Elevated heart rate in children with one type of heart failure increases risk of dying or needing a heart transplant

BUFFALO, N.Y. — Children with dilated cardiomyopathy, a common cause of heart failure in children, who have an elevated heart rate are at a higher risk of death than children with the condition who do not have an elevated heart rate, a new paper published last week in the Journal of the American Heart Association has found.

Dilated cardiomyopathy is the most common type of cardiomyopathy in children. It prevents the heart from pumping blood effectively because the main pumping chamber of the heart is too stretched out. According to data published in 2003 by the Pediatric Cardiomyopathy Registry (PCMR) in the New England Journal of Medicine, the estimated incidence of pediatric cardiomyopathy is 1.1.3 cases per 100,000 children. Most cases are identified at an early age, and the incidence varies according to sex, region, and racial or ethnic origin.

Funded by Amgen Inc., the research was conducted at multiple sites in the U.S. and Canada participating in the PCMR, which was founded more than 25 years ago by Steven Lipshultz, MD, chair of the Department of Pediatrics in the Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo and principal investigator on the Amgen research.

The registry was developed to collect and organize relevant data on the condition, with the goal of increasing awareness of the condition and its causes, as well as to spur new diagnostic and therapeutic interventions. Lipshultz is director of the registry.

“Until recently, there was no improvement in medical management for children with dilated cardiomyopathy and heart failure and, as a result, this has been the leading cause of heart transplantation in children 2-18 years of age around the world,” said Lipshultz, who co-authored the paper. The first author is Joseph W. Rossano, MD, co-director of the Cardiac Center and chief of the Division of Cardiology at Children’s Hospital of Philadelphia.

‘Some of the worst outcomes’

“More than half of these children have died or needed heart transplant within the first two years after presentation,” Lipshultz continued. “This represents some of the worst outcomes seen by pediatric cardiologists.”

A total of 557 patients, recruited from the PCMR, were included in the study. According to the findings, of the 192 children with an elevated heart rate, 38 (19.8%) died without heart transplant (which may have saved them); among the 365 children with a normal heart rate, 39 (10.7%) died without heart transplant.

In children in the study who had an elevated heart rate, the median heart rate was 149 as compared to a median heart rate of 119 among the children with a normal heart rate.

The findings are especially significant, Lipshultz said, because most established risk factors for poor outcomes in children with dilated cardiomyopathy, such as patient age, cause of cardiomyopathy and the size and function of the left ventricle, ­cannot be modified by clinical intervention.

An important ‘biomarker’

“Heart rate hasn’t previously been seen as a risk factor for poor outcomes in children with dilated cardiomyopathy,” Lipshultz explained. “This research suggests that heart rate may, in fact, serve as an important ‘biomarker’ in this population, and that reducing heart rate could turn out to be a key therapeutic target for these children.”

These observational findings provide the impetus for more study to assess the utility of therapies that control elevated heart rate and how they might improve the survival of these children, he added.

“This research shows that the child’s resting heart rate is one of the strongest predictors of future survival or avoiding a heart transplant in these patients with dilated cardiomyopathy and heart failure who present to cardiologists in the PCMR,” said Lipshultz.  

He noted that for children with higher resting heart rates, even when controlling for other factors that could confound this result, a higher resting heart rate portents a significantly worse clinical outcome, with much higher rates of failing medical management and needing a heart transplant or dying.

“These new findings are important for the identification of high-risk patients who might benefit from early listing for a heart transplant since donor availability is often limited, and also for family counseling and planning,” Lipshultz explained.

He added that some of the newest potentially effective therapies for treating heart failure in children target heart rate and their effect is to lower heart rate in these patients. 

“New studies are already underway, investigating this testable hypothesis for children with heart failure and dilated cardiomyopathy to see if lowering heart rate with these new classes of therapy that have never been used in these children before improve their outcomes,” said Lipshultz.

The Pediatric Cardiomyopathy Registry is funded by the National Heart, Lung and Blood Institute and the Children’s Cardiomyopathy Foundation.

Other co-authors of this study include Paul F. Kantor, MBBCh, and Robert E. Shaddy, MD, from the Children’s Hospital Los Angeles; Ling Shi, PhD, from the New England Research Institutes; James D. Wilkinson, MD, MPH, from Vanderbilt University; John L. Jefferies, MD, from the University of Tennessee; Jason D. Czechor, MS, and Hiedy Razoky, MBA, from Wayne State University; and Heidi Wirtz, PharmD, PhD, and Christophe Depre, MD, PhD, from Amgen Inc.