May 3 (HealthDay News) -- While untreated hypertension in any child could lead them to developing a potentially dangerous enlargement or thickening of one chamber of the heart, a new study suggests that black children may be at a greater risk than all other racial groups.

While studying 139 high blood pressure patients under age 21, researchers from Johns Hopkins Children's Center found that about 60 percent of those who were black had left ventricular hypertrophy (LVH), a condition that can cause heart failure, problems with heart rhythm and death. The researchers found LVH in just 37 percent of the other children.

And unlike the others in the study, the black children with LVH were also found to have higher cholesterol levels -- another risk factor for cardiovascular disease.

"Our study identifies black children with hypertension as a special group who may be at particularly high risk for heart disease as they age because of several risk factors, and pediatricians treating these kids should follow them very closely," study author Dr. Cozumel Pruette, a kidney specialist at the children's center, said in a Hopkins news release.

The study is scheduled to be presented this weekend in Baltimore at the annual meeting of the Pediatric Academic Societies.

Chronic high blood pressure, or hypertension, in U.S. children has been steadily on the rise in recent decades, affecting an estimated 4 million children, the researchers said.

SOURCE: Johns Hopkins Children's Center, news release, May 2, 2009