The Pediatric Cardiomyopathy Registry, which is funded by the National Heart, Lung and Blood Institute of the NIH, was set up to study the causes and natural history of the disease. A team of researchers from more than a dozen medical centers in the U.S. and Canada looked specifically at children in the registry who had cardiomyopathy caused by myocarditis, an inflammation of the heart. They looked at how those children were diagnosed and how their disease progressed over time.
“What we found is that children who had cardiomyopathy caused by myocarditis did much better than children who had dilated cardiomyopathy from an unknown cause,” said Steven E. Lipshultz, M.D., professor and chair of pediatrics at the University of Miami Miller School of Medicine, principal investigator and senior author of the study. “Of those same children with myocarditis, those who had early remodeling of their left ventricle and with more heart wall thinning, did worse over time than if remodeling had not taken place.”
Another important finding from the study was that it didn’t matter how the problem was diagnosed in terms of clinical outcome. In older children and teenagers, if someone is suspected of having myocarditis a biopsy is conducted by removing a piece of the heart muscle at some centers with expertise in this procedure. In younger children this can often be a risky procedure because a child must be sedated and their heart wall is much thinner, so making punctures to remove a sample is not without risk.
“Many people have thought a biopsy is essential to diagnose myocarditis in children, but our findings show that children diagnosed with myocarditis through a biopsy had the same future course as children who did not have heart muscle biopsies done, but whose pediatric cardiologists thought clinically they had myocarditis,” said James Wilkinson, M.D., professor of pediatrics and one of the study’s authors. “Something else we found is that the children with myocarditis who presented with the most evidence of cardiac abnormalities, tended to be the same children who got better during the period of follow-up we used.”
Dilated cardiomyopathy affects 1 in 100,000 children, and nearly 40 percent with symptomatic disease receive a heart transplant or fail medical management and die within two years of diagnosis. The Pediatric Cardiomyopathy Registry has information on more than 4,000 children from 1990 through 2010.