VAIL, COLO. – The majority of coronary artery abnormalities occurring in a large series of children with Kawasaki disease were detected at the time of hospital admission, prior to treatment.
What this means is that, contrary to the conventional wisdom, there is no such thing as a safe window for diagnosis and treatment of Kawasaki disease, Dr. Samuel R. Dominguez stressed at a conference on pediatric infectious diseases sponsored by the Children’s Hospital Colorado.
Dr. Samuel R. Dominguez
The "safe window" concept dates back to a classic 26-year-old study that concluded that treating patients with Kawasaki disease by day 10 of their illness greatly reduced the incidence of coronary artery aneurysms, the most serious disease complication (N. Engl. J. Med. 1986;315:341-7).
Anecdotal experience to the contrary convinced Dr. Dominguez and coworkers at Children’s Hospital Colorado in Aurora that it was time to take a formal look at their institutional experience.
"It was our gestalt that some kids had coronary artery abnormalities much earlier in the course of their illness than what we’d thought from the literature. We had this growing sense that the development of coronary artery lesions was less common after discharge than we’d initially thought," the pediatric infectious disease specialist explained.
That proved to be the case.
Among all 210 patients who were admitted for Kawasaki disease over a 4-year period (all of whom were appropriately treated with intravenous immunoglobulin and aspirin), 27% had coronary artery abnormalities detected during their acute illness or subsequent outpatient follow-up. In 81% of affected kids, the coronary artery abnormalities were identified on the basis of a z score of 2.5 or above on the initial echocardiogram that was obtained at the time of admission. The coronary lesions were identified in 21% of affected children on or before day 5 of their illness, in 60% on or before day 7, and in 80% on or before day 10 of their illness.
The Colorado findings are supported by other fairly recent studies, according to Dr. Dominguez. An analysis of the Pediatric Health Information System database that included nearly 5,200 admissions for Kawasaki disease at 27 U.S. pediatric hospitals during 2001-2006 found that 3.3% of patients developed coronary artery aneurysms, 81% of which were detected during their initial hospitalization (Pediatrics 2009;124:1-8). And a Pediatric Heart Network study concluded that Kawasaki disease patients with a normal echocardiogram on admission had only a 6% incidence of developing coronary lesions at a later time, meaning that most coronary abnormalities were present at admission (Circulation 2007;116:174-9).
Intriguingly, fully 46% of Kawasaki disease patients in the Colorado study who had coronary lesions on admission had incomplete Kawasaki disease.
"That’s a much higher rate than we think of," Dr. Dominguez said. "It raises the concern that many cases of Kawasaki disease may currently be undiagnosed and not treated."
Incomplete Kawasaki disease is a diagnostic category that was created in the revised American Heart Association guidelines in an effort to identify subsets of Kawasaki disease patients earlier so treatment can be started expeditiously (Circulation 2004;110:2747-71). The revision was made in response to recognition that infants often fail to meet the classic diagnostic criteria for Kawasaki disease, yet they have a high incidence of coronary artery aneurysms.
The revised guidelines basically state that infants aged 6 months or younger on day 7 of fever without other explanation should undergo laboratory testing, even if they don’t have a generalized rash, bilateral nonexudative conjunctivitis, or any of the other clinical criteria for classic Kawasaki disease. If lab results yield evidence of systemic inflammation, then echocardiography is warranted (Pediatrics 2004;114:1708-33).
Dr. Dominguez said the clear implication of the Colorado study is that earlier diagnosis and treatment are needed in order to reduce the incidence of coronary artery abnormalities in children with Kawasaki disease. Increased clinical suspicion, greater use of the published algorithm for incomplete Kawasaki disease, and earlier resort to echocardiography in the initial work-up may result in more rapid therapy.
Although there is no guarantee that earlier diagnosis and treatment will prevent coronary lesions, that is the hope, he added.
The Children’s Hospital Colorado study was recently published (Pediatr. Infect. Dis. J. 2012 July 3 [doi:10.1097/INF.0b013e318266bcf9]).
Dr. Dominguez reported having no financial conflicts.