The percentage of Americans with heart disease, the No. 1 killer in the U.S., is continuing to fall, according to new research from the  Centers for Disease Control and Prevention.

The new statistics are published in the Oct. 14 issue of Morbidity and Mortality Weekly Report, a CDC publication.

In their study, CDC researchers looked through national Behavioral Risk Factor Surveillance System surveys for 2006 through 2010.

Six percent of adults had heart disease in 2010, which is down from 6.7 percent in 2006. Better treatments for high blood pressure and high cholesterol, along with a decrease in smoking, could explain this trend, as per experts.

The greatest declines in heart disease over the period were among whites: from 6.4 percent in 2006 to 5.8 percent in 2010. Hispanic Americans also had a significant drop in heart disease -- from 6.9 percent to 6.1 percent over the same time span. On the other hand, the rate of heart disease rose slightly among blacks, from 6.4 percent to 6.5 percent. American Indians/Alaska Natives had the highest prevalence of heart disease, at 11.6 percent, the CDC said.

The heart disease rate in 2010 was greatest among people 65 and older (19.8 percent), followed by people 45 to 64 (7.1 percent), and 1.2 percent for those between the ages of 18 and 44.

Thomas R. Frieden, director of the CDC, said despite the decline, heart disease is still the leading cause of death in the U.S., killing about the same number of Americans each year as cancer, lower respiratory diseases and accidents combined.

The states with the highest rates of heart disease in 2010 were Kentucky, with 8.2 percent reporting a diagnosis; West Virginia, with 8 percent and Louisiana, with 7.8 percent. The places with the lowest incidence were Hawaii with 3.7 percent and Washington, D.C., with 3.8 percent.