The existence of certain risk factors at the time children are diagnosed with hypertrophic cardiomyopathy may signal a worse prognosis, according to a study published online Sept. 3 in The Lancet. Researchers found that diagnosis at younger than one year of age, inborn errors of metabolism, mixed types of hypertrophic cardiomyopathy, low body weight, congestive heart failure or abnormal structure or function of the left ventricle as indicated by echocardiography were associated with a higher risk of death or heart transplantation.

The study authors analyzed nationwide registry data from infants and children diagnosed with cardiomyopathy between 1990 and 2009 at pediatric cardiology centers in the U.S. and Canada.

“Our goal was to understand how patient factors measured at diagnosis predicted the subsequent risk of the primary outcome of death or heart transplantation,” wrote the authors, led by Steven E. Lipshultz, MD, of the University of Miami Miller School of Medicine.

The 1,085 children were broken down by type of hypertrophic cardiomyopathy—pure, mixed hypertrophic and dilated, and mixed hypertrophic with restrictive (or other). The pure cases were separated based on age at diagnosis and presumed cause into six subgroups—idiopathic hypertrophic cardiomyopathy diagnosed at younger than one year old, idiopathic hypertrophic cardiomyopathy diagnosed at one year and older, hypertrophic cardiomyopathy with malformation syndromes, hypertrophic cardiomyopathy with inborn errors of metabolism, hypertrophic cardiomyopathy with neuromuscular disease and familial hypertrophic cardiomyopathy.

The 69 children with pure hypertrophic cardiomyopathy with inborn errors of metabolism had the poorest outcomes—the estimated death or heart transplantation rate was 57 percent at two years. The prognosis was also poor for children with mixed types of cardiomyopathy as well as for children who were younger, low weight, had congestive heart failure and certain ventricular abnormalities.

In all the subgroups of hypertrophic cardiomyopathy, the risk of death or transplantation was higher if there were two or more risk factors and if the number of risk factors increased.

Although cardiomyopathy is rare in infants and children, identifying risk factors could help shape treatment plans in ways that maximize the potential for better outcomes.

“The presence of multiple risk factors at diagnosis predicts the worst clinical outcomes; those children should be evaluated for early heart transplantation or heightened clinical monitoring,” the authors wrote.