Signs of cardiac disease start early in obese children

ORLANDO, Fla. — Obese children as young as 8 years old may experience worrisome changes to their hearts, according to data presented November 10 at the American Heart Association’s annual scientific sessions.

While the study was small, involving 20 obese children, it found that 40 percent of the kids had enlarged hearts, a sign that the organ is under strain. The study is one of the few to use MRI to get a close look at cardiac muscle, said Linyuan Jing of Geisinger Health System in Danville, Pa. Her team’s data add to a disturbing number of studies suggesting that children who are overweight or obese could be setting themselves up for lifelong cardiac problems (SN Online: 5/21/12).          

The prevalence of childhood obesity in the United States has leveled off in recent years, but remains high. More than a third of children are considered overweight or obese — a number that has doubled among children and quadrupled for adolescents in the last 30 years, according to the U.S. Centers for Disease Control and Prevention.

The consequences are playing out in children’s health. In the 1980s, type 2 diabetes — a disease associated with obesity — was virtually unheard of in teenagers; today, it comprises 15 percent of diabetes diagnoses among adolescents.     

Other studies are finding evidence that youth does not protect the heart from obesity-related problems. The Bogalusa Heart Study, one of the few tracking children into adulthood, found that some overweight preschool children showed elevated cholesterol levels. After following children in the study for an average of 28 years, researchers reported last year in the Journal of the American College of Cardiology that children with a high body mass index and high blood pressure were more likely to have left ventricular hypertrophy (an unhealthy thickening of heart muscle) as adults.

Newer data have raised concerns that this kind of heart enlargement may begin in childhood. But it’s been hard to get clear images of the heart in obese children, Jing said. For instance, echocardiograms, which use ultrasound waves to produce an image, are easier to obtain in normal-weight children with less body fat.

In the new study, sponsored by the National Institutes of Health, Jing and her colleagues evaluated the cardiac MRIs of 20 obese children ages 8 to 18 and compared them with 20 healthy weight peers. The doctors assessed the state of the left ventricle, the heart’s largest and most muscular pumping chamber. They found that the obese children were more likely to have enlarged hearts. Their left ventricular mass was 27 percent higher on average than that of healthy-weight children, and their heart muscle was 12 percent thicker, even after taking into account the children’s ages.

“This adds to the data trail saying childhood obesity can have consequences right during childhood,” said Sarah deFerranti, director of the preventive cardiology program at Boston Children’s Hospital. “The nice thing about this study was the way the data were obtained.”

The long-term consequences of the heart changes aren’t known. In adults, an enlarged heart is associated with premature death. In children, the significance is still under study. “We don’t know if it’s reversible,” Jing said. “We certainly hope so.”