| Complication | Frequency | Comments |
| Shock | Approximately 7% | - Associated features:
- Consumptive coagulopathy and cardiac abnormalities including impaired left ventricular systolic function, mitral regurgitation, and CAAs
- Higher C-reactive protein levels
- Less responsive to initial IVIG therapy and more commonly requires additional treatment
|
| Macrophage activation syndrome | Rare | - Reported rarely in children with persistent fever after IVIG treatment
- Heralded by fall in ESR due to consumptive coagulopathy; also marked by ferritin levels >5000 ng/mL
- Treatment with intravenous methylprednisolone, biologic response modifiers, or cyclosporine may be needed
|
| Cardiac complications |
| CAAs (including dilation and/or aneurysm) | CAAs occur in approximately one-quarter of patients with KD in the IVIG era Coronary artery aneurysms develop in approximately 4% of patients treated with IVIG | - Risk factors associated with CAAs include:
- Late diagnosis and delayed treatment with IVIG
- Age <1 year or >9 years
- Male sex
- Fever ≥14 days
- Serum sodium <135 mEq/L, hematocrit <35%, white cell count >12,000/mm3
|
| Ventricular dysfunction | Occurs during the acute phase in one-quarter to one-half of patients with KD | - In most cases, ventricular function is in only mildly or moderately depressed; severe ventricular dysfunction is rare
- Most commonly manifested by tachycardia and an S3 gallop; uncommonly may progress to heart failure
- May be caused by direct myocardial inflammation (ie, myocarditis) or from indirect negative inotropic effects of the systemic inflammatory response; ischemic cardiomyopathy may occur in patients after myocardial infarction
- Ventricular function usually improves rapidly after treatment with IVIG
|
| Valvular regurgitation | Mitral regurgitation is common in the acute phase Aortic root dilation is common; aortic regurgitation is less common | - Mitral regurgitation usually resolves in the convalescent phase
- Aortic root dilation may persist during the first year of follow-up
|
| Pericardial effusion | Occurs in <5% of patients | - Very rarely causes tamponade
|
| Myocardial infarction | Rare | - Principal cause of mortality in KD
- Occurs only in patients with CAAs, most frequently in patients with giant CAAs
- Highest risk period is in the first 6 to 12 months, but risk continues into adulthood
|
| Arrhythmia | Rare | - Rarely occurs during the acute phase as a consequence of acute myocarditis
- Beyond the acute/subacute phase of illness, arrhythmia occurs chiefly as a consequence of myocardial ischemia or infarction
- Ventricular arrhythmias are likely indicators of underlying myocardial damage and are associated with increased risk of sudden death
|
| Accelerated atherosclerosis | Rare in patients without CAAs | - Patients who have CAAs in the acute phase that persist in follow-up are considered to be at high risk for early atherosclerotic disease
- Patients who have CAAs in the acute phase that regress to normal during follow-up are considered to be at moderate risk for early atherosclerotic disease
- Patients who never had CAAs do not appear to be at increased risk for cardiovascular disease compared with the general pediatric population
|
| Noncoronary vascular involvement | Peripheral (rare) Visceral (very rare) | - Peripheral aneurysms may present as pulsatile masses in axillae or inguinal area
- Peripheral arterial obstruction can lead to ischemia and gangrene
- Most commonly occurs in children with severe KD, including those with large or giant CAAs
|
| Urinary abnormalities and renal disease | Rare | - Includes acute interstitial nephritis, mild proteinuria, acute kidney injury, hemolytic-uremic syndrome, and immune complex-mediated glomerulonephritis
- IVIG may also cause acute kidney injury, especially preparations using sucrose as a stabilizer
|
| GI abnormalities | Mild GI manifestations occur commonly; severe involvement is rare | - Mild GI involvement includes gallbladder hydrops, cholestasis, and paralytic ileus
- More severe involvement includes bile duct stenosis, appendicular vasculitis, hemorrhagic duodenitis, intestinal pseudo-obstruction, intussusception, and pancreatitis
|
| Sensorineural hearing loss | Rare | - Usually transient
- Persistent sensorineural hearing loss is associated with delayed use of IVIG, prolonged thrombocytosis, anemia, and an elevated ESR
|
