Introduction
Kawasaki disease is an acute vasculitis that primarily affects children and carries a risk of coronary artery aneurysms Reference Kawasaki, Kosaki, Okawa, Shigematsu and Yanagawa1 and other cardiac complications involving the pericardium, myocardium, endocardium, and valves. Reference Newburger, Takahashi and Gerber2 Histopathological studies have shown that myocarditis in the acute phase of Kawasaki disease is characterised by inflammatory cell infiltration and myocardial interstitial oedema. Reference Harada, Yokouchi and Oharaseki3
Although PR interval prolongation is a common electrocardiographic finding during the acute phase of Kawasaki disease, complete atrioventricular block is an extremely rare complication in Kawasaki disease. Reference Liu, Wang, Wu, Liu and Hu4 The mechanism may be related to inflammatory processes or microcirculatory disturbances in the cardiac conduction system. Reference Sumitomo, Karasawa and Taniguchi5 In most reported cases, atrioventricular block in Kawasaki disease is transient, particularly when not associated with coronary artery lesions. However, persistent complete atrioventricular block, especially in infants without prior cardiac abnormalities, is exceptionally rare and not well understood.
This case report describes a rare instance of persistent complete atrioventricular block following Kawasaki disease in an 11-month-old boy. It aims to contribute to the limited understanding of severe conduction disturbances in Kawasaki disease, particularly in infants, and underscores the importance of vigilant cardiac monitoring, even in the absence of coronary artery lesions.
Case
An 11-month-old boy was referred to our hospital due to fever for 2 days. On admission, the patient exhibited eyes and lip injection, skin rash including at the site of a Bacille de Calmette et Guérin vaccination, cervical lymphadenopathy, and oedematous fingers, which satisfied the diagnostic criteria of Kawasaki disease. Reference Kobayashi, Ayusawa and Suzuki6 His body temperature was 37.9°C, systolic blood pressure was 105 mmHg, and heart rate was regular at 130 beats per minute. Initial laboratory data showed a white blood cell count of 13,000 /μL, a platelet count of 404,000 /μL, C-reactive protein of 0.12 mg/dL, serum albumin of 4.7 g/dL, serum natrium of 139 mmol/L, plasma brain natriuretic peptide of 79.5 pg/mL, creatine kinase of 144 U/L, and high-sensitivity troponin I below the detection limit. Blood coagulation was normal except for a mild elevation in D-dimer (1.7 μg/mL). Chest X-ray (Figure 1a) showed a cardiothoracic ratio of 0.55. Echocardiography demonstrated moderate mitral regurgitation (Figure 1b), and the absence of coronary arterial dilatation (Figure 1c) or congenital heart defects. Thereby, intravenous immunoglobulin of 2 g/kg was administrated under electrocardiography monitoring.
Imaging examinations of the patient at the time of the visit. ( a ) Chest X-ray. The cardiothoracic ratio is 0.55. ( b ) Echocardiography. Moderate mitral regurgitation is observed. (c) Echocardiography. Measurements of the coronary artery bases show normal dimensions: 1.9 mm for the left (upper) and 1.7 mm for the right (lower). Abbreviations: LV, left ventricle; LA, left atrium; MR, mitral regurgitation; LCA, left coronary artery; RCA, right coronary artery.
A few hours after admission, his heart rate suddenly decreased from 130 beats per minute to 46 beats per minute (Figure 2a). Subsequently, the 12-lead electrocardiography showed complete atrioventricular block with a P rate of 130 beats per minute and a QRS rate of 56 beats per minute, and positive T waves atypical for the patient’s age were noted in leads V2 to V4 (Figure 2b). The patient was subsequently transferred to a tertiary care centre for advanced management.
Electrocardiograms of the patient. ( a ) Monitor electrocardiogram during sleep. This shows an advanced atrioventricular block with ventricular escape rhythms (arrows). The heart rate is 46 beats per minute. ( b ) The 12-lead electrocardiogram just before transportation. This shows a complete atrioventricular block with a heart rate of 56 beats per minute. Positive T waves atypical for the patient’s age were noted in leads V2 to V4; however, no definitive evidence of myocardial ischaemia was identified.
His past records were reviewed in detail, no bradycardia was noted at the referring hospital, and his heart rate was recorded as 110 beats per minute at another hospital the day prior to referral. He had no significant medical or family history of heart disease or arrhythmia, and it turned out that his perinatal records indicated a normal fetal heart rate (ranging between 110 and 140 beats per minute), and his past infant health check-ups showed no abnormalities. In addition, his SARS-CoV-2 antigen, antinuclear and antistreptolysin O antibodies were negative, respectively, and his maternal anti-SS-A antibody was also negative.
