children in developed countries. (See AAP GrandRounds. 2025;534:43.)1 It primarily affects children under 5 and can cause coronary artery dilation/aneurysms in up to 25% of untreated patients.2 The risk of MI is highest in the first 2–3 months and occurs exclusively in those with giant aneurysms (GA).3 The risk persists lifelong, necessitating ongoing surveillance.4The current single-center retrospective study describes the long-term follow-up and management of 22 patients with KD complicated by GA and MI over 39 years. Findings confirm that MI in KD is confined to patients with GA but highlights the high rate of missed diagnoses, likely due to atypical non-specific symptoms and the young age complicating history-taking. Only 32% experienced symptoms; 87% of those diagnosed with MI by cardiac MRI (CMR) were incidental findings. This underscores the need for clinicians to maintain a high index of suspicion, especially given the updated 2024 KD guidelines emphasizing vague signs like poorly localized pain, unexplained crying, restlessness, unusual pallor, or sweating as harbingers for cardiac events in KD with GA.5 Despite sedation challenges in young children, the high incidental detection rate with CMR underscores its importance as a screening tool.There was considerable variability in anti-thrombotic therapy within the cohort. Nearly half experienced poor outcomes (10% mortality, 10% transplant, and 23% depressed left ventricular systolic dysfunction). This emphasizes the importance of intensification of primary therapy, diligent surveillance, and adherence to management guidelines. In older patients, the potential role of calcium scores, not currently in guidelines, warrants consideration.The study’s main limitation is its retrospective nature over 4 decades, with data loss due to evolving diagnostic and treatment paradigms. Notably, all mortality occurred in the 1980s, reflecting changing practices.Patients with KD with GA are at high risk and require a high index of suspicion and meticulous surveillance to detect MI, often with atypical or absent symptoms.