A 14-Year-Old Boy With Unexplained, Recurring Fever

Shah Azmoon, MD; Matthew Budoff, MD; David Atkinson, MD

Disclosures

June 17, 2019

ECG findings in KD may reveal low-voltage R waves and flattening T waves, with possible prolongation of the PR and QT intervals. Although not common, findings indicative of an acute myocardial infarction (MI) may be seen, including Q waves and repolarization abnormalities.[11,12,13] Early echocardiography may help suggest the diagnosis of KD when suspected in patients with nontypical presentations. The associated myocardial inflammation may reveal mild left ventricular dilation along with a decrease in systolic function, mitral regurgitation, pericardial effusion, aortic root dilation, and mild aortic insufficiency.[14,15] These echocardiographic findings tend to spontaneously improve within a few weeks of therapy, although abnormalities may persist several months to years after the diagnosis.

In about 50% of children with KD, coronary artery dilation may be seen by the 10th day of the disease process. Male infants have the highest risk for coronary artery aneurysms.[16] Enlargement of the left main coronary artery is usually seen, with ectasia of the left anterior descending and/or circumflex coronary arteries.[4] Aneurysm forms as a result of arterial vessel-wall destruction during the accumulation of cytokines and chemokines in an proinflammatory milieu.[17] An increased risk for thrombosis is noted during the acute phase of the illness, caused by enhanced platelet activity and stasis within the aneurysm. Stenosis can occur at the proximal and distal ends of an aneurysm.

Aneurysms that are > 15 mm in length and > 5 mm in diameter are at risk for local vessel stenosis within a remodeled aneurysm.[18] Long-term anticoagulation with antiplatelet agents, such as aspirin and concomitant warfarin (international normalized ratio, 2-2.5), has been used to reduce the risk for vessel occlusion in patients with large (> 6 mm) or giant (> 8 mm) aneurysms.[19] Fortunately, approximately 50% of coronary artery aneurysms tend to regress within the first 2 years via proliferation of intimal cells, but these patients are still at increased risk for accelerated atherosclerosis and are considered at moderate risk for future ischemic disease.[20,21,22] Regression is more common in smaller aneurysms (< 8 mm), younger patients, and fusiform aneurysms (versus saccular).[20,23,24]

In patients with KD in whom prompt therapy is initiated with aspirin and gamma-globulin, the prevalence of coronary artery aneurysm is reduced to < 5%.[17,19] Therapy with aspirin has been instrumental in suppression of the anti-inflammatory process, leading to a significant decrease in mortality from 2% to 0.5%.[4] In general, antiplatelet therapy should be continued until documented regression of the coronary aneurysm, with avoidance of high-risk sports activities to minimize the risk for bleeding.[25] The recommended initial dose of aspirin for effective anti-inflammatory action is 80-100 mg/kg, divided into 4 daily doses.[23] Subsequent lower doses of aspirin for effective antiplatelet action may be used.

Gamma-globulins also appear to have anti-inflammatory effects, and multiple studies have validated a decrease in the frequency of coronary aneurysms compared with use of aspirin alone, as well as a reduction in morbidity and mortality when gamma-globulins are promptly administered. The recommended doses of intravenous gamma-globulin have been up to 2 g/kg, infused over 12-18 hours.[23]

In contrast, when aneurysm is left untreated or treated with aspirin alone, about one half of patients progress to aneurysmal dilatation within a few days, and they have increased risk for hemopericardium and death resulting from rupture. Patients with moderate-sized (> 3 mm) or larger aneurysms require further follow-up because they are at the highest risk for persistence of the aneurysms and future ischemic disease.[3,20,26] Within this group, most deaths occur within the first year of diagnosis, as a result of acute MI within the left coronary distribution; they have a 22% mortality rate with the first MI and up to an 83% mortality with the third MI.[26]

As many as 37% of patients may have silent MIs and, when symptomatic, children may not present with chest pain, instead presenting with inconsolable crying, abdominal pain, pallor, and vomiting. Because infants present most often with incomplete KD (resulting in delayed diagnosis), a low threshold for the initiation of therapy in this group is often necessary in the context of unexplained fever with no other clinical findings, in order to minimize the risk for coronary aneurysms.[27,28]

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