After transfer to a tertiary care centre, despite resolution of fever after intravenous immunoglobulin therapy, electrocardiography showed persistent complete atrioventricular block and no ischaemic findings, including ST-T changes. Holter electrocardiography showed a total of 82,993 beats per day, with maximum, minimum, and average heart rates of 87, 45, and 58 beats per minute, respectively. Chest X-ray showed a cardiothoracic ratio of 0.50. Plasma brain natriuretic peptide was 275.6 pg/mL. Echocardiography revealed no coronary artery lesions, trivial mitral regurgitation, a Z-score of 2.12 for the left ventricular end-diastolic diameter, and a left ventricular ejection fraction of 67.0%. CT angiography was not performed because the echocardiogram and blood tests showed no signs of coronary artery lesions. Whereas he had no symptoms associated with complete atrioventricular block, so we deferred pacemaker implantation and closely observed his clinical manifestations at the outpatient clinic. At the last follow-up at the age of 24 months, he had no symptoms, although complete atrioventricular block was persistent. The T waves at V2 and V3 on the 12-lead electrocardiogram became negative and flat, respectively, which is an age-appropriate finding. Chest X-ray showed a cardiothoracic ratio of 0.60. Plasma brain natriuretic peptide was 104.32 pg/mL. Echocardiography revealed a Z-score of 2.17 for the left ventricular end-diastolic diameter and a left ventricular ejection fraction of 70.8%, respectively. Due to concerns about potential lead complications during growth, a pacemaker was not implanted, and the patient is being closely monitored.
Discussion
To our knowledge, this is the first case of an infant with Kawasaki disease following persistent complete atrioventricular block in spite of appropriate treatment during the acute phase. Usually, the pathogenesis of complete atrioventricular block among the young is variable, including surgery or catheterisation-induced trauma, coronary artery disease, acute or chronic infectious processes, myocarditis, hypersensitivity cardiomyopathy, metabolic abnormalities, hypothyroidism, infiltrative processes, or through a pathological neurocardiogenic mechanism. Reference Barra, Providência, Paiva, Nascimento and Marques7 Sumitomo, et al. reported latent abnormal atrioventricular conduction function in patients with a history of Kawasaki disease. Reference Sumitomo, Karasawa and Taniguchi5 They suggested that abnormal atrioventricular conduction might possibly be caused by myocarditis or abnormal microcirculation in the atrioventricular node artery. As so far, there were two case reports of complete atrioventricular block associated with Kawasaki disease; one was owing to coronary arterial lesions following myocardial ischaemia Reference Fujiwara, Kawai and Hamashima8 , which probably involved the atrioventricular node artery, whereas the other was transient complete atrioventricular block during the acute phase of Kawasaki disease. Reference Liu, Wang, Wu, Liu and Hu4 The latter is resembled for our present case because myocarditis associated Kawasaki disease directly influences the conduction system. The present clinical finding that complete atrioventricular block persisted even in the late stage of Kawasaki disease seemed to be extremely rare, but the underlying mechanism may align with those previously discussed in the literature. Although transient bradycardia has been reported in the past with intravenous immunoglobulin therapy, in this case, it was permanent and unlikely to be related.
Pacemaker implantation in paediatric patients requires careful consideration. In this case, despite bradycardia, the patient’s general condition remained stable, with an average heart rate of 58 beats per minute recorded on Holter electrocardiography. In addition, there was no increase in brain natriuretic peptide levels, no increase in the cardiothoracic ratio, and no cardiac hypertrophy on echocardiography even in the outpatient period. Given these points, close monitoring without immediate pacemaker implantation was chosen. According to the guideline for device implantation in arrhythmias, it is not recommended in asymptomatic patients with complete atrioventricular block and absence of cardiac dysfunction. Reference Epstein, DiMarco, Ellenbogen and etal9 The patient’s good growth and development at 24 months of age suggest that this conservative approach was appropriate. However, careful follow-up will be necessary to evaluate the conduction system abnormality.
This case suggests that Kawasaki disease may cause complete atrioventricular block through mechanisms unrelated to coronary artery lesions. Although the complete atrioventricular block was permanent, it was not fatal during the acute phase, allowing pacemaker insertion to be avoided. It underscores the importance of careful cardiac monitoring during the acute phase of Kawasaki disease and reinforces the need to consider cardiac complications even in the absence of coronary artery lesions.
In this case, we were unable to obtain an electrocardiogram before he developed complete atrioventricular block. In addition, we did not measure antibody titres for various viruses or analyse blood cytokines. Consequently, it remains difficult to rule out the possibility that a rare viral myocarditis, presenting with Kawasaki disease-like symptoms, may have caused the complete atrioventricular block. To better understand the relationship between Kawasaki disease and complete atrioventricular block, as well as to elucidate the mechanisms underlying permanent cardiac conduction disturbances, further similar cases need to be examined.
Acknowledgements
The authors would like to thank the medical staff of the Aichi Children’s Health and Medical Center and TOYOTA Memorial Hospital who contributed to the care of the patient. The authors thank FORTE Science Communications (https://www.forte-science.co.jp/) for English language editing.
Financial support
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Competing interests
The authors declare no conflict of interest.
Ethical standards
The authors assert that all work reported complies with the ethical standards of the Declaration of Helsinki and institutional and national research committees.
